Literature using and/or citing CarbonTracker
Please email us if you have suggested additions to this list.| Aalto T, Hatakka J, Kouznetsov R and Stanislawska K (2015), "Background and anthropogenic influences on atmospheric CO2 concentrations measured at Pallas: comparison of two models for tracing air mass history", BOREAL ENVIRONMENT RESEARCH., APR 30, 2015. Vol. {20}({2}), pp. 213-226. |
| Abstract: The FLEXTRA and SILAM models were utilized in estimating the influence regions (TR) for the measured CO2 concentration ([CO2]) at Pallas together with tracers for anthropogenic emissions. The models produced similar synoptic features and associated background [CO2] with marine IR and elevated [CO2] with continental IR, but there were also differences which affected the interpretation of measurements. The background, i.e. marine boundary layer (MBL) signal, was compared to the NOAA MBL reference. Both models performed well, with monthly mean deviations from the reference usually inside 1 ppm. The FLEXTRA MBL signal had some seasonality in the difference, however, only very few cases were associated with anthropogenic emissions. We used [CO] and fossil fuel [CO2] simulations by the TM5 (CarbonTracker CT2011oi) model as emission tracers. The model and [CO] captured well the timing of high [CO2] in measurements. The anthropogenic influence was more pronounced in winter than in summer, and it had a large inter-annual variation. |
BibTeX:
@article{aalto15a,
author = {Aalto, Tuula and Hatakka, Juha and Kouznetsov, Rostislav and Stanislawska, Karolina},
title = {Background and anthropogenic influences on atmospheric CO2 concentrations measured at Pallas: comparison of two models for tracing air mass history},
journal = {BOREAL ENVIRONMENT RESEARCH},
year = {2015},
volume = {20},
number = {2},
pages = {213--226}
}
|
| Agol E, Jansen T, Lacy B, Robinson TD and Meadows V ({2015}), "THE CENTER OF LIGHT: SPECTROASTROMETRIC DETECTION OF EXOMOONS", ASTROPHYSICAL JOURNAL., OCT 10, {2015}. Vol. {812}({1}) |
| Abstract: Direct imaging of extrasolar planets with future space-based coronagraphic telescopes may provide a means of detecting companion moons at wavelengths where the moon outshines the planet. We propose a detection strategy based on the positional variation of the center of light with wavelength, ``spectroastrometry.'' This new application of this technique could be used to detect an exomoon, to determine the exomoon's orbit and the mass of the host exoplanet, and to disentangle the spectra of the planet and moon. We consider two model systems, for which we discuss the requirements for detection of exomoons around nearby stars. We simulate the characterization of an Earth-Moon analog system with spectroastrometry, showing that the orbit, the planet mass, and the spectra of both bodies can be recovered. To enable the detection and characterization of exomoons we recommend that coronagraphic telescopes should extend in wavelength coverage to 3 mu m, and should be designed with spectroastrometric requirements in mind. |
BibTeX:
@article{agol15a,
author = {Agol, Eric and Jansen, Tiffany and Lacy, Brianna and Robinson, Tyler D. and Meadows, Victoria},
title = {THE CENTER OF LIGHT: SPECTROASTROMETRIC DETECTION OF EXOMOONS},
journal = {ASTROPHYSICAL JOURNAL},
year = {2015},
volume = {812},
number = {1},
doi = {10.1088/0004-637X/812/1/5}
}
|
| Agusti-Panareda A, Massart S, Chevallier F, Balsamo G, Boussetta S, Dutra E and Beljaars A ({2016}), "A biogenic CO2 flux adjustment scheme for the mitigation of large-scale biases in global atmospheric CO2 analyses and forecasts", ATMOSPHERIC CHEMISTRY AND PHYSICS., AUG 18, {2016}. Vol. {16}({16}), pp. 10399-10418. |
| Abstract: Forecasting atmospheric CO2 daily at the global scale with a good accuracy like it is done for the weather is a challenging task. However, it is also one of the key areas of development to bridge the gaps between weather, air quality and climate models. The challenge stems from the fact that atmospheric CO2 is largely controlled by the CO2 fluxes at the surface, which are difficult to constrain with observations. In particular, the biogenic fluxes simulated by land surface models show skill in detecting synoptic and regional-scale disturbances up to sub-seasonal time-scales, but they are subject to large seasonal and annual budget errors at global scale, usually requiring a posteriori adjustment. This paper presents a scheme to diagnose and mitigate model errors associated with biogenic fluxes within an atmospheric CO2 forecasting system. The scheme is an adaptive scaling procedure referred to as a biogenic flux adjustment scheme (BFAS), and it can be applied automatically in real time throughout the forecast. The BFAS method generally improves the continental budget of CO2 fluxes in the model by combining information from three sources: (1) retrospective fluxes estimated by a global flux inversion system, (2) land-use information, (3) simulated fluxes from the model. The method is shown to produce enhanced skill in the daily CO2 10-day forecasts without requiring continuous manual intervention. Therefore, it is particularly suitable for near-real-time CO2 analysis and forecasting systems. |
BibTeX:
@article{agusti-panareda16a,
author = {Agusti-Panareda, Anna and Massart, Sebastien and Chevallier, Frederic and Balsamo, Gianpaolo and Boussetta, Souhail and Dutra, Emanuel and Beljaars, Anton},
title = {A biogenic CO2 flux adjustment scheme for the mitigation of large-scale biases in global atmospheric CO2 analyses and forecasts},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2016},
volume = {16},
number = {16},
pages = {10399--10418},
doi = {10.5194/acp-16-10399-2016}
}
|
| Ahlstrom A, Miller PA and Smith B ({2012}), "Too early to infer a global NPP decline since 2000", GEOPHYSICAL RESEARCH LETTERS., AUG 10, {2012}. Vol. {39} |
| Abstract: The global terrestrial carbon cycle plays a pivotal role in regulating the atmospheric composition of greenhouse gases. It has recently been suggested that the upward trend in net primary production (NPP) seen during the 1980's and 90's has been replaced by a negative trend since 2000 induced by severe droughts mainly on the southern hemisphere. Here we compare results from an individual-based global vegetation model to satellite-based estimates of NPP and top-down reconstructions of net biome production (NBP) based on inverse modelling of observed CO2 concentrations and CO2 growth rates. We find that simulated NBP exhibits considerable covariation on a global scale with interannual fluctuations in atmospheric CO2. Our simulations also suggest that droughts in the southern hemisphere may have been a major driver of NPP variations during the past decade. The results, however, do not support conjecture that global terrestrial NPP has entered a period of drought-induced decline. Citation: Ahlstrom, A., P. A. Miller, and B. Smith (2012), Too early to infer a global NPP decline since 2000, Geophys. Res. Lett., 39, L15403, doi:10.1029/2012GL052336. |
BibTeX:
@article{ahlstrom12a,
author = {Ahlstrom, Anders and Miller, Paul A. and Smith, Benjamin},
title = {Too early to infer a global NPP decline since 2000},
journal = {GEOPHYSICAL RESEARCH LETTERS},
year = {2012},
volume = {39},
doi = {10.1029/2012GL052336}
}
|
| Ahue WK (2010), "Regional carbon fluxes and boundary layer heights from the Airborne Carbon in the Mountains Experiment 2007". Thesis at: University of Wisconsin--Madison.
[BibTeX] |
BibTeX:
@phdthesis{ahue10a,
author = {Ahue, William KM},
title = {Regional carbon fluxes and boundary layer heights from the Airborne Carbon in the Mountains Experiment 2007},
school = {University of Wisconsin--Madison},
year = {2010}
}
|
| Alden CB, Miller JB and White JWC ({2010}), "Can bottom-up ocean CO2 fluxes be reconciled with atmospheric 13C observations?", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 369-388. |
| Abstract: The rare stable carbon isotope, 13C, has been used previously to partition CO2 fluxes into land and ocean components. Net ocean and land fluxes impose distinctive and predictable fractionation patterns upon the stable isotope ratio, making it an excellent tool for distinguishing between them. Historically, isotope constrained inverse methods for calculating CO2 surface fluxes-the `double deconvolution'-have disagreed with bottom-up ocean flux estimates. In this study, we use the double deconvolution framework, but add, as a constraint, independent estimates of time histories of ocean fluxes to the atmospheric observations of CO2 and 13CO(2). We calculate timeseries of net land flux, total disequilibrium flux and terrestrial disequilibrium flux from 1991 to 2008 that are consistent with bottom-up net ocean fluxes. We investigate possible drivers of interannual variability in terrestrial disequilibrium flux, including terrestrial discrimination, and test the sensitivity of our results to those mechanisms. We find that C-3 plant discrimination and shifts in the global composition of C-3 and C-4 vegetation are likely drivers of interannual variability in terrestrial disequilibrium flux, while contributions from heterotrophic respiration and disturbance anomalies are also possible. |
BibTeX:
@article{alden10a,
author = {Alden, Caroline B. and Miller, John B. and White, James W. C.},
title = {Can bottom-up ocean CO2 fluxes be reconciled with atmospheric 13C observations?},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2010},
volume = {62},
number = {5, SI},
pages = {369--388},
doi = {10.1111/j.1600-0889.2010.00481.x}
}
|
| Alden CB, Miller JB, Gatti LV, Gloor MM, Guan K, Michalak AM, van der Laan-Luijkx IT, Touma D, Andrews A, Basso LS, Correia CSC, Domingues LG, Joiner J, Krol MC, Lyapustin AI, Peters W, Shiga YP, Thoning K, van der Velde IR, van Leeuwen TT, Yadav V and Diffenbaugh NS ({2016}), "Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange", GLOBAL CHANGE BIOLOGY., OCT, {2016}. Vol. {22}({10}), pp. 3427-3443. |
| Abstract: Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate-carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO2 with the atmosphere ( NBE), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub-Basin Amazon NBE estimates have relied heavily on process-based biosphere models, despite lack of model agreement with plot-scale observations. We present a new analysis of airborne measurements that reveals monthly, regional-scale (similar to 1-8 x 10(6) km(2)) NBE variations. We develop a regional atmospheric CO2 inversion that provides the first analysis of geographic and temporal variability in Amazon biosphere-atmosphere carbon exchange and that is minimally influenced by biosphere model-based first guesses of seasonal and annual mean fluxes. We find little evidence for a clear seasonal cycle in Amazon NBE but do find NBE sensitivity to aberrations from long-term mean climate. In particular, we observe increased NBE ( more carbon emitted to the atmosphere) associated with heat and drought in 2010, and correlations between wet season NBE and precipitation ( negative correlation) and temperature ( positive correlation). In the eastern Amazon, pulses of increased NBE persisted through 2011, suggesting legacy effects of 2010 heat and drought. We also identify regional differences in postdrought NBE that appear related to long-term water availability. We examine satellite proxies and find evidence for higher gross primary productivity ( GPP) during a pulse of increased carbon uptake in 2011, and lower GPP during a period of increased NBE in the 2010 dry season drought, but links between GPP and NBE changes are not conclusive. These results provide novel evidence of NBE sensitivity to short-term temperature and moisture extremes in the Amazon, where monthly and sub-Basin estimates have not been previously available. |
BibTeX:
@article{alden16a,
author = {Alden, Caroline B. and Miller, John B. and Gatti, Luciana V. and Gloor, Manuel M. and Guan, Kaiyu and Michalak, Anna M. and van der Laan-Luijkx, Ingrid T. and Touma, Danielle and Andrews, Arlyn and Basso, Luana S. and Correia, Caio S. C. and Domingues, Lucas G. and Joiner, Joanna and Krol, Maarten C. and Lyapustin, Alexei I. and Peters, Wouter and Shiga, Yoichi P. and Thoning, Kirk and van der Velde, Ivar R. and van Leeuwen, Thijs T. and Yadav, Vineet and Diffenbaugh, Noah S.},
title = {Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange},
journal = {GLOBAL CHANGE BIOLOGY},
year = {2016},
volume = {22},
number = {10},
pages = {3427--3443},
doi = {10.1111/gcb.13305}
}
|
| Alexandrov GA and Matsunaga T (2008), "Normative productivity of the global vegetation", Carbon balance and management. Vol. 3(1), pp. 8. Springer.
[BibTeX] |
BibTeX:
@article{alexandrov08a,
author = {Alexandrov, Georgii A and Matsunaga, Tsuneo},
title = {Normative productivity of the global vegetation},
journal = {Carbon balance and management},
publisher = {Springer},
year = {2008},
volume = {3},
number = {1},
pages = {8}
}
|
| Alexe M, Bergamaschi P, Segers A, Detmers R, Butz A, Hasekamp O, Guerlet S, Parker R, Boesch H, Frankenberg C, Scheepmaker RA, Dlugokencky E, Sweeney C, Wofsy SC and Kort EA ({2015}), "Inverse modelling of CH4 emissions for 2010-2011 using different satellite retrieval products from GOSAT and SCIAMACHY", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({1}), pp. 113-133. |
| Abstract: At the beginning of 2009 new space-borne observations of dry-air column-averaged mole fractions of atmospheric methane (XCH4) became available from the Thermal And Near infrared Sensor for carbon Observations-Fourier Transform Spectrometer (TANSO-FTS) instrument on board the Greenhouse Gases Observing SATellite (GOSAT). Until April 2012 concurrent methane (CH4) retrievals were provided by the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) instrument on board the ENVironmental SATellite (ENVISAT). The GOSAT and SCIAMACHY XCH4 retrievals can be compared during the period of overlap. We estimate monthly average CH4 emissions between January 2010 and December 2011, using the TM5-4DVAR inverse modelling system. In addition to satellite data, high-accuracy measurements from the Cooperative Air Sampling Network of the National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA ESRL) are used, providing strong constraints on the remote surface atmosphere. We discuss five inversion scenarios that make use of different GOSAT and SCIAMACHY XCH4 retrieval products, including two sets of GOSAT proxy retrievals processed independently by the Netherlands Institute for Space Research (SRON)/Karlsruhe Institute of Technology (KIT), and the University of Leicester (UL), and the RemoTeC ``Full-Physics'' (FP) XCH4 retrievals available from SRON/KIT. The GOSAT-based inversions show significant reductions in the root mean square (rms) difference between retrieved and modelled XCH4, and require much smaller bias corrections compared to the inversion using SCIAMACHY retrievals, reflecting the higher precision and relative accuracy of the GOSAT XCH4. Despite the large differences between the GOSAT and SCIAMACHY retrievals, 2-year average emission maps show overall good agreement among all satellite-based inversions, with consistent flux adjustment patterns, particularly across equatorial Africa and North America. Over North America, the satellite inversions result in a significant redistribution of CH4 emissions from North-East to South-Central United States. This result is consistent with recent independent studies suggesting a systematic underestimation of CH4 emissions from North American fossil fuel sources in bottom-up inventories, likely related to natural gas production facilities. Furthermore, all four satellite inversions yield lower CH4 fluxes across the Congo basin compared to the NOAA-only scenario, but higher emissions across tropical East Africa. The GOSAT and SCIAMACHY inversions show similar performance when validated against independent shipboard and aircraft observations, and XCH4 retrievals available from the Total Carbon Column Observing Network (TCCON). |
BibTeX:
@article{alexe15a,
author = {Alexe, M. and Bergamaschi, P. and Segers, A. and Detmers, R. and Butz, A. and Hasekamp, O. and Guerlet, S. and Parker, R. and Boesch, H. and Frankenberg, C. and Scheepmaker, R. A. and Dlugokencky, E. and Sweeney, C. and Wofsy, S. C. and Kort, E. A.},
title = {Inverse modelling of CH4 emissions for 2010-2011 using different satellite retrieval products from GOSAT and SCIAMACHY},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2015},
volume = {15},
number = {1},
pages = {113--133},
doi = {10.5194/acp-15-113-2015}
}
|
| Allen M, Erickson D, Kendall W, Fu J, Ott L and Pawson S ({2012}), "The influence of internal model variability in GEOS-5 on interhemispheric CO2 exchange", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 19, {2012}. Vol. {117} |
| Abstract: An ensemble of eight atmospheric CO2 simulations was completed employing the National Aeronautics and Space Administration (NASA) Goddard Earth Observation System, Version 5 (GEOS-5) for the years 2000-2001, each with initial meteorological conditions corresponding to different days in January 2000 to examine internal model variability. Globally, the model runs show similar concentrations of CO2 for the two years, but in regions of high CO2 concentrations due to fossil fuel emissions, large differences among different model simulations appear. The phasing and amplitude of the CO2 cycle at Northern Hemisphere locations in all of the ensemble members is similar to that of surface observations. In several southern hemisphere locations, however, some of the GEOS-5 model CO2 cycles are out of phase by as much as four months, and large variations occur between the ensemble members. This result indicates that there is large sensitivity to transport in these regions. The differences vary by latitude-the most extreme differences in the Tropics and the least at the South Pole. Examples of these differences among the ensemble members with regard to CO2 uptake and respiration of the terrestrial biosphere and CO2 emissions due to fossil fuel emissions are shown at Cape Grim, Tasmania. Integration-based flow analysis of the atmospheric circulation in the model runs shows widely varying paths of flow into the Tasmania region among the models including sources from North America, South America, South Africa, South Asia and Indonesia. These results suggest that interhemispheric transport can be strongly influenced by internal model variability. |
BibTeX:
@article{allen12a,
author = {Allen, Melissa and Erickson, David and Kendall, Wesley and Fu, Joshua and Ott, Lesley and Pawson, Steven},
title = {The influence of internal model variability in GEOS-5 on interhemispheric CO2 exchange},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2012},
volume = {117},
doi = {10.1029/2011JD017059}
}
|
| Andres RJ, Boden TA, Breon FM, Ciais P, Davis S, Erickson D, Gregg JS, Jacobson A, Marland G, Miller J, Oda T, Olivier JGJ, Raupach MR, Rayner P and Treanton K ({2012}), "A synthesis of carbon dioxide emissions from fossil-fuel combustion", BIOGEOSCIENCES. Vol. {9}({5}), pp. 1845-1871. |
| Abstract: This synthesis discusses the emissions of carbon dioxide from fossil-fuel combustion and cement production. While much is known about these emissions, there is still much that is unknown about the details surrounding these emissions. This synthesis explores our knowledge of these emissions in terms of why there is concern about them; how they are calculated; the major global efforts on inventorying them; their global, regional, and national totals at different spatial and temporal scales; how they are distributed on global grids (i.e., maps); how they are transported in models; and the uncertainties associated with these different aspects of the emissions. The magnitude of emissions from the combustion of fossil fuels has been almost continuously increasing with time since fossil fuels were first used by humans. Despite events in some nations specifically designed to reduce emissions, or which have had emissions reduction as a byproduct of other events, global total emissions continue their general increase with time. Global total fossil-fuel carbon dioxide emissions are known to within 10br> uncertainty (95% confidence interval). Uncertainty on individ-ual national total fossil-fuel carbon dioxide emissions range from a few percent to more than 50 %. This manuscript concludes that carbon dioxide emissions from fossil-fuel combustion continue to increase with time and that while much is known about the overall characteristics of these emissions, much is still to be learned about the detailed characteristics of these emissions. |
BibTeX:
@article{andres12a,
author = {Andres, R. J. and Boden, T. A. and Breon, F. -M. and Ciais, P. and Davis, S. and Erickson, D. and Gregg, J. S. and Jacobson, A. and Marland, G. and Miller, J. and Oda, T. and Olivier, J. G. J. and Raupach, M. R. and Rayner, P. and Treanton, K.},
title = {A synthesis of carbon dioxide emissions from fossil-fuel combustion},
journal = {BIOGEOSCIENCES},
year = {2012},
volume = {9},
number = {5},
pages = {1845--1871},
doi = {10.5194/bg-9-1845-2012}
}
|
| Andrews AE, Kofler JD, Trudeau ME, Williams JC, Neff DH, Masarie KA, Chao DY, Kitzis DR, Novelli PC, Zhao CL, Dlugokencky EJ, Lang PM, Crotwell MJ, Fischer ML, Parker MJ, Lee JT, Baumann DD, Desai AR, Stanier CO, De Wekker SFJ, Wolfe DE, Munger JW and Tans PP ({2014}), "CO2, CO, and CH4 measurements from tall towers in the NOAA Earth System Research Laboratory's Global Greenhouse Gas Reference Network: instrumentation, uncertainty analysis, and recommendations for future high-accuracy greenhouse gas monitoring efforts", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {7}({2}), pp. 647-687. |
| Abstract: A reliable and precise in situ CO2 and CO analysis system has been developed and deployed at eight sites in the NOAA Earth System Research Laboratory's (ESRL) Global Greenhouse Gas Reference Network. The network uses very tall (> 300 m) television and radio transmitter towers that provide a convenient platform for mid-boundary-layer trace-gas sampling. Each analyzer has three sample inlets for profile sampling, and a complete vertical profile is obtained every 15 min. The instrument suite at one site has been augmented with a cavity ring-down spectrometer for measuring CO2 and CH4. The long-term stability of the systems in the field is typically better than 0.1 ppm for CO2, 6 ppb for CO, and 0.5 ppb for CH4, as determined from repeated standard gas measurements. The instrumentation is fully automated and includes sensors for measuring a variety of status parameters, such as temperatures, pressures, and flow rates, that are inputs for automated alerts and quality control algorithms. Detailed and time-dependent uncertainty estimates have been constructed for all of the gases, and the uncertainty framework could be readily adapted to other species or analysis systems. The design emphasizes use of off-theshelf parts and modularity to facilitate network operations and ease of maintenance. The systems report high-quality data with > 93% uptime. Recurrent problems and limitations of the current system are discussed along with general recommendations for high-accuracy trace-gas monitoring. The network is a key component of the North American Carbon Program and a useful model for future research-grade operational greenhouse gas monitoring efforts. |
BibTeX:
@article{andrews14a,
author = {Andrews, A. E. and Kofler, J. D. and Trudeau, M. E. and Williams, J. C. and Neff, D. H. and Masarie, K. A. and Chao, D. Y. and Kitzis, D. R. and Novelli, P. C. and Zhao, C. L. and Dlugokencky, E. J. and Lang, P. M. and Crotwell, M. J. and Fischer, M. L. and Parker, M. J. and Lee, J. T. and Baumann, D. D. and Desai, A. R. and Stanier, C. O. and De Wekker, S. F. J. and Wolfe, D. E. and Munger, J. W. and Tans, P. P.},
title = {CO2, CO, and CH4 measurements from tall towers in the NOAA Earth System Research Laboratory's Global Greenhouse Gas Reference Network: instrumentation, uncertainty analysis, and recommendations for future high-accuracy greenhouse gas monitoring efforts},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2014},
volume = {7},
number = {2},
pages = {647--687},
doi = {10.5194/amt-7-647-2014}
}
|
| Babenhauserheide A, Basu S, Houweling S, Peters W and Butz A ({2015}), "Comparing the CarbonTracker and TM5-4DVar data assimilation systems for CO2 surface flux inversions", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({17}), pp. 9747-9763. |
| Abstract: Data assimilation systems allow for estimating surface fluxes of greenhouse gases from atmospheric concentration measurements. Good knowledge about fluxes is essential to understand how climate change affects ecosystems and to characterize feedback mechanisms. Based on the assimilation of more than 1 year of atmospheric in situ concentration measurements, we compare the performance of two established data assimilation models, CarbonTracker and TM5-4DVar (Transport Model 5 - Four-Dimensional Variational model), for CO2 flux estimation. CarbonTracker uses an ensemble Kalman filter method to optimize fluxes on ecoregions. TM5-4DVar employs a 4-D variational method and optimizes fluxes on a 6 degrees x 4 degrees longitude-latitude grid. Harmonizing the input data allows for analyzing the strengths and weaknesses of the two approaches by direct comparison of the modeled concentrations and the estimated fluxes. We further assess the sensitivity of the two approaches to the density of observations and operational parameters such as the length of the assimilation time window. Our results show that both models provide optimized CO2 concentration fields of similar quality. In Antarctica CarbonTracker underestimates the wintertime CO2 concentrations, since its 5-week assimilation window does not allow for adjusting the distant surface fluxes in response to the detected concentration mismatch. Flux estimates by CarbonTracker and TM5-4DVar are consistent and robust for regions with good observation coverage, regions with low observation coverage reveal significant differences. In South America, the fluxes estimated by TM5-4DVar suffer from limited representativeness of the few observations. For the North American continent, mimicking the historical increase of the measurement network density shows improving agreement between CarbonTracker and TM5-4DVar flux estimates for increasing observation density. |
BibTeX:
@article{babenhauserheide15a,
author = {Babenhauserheide, A. and Basu, S. and Houweling, S. and Peters, W. and Butz, A.},
title = {Comparing the CarbonTracker and TM5-4DVar data assimilation systems for CO2 surface flux inversions},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2015},
volume = {15},
number = {17},
pages = {9747--9763},
doi = {10.5194/acp-15-9747-2015}
}
|
| Badawy B, Polavarapu S, Jones DBA, Deng F, Neish M, Melton JR, Nassar R and Arora VK (2018), "Coupling the Canadian Terrestrial Ecosystem Model (CTEM v. 2.0) to Environment and Climate Change Canada's greenhouse gas forecast model (v.107-glb)", GEOSCIENTIFIC MODEL DEVELOPMENT., FEB 20, 2018. Vol. 11(2), pp. 631-663. |
| Abstract: The Canadian Land Surface Scheme and the Canadian Terrestrial Ecosystem Model (CLASS-CTEM) together form the land surface component in the family of Canadian Earth system models (CanESMs). Here, CLASS-CTEM is coupled to Environment and Climate Change Canada (ECCC)'s weather and greenhouse gas forecast model (GEM-MACH-GHG) to consistently model atmosphere-land exchange of CO2. The coupling between the land and the atmospheric transport model ensures consistency between meteorological forcing of CO2 fluxes and CO2 transport. The procedure used to spin up carbon pools for CLASS-CTEM for multi-decadal simulations needed to be significantly altered to deal with the limited availability of consistent meteorological information from a constantly changing operational environment in the GEM-MACH-GHG model. Despite the limitations in the spin-up procedure, the simulated fluxes obtained by driving the CLASS-CTEM model with meteorological forcing from GEM-MACH-GHG were comparable to those obtained from CLASS-CTEM when it is driven with standard meteorological forcing from the Climate Research Unit (CRU) combined with reanalysis fields from the National Centers for Environmental Prediction (NCEP) to form CRU-NCEP dataset. This is due to the similarity of the two meteorological datasets in terms of temperature and radiation. However, notable discrepancies in the seasonal variation and spatial patterns of precipitation estimates, especially in the tropics, were reflected in the estimated carbon fluxes, as they significantly affected the mag-nitude of the vegetation productivity and, to a lesser extent, the seasonal variations in carbon fluxes. Nevertheless, the simulated fluxes based on the meteorological forcing from the GEM-MACH-GHG model are consistent to some extent with other estimates from bottom-up or top-down approaches. Indeed, when simulated fluxes obtained by driving the CLASS-CTEM model with meteorological data from the GEM-MACH-GHG model are used as prior estimates for an atmospheric CO2 inversion analysis using the adjoint of the GEOS-Chem model, the retrieved CO2 flux estimates are comparable to those obtained from other systems in terms of the global budget and the total flux estimates for the northern extratropical regions, which have good observational coverage. In data-poor regions, as expected, differences in the retrieved fluxes due to the prior fluxes become apparent. Coupling CLASS-CTEM into the Environment Canada Carbon Assimilation System (EC-CAS) is considered an important step toward understanding how meteorological uncertainties affect both CO2 flux estimates and modeled atmospheric transport. Ultimately, such an approach will provide more direct feedback to the CLASS-CTEM developers and thus help to improve the performance of CLASS-CTEM by identifying the model limitations based on atmospheric constraints. |
BibTeX:
@article{badawy18a,
author = {Badawy, Bakr and Polavarapu, Saroja and Jones, Dylan B. A. and Deng, Feng and Neish, Michael and Melton, Joe R. and Nassar, Ray and Arora, Vivek K.},
title = {Coupling the Canadian Terrestrial Ecosystem Model (CTEM v. 2.0) to Environment and Climate Change Canada's greenhouse gas forecast model (v.107-glb)},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2018},
volume = {11},
number = {2},
pages = {631-663},
doi = {10.5194/gmd-11-631-2018}
}
|
| Baker IT, Denning AS and Stoeckli R ({2010}), "North American gross primary productivity: regional characterization and interannual variability", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 533-549. |
| Abstract: Seasonality and interannual variability in North American photosynthetic activity reflect potential patterns of climate variability. We simulate 24 yr (1983-2006) and evaluate regional and seasonal contribution to annual mean gross primary productivity (GPP) as well as its interannual variability. The highest productivity occurs in Mexico, the southeast United States and the Pacific Northwest. Annual variability is largest in tropical Mexico, the desert Southwest and the Midwestern corridor. We find that no single region or season consistently determines continental annual GPP anomaly. GPP variability is dependent upon soil moisture availability in low- and mid-latitudes, and temperature in the north. Soil moisture is a better predictor than precipitation as it integrates precipitation events temporally. The springtime anomaly is the most frequent seasonal contributor to the annual GPP variability. No climate mode (i.e. ENSO, NAM) can be associated with annual or seasonal variability over the entire continent. We define a region extending from the Northeast United States through the midwest and into the southwestern United States and northern Mexico that explains a significant fraction of the variability in springtime GPP. We cannot correlate this region to a single mechanism (i.e. temperature, precipitation or soil moisture) or mode of climate variability. |
BibTeX:
@article{baker10a,
author = {Baker, Ian T. and Denning, A. Scott and Stoeckli, Reto},
title = {North American gross primary productivity: regional characterization and interannual variability},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2010},
volume = {62},
number = {5, SI},
pages = {533--549},
doi = {10.1111/j.1600-0889.2010.00492.x}
}
|
| Ballantyne AP, Miller JB and Tans PP ({2010}), "Apparent seasonal cycle in isotopic discrimination of carbon in the atmosphere and biosphere due to vapor pressure deficit", GLOBAL BIOGEOCHEMICAL CYCLES., SEP 10, {2010}. Vol. {24} |
| Abstract: We explore seasonal variability in isotopic fractionation by analyzing observational data from the atmosphere and the biosphere, as well as simulated data from a global model. Using simulated values of atmospheric CO2 and its carbon isotopic composition, we evaluated different methods for specifying background concentrations when calculating the isotopic signature of source CO2 (delta(s)) to the atmosphere. Based on this evaluation, we determined that free troposphere measurements should be used when available as a background reference when calculating delta(s) from boundary layer observations. We then estimate the seasonal distribution of delta(s) from monthly climatologies derived from several atmospheric sampling sites. This approach yields significant seasonal variations in delta(s) with more enriched values during the summer months that exceed the uncertainty of delta(s) estimated for any given month. Intra-annual measurements of delta C-13 in the cellulose of Pinus taeda growing in the southeastern U.S. also reveal seasonal isotopic variations that are consistent in phase but not necessarily amplitude with atmospherically derived estimates of delta(s). Coherent seasonal patterns in delta(s) inferred from the atmosphere and observed in the biosphere were not consistent with the seasonal isotopic discrimination simulated by a commonly used biosphere model. However, delta(s) seasonality consistent with observations from the atmosphere and biosphere was retrieved with a revised biosphere model when stomatal conductance, and thus isotopic discrimination, was allowed to vary in response to vapor pressure deficit rather than relative humidity. Therefore, in regions where vapor pressure deficit and relative humidity are positively covariant over the growth season, such as the sub-tropics, different stomatal conductance models may yield very different estimates of CO2 and H2O exchange between the biosphere and atmosphere. |
BibTeX:
@article{ballantyne10a,
author = {Ballantyne, A. P. and Miller, J. B. and Tans, P. P.},
title = {Apparent seasonal cycle in isotopic discrimination of carbon in the atmosphere and biosphere due to vapor pressure deficit},
journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
year = {2010},
volume = {24},
doi = {10.1029/2009GB003623}
}
|
| Barichivich J, Briffa KR, Osborn TJ, Melvin TM and Caesar J ({2012}), "Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere", GLOBAL BIOGEOCHEMICAL CYCLES., DEC 6, {2012}. Vol. {26} |
| Abstract: Gridded daily temperature from 1950 to 2011 and atmospheric CO2 concentration data from high-latitude observing stations and the CarbonTracker assimilation system are used to examine recent spatiotemporal variability of the thermal growing season and its relationship with seasonal biospheric carbon uptake and release in the Northern Hemisphere. The thermal growing season has lengthened substantially since 1950 but most of the lengthening has occurred during the last three decades (2.9 days decade(-1), p < 0.01 for 1980-2011), with stronger rates of extension in Eurasia (4.0 days decade(-1), p < 0.01) than in North America (1.2 days decade(-1), p > 0.05). Unlike most previous studies, which had more limited data coverage over the past decade, we find that strong autumn warming of about 1 degrees C during the second half of the 2000s has led to a significant shift toward later termination of the thermal growing season, resulting in the longest potential growing seasons since 1950. On average, the thermal growing season has extended symmetrically by about a week during this period, starting some 4.0 days earlier and ending about 4.3 days later. The earlier start of the thermal growing season is associated with earlier onset of the biospheric carbon uptake period at high northern latitudes. In contrast, later termination of the growing season is associated with earlier termination of biospheric carbon uptake, but this relationship appears to have decoupled since the beginning of the period of strong autumn warming during the second half of the 2000s. Therefore, owing to these contrasting biospheric responses at the margins of the growing season, the current extension in the thermal growing season length has not led to a concomitant extension of the period of biospheric carbon uptake. |
BibTeX:
@article{barichivich12a,
author = {Barichivich, J. and Briffa, K. R. and Osborn, T. J. and Melvin, T. M. and Caesar, J.},
title = {Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere},
journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
year = {2012},
volume = {26},
doi = {10.1029/2012GB004312}
}
|
| (2018), "Detection and attribution of carbon cycle processes from atmospheric O2 and CO2 measurements at Halley Research Station, Antarctica and Weybourne Atmospheric Observatory, U.K." UNIVERSITY OF EAST ANGLIA, U.K..
[BibTeX] |
BibTeX:
@phdthesis{barningham18a,,
title = {Detection and attribution of carbon cycle processes from atmospheric O2 and CO2 measurements at Halley Research Station, Antarctica and Weybourne Atmospheric Observatory, U.K.},
publisher = {UNIVERSITY OF EAST ANGLIA, U.K.},
year = {2018}
}
|
| Barthlott S, Schneider M, Hase F, Wiegele A, Christner E, Gonzalez Y, Blumenstock T, Dohe S, Garcia OE, Sepulveda E, Strong K, Mendonca J, Weaver D, Palm M, Deutscher NM, Warneke T, Notholt J, Lejeune B, Mahieu E, Jones N, Griffith DWT, Velazco VA, Smale D, Robinson J, Kivi R, Heikkinen P and Raffalski U ({2015}), "Using XCO2 retrievals for assessing the long-term consistency of NDACC/FTIR data sets", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({3}), pp. 1555-1573. |
| Abstract: Within the NDACC (Network for the Detection of Atmospheric Composition Change), more than 20 FTIR (Fourier-transform infrared) spectrometers, spread worldwide, provide long-term data records of many atmospheric trace gases. We present a method that uses measured and modelled XCO2 for assessing the consistency of these NDACC data records. Our XCO2 retrieval setup is kept simple so that it can easily be adopted for any NDACC/FTIR-like measurement made since the late 1950s. By a comparison to coincident TCCON (Total Carbon Column Observing Network) measurements, we empirically demonstrate the useful quality of this suggested NDACC XCO2 product (empirically obtained scatter between TCCON and NDACC is about 4 parts per thousand for daily mean as well as monthly mean comparisons, and the bias is 25 parts per thousand). Our XCO2 model is a simple regression model fitted to CarbonTracker results and the Mauna Loa CO2 in situ records. A comparison to TCCON data suggests an uncertainty of the model for monthly mean data of below 3 parts per thousand. We apply the method to the NDACC/FTIR spectra that are used within the project MUSICA (multi-platform remote sensing of isotopologues for investigating the cycle of atmospheric water) and demonstrate that there is a good consistency for these globally representative set of spectra measured since 1996: the scatter between the modelled and measured XCO2 on a yearly time scale is only 3 parts per thousand. |
BibTeX:
@article{barthlott15a,
author = {Barthlott, S. and Schneider, M. and Hase, F. and Wiegele, A. and Christner, E. and Gonzalez, Y. and Blumenstock, T. and Dohe, S. and Garcia, O. E. and Sepulveda, E. and Strong, K. and Mendonca, J. and Weaver, D. and Palm, M. and Deutscher, N. M. and Warneke, T. and Notholt, J. and Lejeune, B. and Mahieu, E. and Jones, N. and Griffith, D. W. T. and Velazco, V. A. and Smale, D. and Robinson, J. and Kivi, R. and Heikkinen, P. and Raffalski, U.},
title = {Using XCO2 retrievals for assessing the long-term consistency of NDACC/FTIR data sets},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2015},
volume = {8},
number = {3},
pages = {1555--1573},
doi = {10.5194/amt-8-1555-2015}
}
|
| Basu S, Houweling S, Peters W, Sweeney C, Machida T, Maksyutov S, Patra PK, Saito R, Chevallier F, Niwa Y, Matsueda H and Sawa Y ({2011}), "The seasonal cycle amplitude of total column CO2: Factors behind the model-observation mismatch", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 15, {2011}. Vol. {116} |
| Abstract: CO2 surface fluxes that are statistically consistent with surface layer measurements of CO2, when propagated forward in time by atmospheric transport models, underestimate the seasonal cycle amplitude of total column CO2 in the northern temperate latitudes by 1-2 ppm. In this paper we verify the systematic nature of this underestimation at a number of Total Carbon Column Observation Network (TCCON) stations by comparing their measurements with a number of transport models. In particular, at Park Falls, Wisconsin (United States), we estimate this mismatch to be 1.4 ppm and try to attribute portions of this mismatch to different factors affecting the total column. We find that errors due to (1) the averaging kernel and prior profile used in forward models, (2) water vapor in the model atmosphere, (3) incorrect vertical transport by transport models in the free troposphere, (4) incorrect aging of air in transport models in the stratosphere, and (5) air mass dependence in TCCON data can explain up to 1 ppm of this mismatch. The remaining 0.4 ppm mismatch is at the edge of the <= 0.4 ppm accuracy requirement on satellite measurements to improve on our current estimate of surface fluxes. Uncertainties in the biosphere fluxes driving the transport models could explain a part of the remaining 0.4 ppm mismatch, implying that with corrections to the factors behind the accounted-for 1 ppm underestimation, present inverse modeling frameworks could effectively assimilate satellite CO2 measurements. |
BibTeX:
@article{basu11a,
author = {Basu, Sourish and Houweling, Sander and Peters, Wouter and Sweeney, Colm and Machida, Toshinobu and Maksyutov, Shamil and Patra, Prabir K. and Saito, Ryu and Chevallier, Frederic and Niwa, Yosuke and Matsueda, Hidekazu and Sawa, Yousuke},
title = {The seasonal cycle amplitude of total column CO2: Factors behind the model-observation mismatch},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2011JD016124}
}
|
| Basu S, Guerlet S, Butz A, Houweling S, Hasekamp O, Aben I, Krummel P, Steele P, Langenfelds R, Torn M, Biraud S, Stephens B, Andrews A and Worthy D ({2013}), "Global CO2 fluxes estimated from GOSAT retrievals of total column CO2", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({17}), pp. 8695-8717. |
| Abstract: We present one of the first estimates of the global distribution of CO2 surface fluxes using total column CO2 measurements retrieved by the SRON-KIT RemoTeC algorithm from the Greenhouse gases Observing SATellite (GOSAT). We derive optimized fluxes from June 2009 to December 2010. We estimate fluxes from surface CO2 measurements to use as baselines for comparing GOSAT data-derived fluxes. Assimilating only GOSAT data, we can reproduce the observed CO2 time series at surface and TC-CON sites in the tropics and the northern extra-tropics. In contrast, in the southern extra-tropics GOSAT X-CO2 leads to enhanced seasonal cycle amplitudes compared to independent measurements, and we identify it as the result of a land-sea bias in our GOSAT X-CO2 retrievals. A bias correction in the form of a global offset between GOSAT land and sea pixels in a joint inversion of satellite and surface measurements of CO2 yields plausible global flux estimates which are more tightly constrained than in an inversion using surface CO2 data alone. We show that assimilating the biascorrected GOSAT data on top of surface CO2 data (a) reduces the estimated global land sink of CO2, and (b) shifts the terrestrial net uptake of carbon from the tropics to the extratropics. It is concluded that while GOSAT total column CO2 provide useful constraints for source-sink inversions, small spatiotemporal biases -beyond what can be detected using current validation techniques - have serious consequences for optimized fluxes, even aggregated over continental scales. |
BibTeX:
@article{basu13a,
author = {Basu, S. and Guerlet, S. and Butz, A. and Houweling, S. and Hasekamp, O. and Aben, I. and Krummel, P. and Steele, P. and Langenfelds, R. and Torn, M. and Biraud, S. and Stephens, B. and Andrews, A. and Worthy, D.},
title = {Global CO2 fluxes estimated from GOSAT retrievals of total column CO2},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {17},
pages = {8695--8717},
doi = {10.5194/acp-13-8695-2013}
}
|
| Basu S, Miller JB and Lehman S ({2016}), "Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and (CO2)-C-14 measurements: Observation System Simulations", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {16}({9}), pp. 5665-5683. |
| Abstract: National annual total CO2 emissions from combustion of fossil fuels are likely known to within 5-10aEuro-% for most developed countries. However, uncertainties are inevitably larger (by unknown amounts) for emission estimates at regional and monthly scales, or for developing countries. Given recent international efforts to establish emission reduction targets, independent determination and verification of regional and national scale fossil fuel CO2 emissions are likely to become increasingly important. Here, we take advantage of the fact that precise measurements of C-14 in CO2 provide a largely unbiased tracer for recently added fossil-fuel-derived CO2 in the atmosphere and present an atmospheric inversion technique to jointly assimilate observations of CO2 and (CO2)-C-14 in order to simultaneously estimate fossil fuel emissions and biospheric exchange fluxes of CO2. Using this method in a set of Observation System Simulation Experiments (OSSEs), we show that given the coverage of (CO2)-C-14 measurements available in 2010 (969 over North America, 1063 globally), we can recover the US national total fossil fuel emission to better than 1aEuro-% for the year and to within 5aEuro-% for most months. Increasing the number of (CO2)-C-14 observations to similar to 5000 per year over North America, as recently recommended by the National Academy of Science (NAS) (Pacala et al., 2010), we recover monthly emissions to within 5aEuro-% for all months for the US as a whole and also for smaller, highly emissive regions over which the specified data coverage is relatively dense, such as for the New England states or the NY-NJ-PA tri-state area. This result suggests that, given continued improvement in state-of-the art transport models, a measurement program similar in scale to that recommended by the NAS can provide for independent verification of bottom-up inventories of fossil fuel CO2 at the regional and national scale. In addition, we show that the dual tracer inversion framework can detect and minimize biases in estimates of the biospheric flux that would otherwise arise in a traditional CO2-only inversion when prescribing fixed but inaccurate fossil fuel fluxes. |
BibTeX:
@article{basu16a,
author = {Basu, Sourish and Miller, John Bharat and Lehman, Scott},
title = {Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and (CO2)-C-14 measurements: Observation System Simulations},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2016},
volume = {16},
number = {9},
pages = {5665--5683},
doi = {10.5194/acp-16-5665-2016}
}
|
| Belikov DA, Bril A, Maksyutov S, Oshchepkov S, Saeki T, Takagi H, Yoshida Y, Ganshin A, Zhuravlev R, Aoki S and Yokota T ({2014}), "Column-averaged CO2 concentrations in the subarctic from GOSAT retrievals and NIES transport model simulations", POLAR SCIENCE., JUN, {2014}. Vol. {8}({2, SI}), pp. 129-145. |
| Abstract: The distribution of atmospheric carbon dioxide (CO2) in the subarctic was investigated using the National Institute for Environmental Studies (NIBS) three-dimensional transport model (TM) and retrievals from the Greenhouse gases Observing SATellite (GOSAT). Column-averaged dry air mole fractions of subarctic atmospheric CO2 (XCO2) from the NIES TM for four flux combinations were analyzed. Two flux datasets were optimized using only surface observations and two others were optimized using both surface and GOSAT Level 2 data. Two inverse modeling approaches using GOSAT data were compared. In the basic approach adopted in the GOSAT Level 4 product, the GOSAT observations are aggregated into monthly means over 5 degrees x 5 degrees grids. In the alternative method, the model observation misfit is estimated for each observation separately. The XCO2 values simulated with optimized fluxes were validated against Total Carbon Column Observing Network (TCCON) ground-based high-resolution Fourier Transform Spectrometer (FTS) measurements. Optimized fluxes were applied to study XCO2 seasonal variability over the period 2009-2010 in the Arctic and subarctic regions. The impact on CO2 levels of emissions from enhancement of biospheric respiration induced by the high temperature and strong wildfires occurring in the summer of 2010 was analyzed. Use of GOSAT data has a substantial impact on estimates of the level of CO2 interanual variability. (C) 2014 Elsevier B.V. and NIPR. All rights reserved. |
BibTeX:
@article{belikov14a,
author = {Belikov, D. A. and Bril, A. and Maksyutov, S. and Oshchepkov, S. and Saeki, T. and Takagi, H. and Yoshida, Y. and Ganshin, A. and Zhuravlev, R. and Aoki, S. and Yokota, T.},
title = {Column-averaged CO2 concentrations in the subarctic from GOSAT retrievals and NIES transport model simulations},
journal = {POLAR SCIENCE},
year = {2014},
volume = {8},
number = {2, SI},
pages = {129--145},
doi = {10.1016/j.polar.2014.02.002}
}
|
| Belikov DA, Maksyutov S, Yaremchuk A, Ganshin A, Kaminski T, Blessing S, Sasakawa M, Gomez-Pelaez AJ and Starchenko A ({2016}), "Adjoint of the global Eulerian-Lagrangian coupled atmospheric transport model (A-GELCA v1.0): development and validation", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {9}({2}), pp. 749-764. |
| Abstract: We present the development of the Adjoint of the Global Eulerian-Lagrangian Coupled Atmospheric (A-GELCA) model that consists of the National Institute for Environmental Studies (NIES) model as an Eulerian three-dimensional transport model (TM), and FLEXPART (FLEXible PARTicle dispersion model) as the Lagrangian Particle Dispersion Model (LPDM). The forward tangent linear and adjoint components of the Eulerian model were constructed directly from the original NIES TM code using an automatic differentiation tool known as TAF (Transformation of Algorithms in Fortran; http://www.FastOpt.com), with additional manual pre- and post-processing aimed at improving transparency and clarity of the code and optimizing the performance of the computing, including MPI (Message Passing Interface). The Lagrangian component did not require any code modification, as LPDMs are self-adjoint and track a significant number of particles backward in time in order to calculate the sensitivity of the observations to the neighboring emission areas. The constructed Eulerian adjoint was coupled with the Lagrangian component at a time boundary in the global domain. The simulations presented in this work were performed using the A-GELCA model in forward and adjoint modes. The forward simulation shows that the coupled model improves reproduction of the seasonal cycle and short-term variability of CO2. Mean bias and standard deviation for five of the six Siberian sites considered decrease roughly by 1 ppm when using the coupled model. The adjoint of the Eulerian model was shown, through several numerical tests, to be very accurate (within machine epsilon with mismatch around to +/- 6 e(-14)) compared to direct forward sensitivity calculations. The developed adjoint of the coupled model combines the flux conservation and stability of an Eulerian discrete adjoint formulation with the flexibility, accuracy, and high resolution of a Lagrangian backward trajectory formulation. A-GELCA will be incorporated into a variational inversion system designed to optimize surface fluxes of greenhouse gases. |
BibTeX:
@article{belikov16a,
author = {Belikov, Dmitry A. and Maksyutov, Shamil and Yaremchuk, Alexey and Ganshin, Alexander and Kaminski, Thomas and Blessing, Simon and Sasakawa, Motoki and Gomez-Pelaez, Angel J. and Starchenko, Alexander},
title = {Adjoint of the global Eulerian-Lagrangian coupled atmospheric transport model (A-GELCA v1.0): development and validation},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2016},
volume = {9},
number = {2},
pages = {749--764},
doi = {10.5194/gmd-9-749-2016}
}
|
| Berberoglu H, Gomez PS and Pilon L ({2009}), "Radiation characteristics of Botryococcus braunii, Chlorococcum littorale, and Chlorella sp. used for CO2 fixation and biofuel production", JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER., NOV, {2009}. Vol. {110}({17}), pp. 1879-1893. |
| Abstract: This paper reports experimental measurements of the radiation characteristics of green algae Used for carbon dioxide fixation via photosynthesis. The generated biomass can be used to produce not only biofuels but also feed for animal and food supplements for human consumptions. Particular attention was paid to three widely used species namely Botryococcus braunii, Chlorella sp., and Chlorococcum littorale. Their extinction and absorption coefficients were obtained from normal-normal and normal-hemispherical transmittance measurements over the spectral range from 400 to 800 nm. Moreover, a polar nephelometer was used to measure the scattering phase function of the microorganisms at 632.8 nm. It was observed that for all strains, scattering dominates over absorption. The magnitudes of the extinction and scattering cross-section are functions of the size, shape, and chlorophyll content of each strain in a nontrivial manner. Absorption peaks at 435,475, and 676 nm corresponding to chlorophyll a and chlorophyll b. The results can be used for scaling and optimization of CO2 fixation in ponds or photobioreactors as well as in the development of controlled ecological life support systems. (C) 2009 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{berberoglu09a,
author = {Berberoglu, Halil and Gomez, Pedro S. and Pilon, Laurent},
title = {Radiation characteristics of Botryococcus braunii, Chlorococcum littorale, and Chlorella sp. used for CO2 fixation and biofuel production},
journal = {JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER},
year = {2009},
volume = {110},
number = {17},
pages = {1879--1893},
doi = {10.1016/j.jqsrt.2009.04.005}
}
|
| Bergamaschi P, Frankenberg C, Meirink JF, Krol M, Villani MG, Houweling S, Dentener F, Dlugokencky EJ, Miller JB, Gatti LV, Engel A and Levin I ({2009}), "Inverse modeling of global and regional CH4 emissions using SCIAMACHY satellite retrievals", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 17, {2009}. Vol. {114} |
| Abstract: Methane retrievals from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument onboard ENVISAT provide important information on atmospheric CH4 sources, particularly in tropical regions which are poorly monitored by in situ surface observations. Recently, Frankenberg et al. (2008a, 2008b) reported a major revision of SCIAMACHY retrievals due to an update of spectroscopic parameters of water vapor and CH4. Here, we analyze the impact of this revision on global and regional CH4 emissions estimates in 2004, using the TM5-4DVAR inverse modeling system. Inversions based on the revised SCIAMACHY retrievals yield similar to 20% lower tropical emissions compared to the previous retrievals. The new retrievals improve significantly the consistency between observed and assimilated column average mixing ratios and the agreement with independent validation data. Furthermore, the considerable latitudinal and seasonal bias correction of the previous SCIAMACHY retrievals, derived in the TM5-4DVAR system by simultaneously assimilating high-accuracy surface measurements, is reduced by a factor of similar to 3. The inversions result in significant changes in the spatial patterns of emissions and their seasonality compared to the bottom-up inventories. Sensitivity tests were done to analyze the robustness of retrieved emissions, revealing some dependence on the applied a priori emission inventories and OH fields. Furthermore, we performed a detailed validation of simulated CH4 mixing ratios using NOAA ship and aircraft profile samples, as well as stratospheric balloon samples, showing overall good agreement. We use the new SCIAMACHY retrievals for a regional analysis of CH4 emissions from South America, Africa, and Asia, exploiting the zooming capability of the TM5 model. This allows a more detailed analysis of spatial emission patterns and better comparison with aircraft profiles and independent regional emission estimates available for South America. Large CH4 emissions are attributed to various wetland regions in tropical South America and Africa, seasonally varying and opposite in phase with CH4 emissions from biomass burning. India, China and South East Asia are characterized by pronounced emissions from rice paddies peaking in the third quarter of the year, in addition to further anthropogenic emissions throughout the year. |
BibTeX:
@article{bergamaschi09a,
author = {Bergamaschi, Peter and Frankenberg, Christian and Meirink, Jan Fokke and Krol, Maarten and Villani, M. Gabriella and Houweling, Sander and Dentener, Frank and Dlugokencky, Edward J. and Miller, John B. and Gatti, Luciana V. and Engel, Andreas and Levin, Ingeborg},
title = {Inverse modeling of global and regional CH4 emissions using SCIAMACHY satellite retrievals},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2009},
volume = {114},
doi = {10.1029/2009JD012287}
}
|
| Bergamaschi P, Houweling S, Segers A, Krol M, Frankenberg C, Scheepmaker RA, Dlugokencky E, Wofsy SC, Kort EA, Sweeney C, Schuck T, Brenninkmeijer C, Chen H, Beck V and Gerbig C ({2013}), "Atmospheric CH4 in the first decade of the 21st century: Inverse modeling analysis using SCIAMACHY satellite retrievals and NOAA surface measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUL 16, {2013}. Vol. {118}({13}), pp. 7350-7369. |
| Abstract: The causes of renewed growth in the atmospheric CH4 burden since 2007 are still poorly understood and subject of intensive scientific discussion. We present a reanalysis of global CH4 emissions during the 2000s, based on the TM5-4DVAR inverse modeling system. The model is optimized using high-accuracy surface observations from NOAA ESRL's global air sampling network for 2000-2010 combined with retrievals of column-averaged CH4 mole fractions from SCIAMACHY onboard ENVISAT (starting 2003). Using climatological OH fields, derived global total emissions for 2007-2010 are 16-20 Tg CH4/yr higher compared to 2003-2005. Most of the inferred emission increase was located in the tropics (9-14 Tg CH4/yr) and mid- latitudes of the northern hemisphere (6-8 Tg CH4/yr), while no significant trend was derived for Arctic latitudes. The atmospheric increase can be attributed mainly to increased anthropogenic emissions, but the derived trend is significantly smaller than estimated in the EDGARv4.2 emission inventory. Superimposed on the increasing trend in anthropogenic CH4 emissions are significant inter-annual variations (IAV) of emissions from wetlands (up to +/- 10 Tg CH4/yr), and biomass burning (up to +/- 7 Tg CH4/yr). Sensitivity experiments, which investigated the impact of the SCIAMACHY observations (versus inversions using only surface observations), of the OH fields used, and of a priori emission inventories, resulted in differences in the detailed latitudinal attribution of CH4 emissions, but the IAV and trends aggregated over larger latitude bands were reasonably robust. All sensitivity experiments show similar performance against independent shipboard and airborne observations used for validation, except over Amazonia where satellite retrievals improved agreement with observations in the free troposphere. |
BibTeX:
@article{bergamaschi13a,
author = {Bergamaschi, P. and Houweling, S. and Segers, A. and Krol, M. and Frankenberg, C. and Scheepmaker, R. A. and Dlugokencky, E. and Wofsy, S. C. and Kort, E. A. and Sweeney, C. and Schuck, T. and Brenninkmeijer, C. and Chen, H. and Beck, V. and Gerbig, C.},
title = {Atmospheric CH4 in the first decade of the 21st century: Inverse modeling analysis using SCIAMACHY satellite retrievals and NOAA surface measurements},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2013},
volume = {118},
number = {13},
pages = {7350--7369},
doi = {10.1002/jgrd.50480}
}
|
| Berry JA ({2012}), "There Ought to Be an Equation for That", Annual Review of Plant Biology., In ANNUAL REVIEW OF PLANT BIOLOGY, VOL 63. Vol. {63}(1), pp. 1-17. |
| Abstract: An overriding interest in photosynthesis has propelled my wanderings from chemist to biochemist to plant physiologist and on to global topics. Equations and models have been organizing principles along the way. This fascination started as a reaction to difficulties with written communication, but it has proven to be quite useful in moving across different levels of organization. I conclude with some discussion of the importance of Earth system models for understanding and predicting how human activities may influence the climate, environment, and biota in the future, and some ideas about how disciplinary science might make larger contributions to this interdisciplinary problem. |
BibTeX:
@article{berry12a,
author = {Berry, Joseph A.},
editor = {Merchant, SS},
title = {There Ought to Be an Equation for That},
booktitle = {ANNUAL REVIEW OF PLANT BIOLOGY, VOL 63},
journal = {Annual Review of Plant Biology},
year = {2012},
volume = {63},
number = {1},
pages = {1--17},
doi = {10.1146/annurev-arplant-042811-105547}
}
|
| Biavati G, Feist DG, Gerbig C and Kretschmer R ({2015}), "Error estimation for localized signal properties: application to atmospheric mixing height retrievals", Atmospheric Measurement Techniques. Vol. {8}({10}), pp. 4215-4230. |
| Abstract: The mixing height is a key parameter for many applications that relate surface-atmosphere exchange fluxes to atmospheric mixing ratios, e.g., in atmospheric transport modeling of pollutants. The mixing height can be estimated with various methods: profile measurements from radiosondes as well as remote sensing (e.g., optical backscatter measurements). For quantitative applications, it is important to estimate not only the mixing height itself but also the uncertainty associated with this estimate. However, classical error propagation typically fails on mixing height estimates that use thresholds in vertical profiles of some measured or measurement-derived quantity. Therefore, we propose a method to estimate the uncertainty of an estimation of the mixing height. The uncertainty we calculate is related not to the physics of the boundary layer (e.g., entrainment zone thickness) but to the quality of the analyzed signals. The method relies on the concept of statistical confidence and on the knowledge of the measurement errors. It can also be applied to problems outside atmospheric mixing height retrievals where properties have to be assigned to a specific position, e.g., the location of a local extreme. |
BibTeX:
@article{biavati15a,
author = {Biavati, G. and Feist, D. G. and Gerbig, C. and Kretschmer, R.},
title = {Error estimation for localized signal properties: application to atmospheric mixing height retrievals},
journal = {Atmospheric Measurement Techniques},
year = {2015},
volume = {8},
number = {10},
pages = {4215--4230},
doi = {10.5194/amt-8-4215-2015}
}
|
| Biraud SC, Torn MS, Smith JR, Sweeney C, Riley WJ and Tans PP ({2013}), "A multi-year record of airborne CO2 observations in the US Southern Great Plains", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {6}({3}), pp. 751-763. |
| Abstract: We report on 10 yr of airborne measurements of atmospheric CO2 mole fraction from continuous and flask systems, collected between 2002 and 2012 over the Atmospheric Radiation Measurement Program Climate Research Facility in the US Southern Great Plains (SGP). These observations were designed to quantify trends and variability in atmospheric mole fraction of CO2 and other greenhouse gases with the precision and accuracy needed to evaluate ground-based and satellite-based column CO2 estimates, test forward and inverse models, and help with the interpretation of ground-based CO2 mole-fraction measurements. During flights, we measured CO2 and meteorological data continuously and collected flasks for a rich suite of additional gases: CO2, CO, CH4, N2O, (CO2)-C-13, carbonyl sulfide (COS), and trace hydrocarbon species. These measurements were collected approximately twice per week by small aircraft (Cessna 172 initially, then Cessna 206) on a series of horizontal legs ranging in altitude from 460 m to 5500 m a.m.s.l. Since the beginning of the program, more than 400 continuous CO2 vertical profiles have been collected (2007-2012), along with about 330 profiles from NOAA/ESRL 12-flask (2006-2012) and 284 from NOAA/ESRL 2-flask (2002-2006) packages for carbon cycle gases and isotopes. Averaged over the entire record, there were no systematic differences between the continuous and flask CO2 observations when they were sampling the same air, i.e., over the one-minute flask-sampling time. Using multiple technologies (a flask sampler and two continuous analyzers), we documented a mean difference of < 0.2 ppm between instruments. However, flask data were not equivalent in all regards; horizontal variability in CO2 mole fraction within the 5-10 min legs sometimes resulted in significant differences between flask and continuous measurement values for those legs, and the information contained in fine-scale variability about atmospheric transport was not captured by flask-based observations. The CO2 mole fraction trend at 3000 m a.m.s.l. was 1.91 ppm yr(-1) between 2008 and 2010, very close to the concurrent trend at Mauna Loa of 1.95 ppm yr(-1). The seasonal amplitude of CO2 mole fraction in the free troposphere (FT) was half that in the planetary boundary layer (PBL) (similar to 15 ppm vs. similar to 30 ppm) and twice that at Mauna Loa (approximately 8 ppm). The CO2 horizontal variability was up to 10 ppm in the PBL and less than 1 ppm at the top of the vertical profiles in the FT. |
BibTeX:
@article{biraud13a,
author = {Biraud, S. C. and Torn, M. S. and Smith, J. R. and Sweeney, C. and Riley, W. J. and Tans, P. P.},
title = {A multi-year record of airborne CO2 observations in the US Southern Great Plains},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2013},
volume = {6},
number = {3},
pages = {751--763},
doi = {10.5194/amt-6-751-2013}
}
|
| Bodesheim P, Jung M, Gans F, Mahecha MD and Reichstein M (2018), "Upscaled diurnal cycles of land-atmosphere fluxes: a new global half-hourly data product", Earth System Science Data., JUL 20, 2018. Vol. 10(3), pp. 1327-1365. |
| Abstract: Interactions between the biosphere and the atmosphere can be well characterized by fluxes between the two. In particular, carbon and energy fluxes play a major role in understanding biogeochemical processes on an ecosystem level or global scale. However, the fluxes can only be measured at individual sites, e.g., by eddy covariance towers, and an upscaling of these local observations is required to analyze global patterns. Previous work focused on upscaling monthly, 8-day, or daily average values, and global maps for each flux have been provided accordingly. In this paper, we raise the upscaling of carbon and energy fluxes between land and atmosphere to the next level by increasing the temporal resolution to subdaily timescales. We provide continuous half-hourly fluxes for the period from 2001 to 2014 at 0.5 degrees spatial resolution, which allows for analyzing diurnal cycles globally. The data set contains four fluxes: gross primary production (GPP), net ecosystem exchange (NEE), latent heat (LE), and sensible heat (H). We propose two prediction approaches for the diurnal cycles based on large-scale regression models and compare them in extensive cross-validation experiments using different sets of predictor variables. We analyze the results for a set of FLUXNET tower sites showing the suitability of our approaches for this upscaling task. Finally, we have selected one approach to calculate the global half-hourly data products based on predictor variables from remote sensing and meteorology at daily resolution as well as half-hourly potential radiation. In addition, we provide a derived product that only contains monthly average diurnal cycles, which is a lightweight version in terms of data storage that still allows studying the important characteristics of diurnal patterns globally. We recommend to primarily use these monthly average diurnal cycles, because they are less affected by the impacts of day-to-day variation, observation noise, and short-term fluctuations on subdaily timescales compared to the full half-hourly flux products. The global half-hourly data products are available at https://doi.org/10.17871/BACI.224. |
BibTeX:
@article{bodesheim18a,
author = {Bodesheim, Paul and Jung, Martin and Gans, Fabian and Mahecha, Miguel D. and Reichstein, Markus},
title = {Upscaled diurnal cycles of land-atmosphere fluxes: a new global half-hourly data product},
journal = {Earth System Science Data},
year = {2018},
volume = {10},
number = {3},
pages = {1327-1365},
doi = {10.5194/essd-10-1327-2018}
}
|
| Boland S, Bösch H, Brown L, Burrows J, Ciais P, Connor B, Crisp D, Denning S, Doney S, Engelen R and others (2009), "The need for atmospheric carbon dioxide measurements from space: Contributions from a rapid reflight of the Orbiting Carbon Observatory", White paper to NASA.
[BibTeX] |
BibTeX:
@article{boland09a,
author = {Boland, Stacey and Bösch, Hartmut and Brown, Linda and Burrows, John and Ciais, Philippe and Connor, Brian and Crisp, David and Denning, Scott and Doney, Scott and Engelen, Richard and others},
title = {The need for atmospheric carbon dioxide measurements from space: Contributions from a rapid reflight of the Orbiting Carbon Observatory},
journal = {White paper to NASA},
year = {2009}
}
|
| Bouche A, Beck-Winchatz B and Potosnak MJ ({2016}), "A high-altitude balloon platform for determining exchange of carbon dioxide over agricultural landscapes", ATMOSPHERIC MEASUREMENT TECHNIQUES., NOV 29, {2016}. Vol. {9}({12}), pp. 5707-5719. |
| Abstract: The exchange of carbon dioxide between the terrestrial biosphere and the atmosphere is a key process in the global carbon cycle. Given emissions from fossil fuel combustion and the appropriation of net primary productivity by human activities, understanding the carbon dioxide exchange of cropland agroecosystems is critical for evaluating future trajectories of climate change. In addition, human manipulation of agroecosystems has been proposed as a technique of removing carbon dioxide from the atmosphere via practices such as no-tillage and cover crops. We propose a novel method of measuring the exchange of carbon dioxide over croplands using a high-altitude balloon (HAB) platform. The HAB methodology measures two sequential vertical profiles of carbon dioxide mixing ratio, and the surface exchange is calculated using a fixed-mass column approach. This methodology is relatively inexpensive, does not rely on any assumptions besides spatial homogeneity (no horizontal advection) and provides data over a spatial scale between stationary flux towers and satellite-based inversion calculations. The HAB methodology was employed during the 2014 and 2015 growing seasons in central Illinois, and the results are compared to satellite-based NDVI values and a flux tower located relatively near the launch site in Bondville, Illinois. These initial favorable results demonstrate the utility of the methodology for providing carbon dioxide exchange data over a large (10-100 km) spatial area. One drawback is its relatively limited temporal coverage. While recruiting citizen scientists to perform the launches could provide a more extensive dataset, the HAB methodology is not appropriate for providing estimates of net annual carbon dioxide exchange. Instead, a HAB dataset could provide an important check for upscaling flux tower results and verifying satellite-derived exchange estimates. |
BibTeX:
@article{bouche16a,
author = {Bouche, Angie and Beck-Winchatz, Bernhard and Potosnak, Mark J.},
title = {A high-altitude balloon platform for determining exchange of carbon dioxide over agricultural landscapes},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2016},
volume = {9},
number = {12},
pages = {5707--5719},
doi = {10.5194/amt-9-5707-2016}
}
|
| Bovensmann H, Buchwitz M, Burrows JP, Reuter M, Krings T, Gerilowski K, Schneising O, Heymann J, Tretner A and Erzinger J ({2010}), "A remote sensing technique for global monitoring of power plant CO2 emissions from space and related applications", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {3}({4}), pp. 781-811. |
| Abstract: Carbon dioxide (CO2) is the most important anthropogenic greenhouse gas (GHG) causing global warming. The atmospheric CO2 concentration increased by more than 30% since pre-industrial times - primarily due to burning of fossil fuels - and still continues to increase. Reporting of CO2 emissions is required by the Kyoto protocol. Independent verification of reported emissions, which are typially not directly measured, by methods such as inverse modeling of measured atmospheric CO2 concentrations is currently not possible globally due to lack of appropriate observations. Existing satellite instruments such as SCIAMACHY/ENVISAT and TANSO/GOSAT focus on advancing our understanding of natural CO2 sources and sinks. The obvious next step for future generation satellites is to also constrain anthropogenic CO2 emissions. Here we present a promising satellite remote sensing concept based on spectroscopic measurements of reflected solar radiation and show, using power plants as an example, that strong localized CO2 point sources can be detected and their emissions quantified. This requires mapping the atmospheric CO2 column distribution at a spatial resolution of 2x2 km(2) with a precision of 0.5% (2 ppm) or better. We indicate that this can be achieved with existing technology. For a single satellite in sun-synchronous orbit with a swath width of 500 km, each power plant (PP) is overflown every 6 days or more frequent. Based on the MODIS cloud mask data product we conservatively estimate that typically 20 sufficiently cloud free overpasses per PP can be achieved every year. We found that for typical wind speeds in the range of 2-6 m/s the statistical uncertainty of the retrieved PP CO2 emission due to instrument noise is in the range 1.6-4.8MtCO(2)/yr for single overpasses. This corresponds to 12-36% of the emission of a mid-size PP (13 MtCO(2)/yr). We have also determined the sensitivity to parameters which may result in systematic errors such as atmospheric transport and aerosol related parameters. We found that the emission error depends linearly on wind speed, i.e., a 10% wind speed error results in a 10br> emission error, and that neglecting enhanced aerosol concentrations in the PP plume may result in errors in the range 0.2-2.5 MtCO(2)/yr, depending on PP aerosol emission. The discussed concept has the potential to contribute to an independent verification of reported anthropogenic CO2 emissions and therefore could be an important component of a future global anthropogenic GHG emission monitoring system. This is of relevance in the context of Kyoto protocol follow-on agreements but also allows detection and monitoring of a variety of other strong natural and anthropogenic CO2 and CH4 emitters. The investigated instrument is not limited to these applications as it has been specified to also deliver the data needed for global regional-scale CO2 and CH4 surface flux inverse modeling. |
BibTeX:
@article{bovensmann10a,
author = {Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Reuter, M. and Krings, T. and Gerilowski, K. and Schneising, O. and Heymann, J. and Tretner, A. and Erzinger, J.},
title = {A remote sensing technique for global monitoring of power plant CO2 emissions from space and related applications},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2010},
volume = {3},
number = {4},
pages = {781--811},
doi = {10.5194/amt-3-781-2010}
}
|
| Bowman K, Liu J, Bloom A, Parazoo N, Lee M, Jiang Z, Menemenlis D, Gierach M, Collatz G, Gurney K and others (2017), "Global and Brazilian carbon response to El Niño Modoki 2011--2010", Earth and Space Science. Vol. 4(10), pp. 637-660.
[BibTeX] |
BibTeX:
@article{bowman17a,
author = {Bowman, KW and Liu, J and Bloom, AA and Parazoo, NC and Lee, M and Jiang, Z and Menemenlis, D and Gierach, MM and Collatz, GJ and Gurney, KR and others},
title = {Global and Brazilian carbon response to El Niño Modoki 2011--2010},
journal = {Earth and Space Science},
year = {2017},
volume = {4},
number = {10},
pages = {637--660}
}
|
| Bozhinova DN (2015), "Interpreting plant-sampled?` 14CO2 to study regional anthropogenic CO2 signals in Europe" Wageningen University.
[BibTeX] |
BibTeX:
@book{bozhinova15a,
author = {Bozhinova, Denica Nikolaeva},
title = {Interpreting plant-sampled?` 14CO2 to study regional anthropogenic CO2 signals in Europe},
publisher = {Wageningen University},
year = {2015}
}
|
| Bril A, Oshchepkov S and Yokota T ({2009}), "Retrieval of atmospheric methane from high spectral resolution satellite measurements: a correction for cirrus cloud effects", APPLIED OPTICS., APR 10, {2009}. Vol. {48}({11}), pp. 2139-2148. |
| Abstract: We assessed the accuracy of methane (CH4) retrievals from synthetic radiance spectra particular to Greenhouse Gases Observing Satellite observations. We focused on estimating the CH4 vertical column amount from an atmosphere that includes thin cirrus clouds, taking into account uncertain meteorological conditions. A photon path-length probability density function (PPDF)-based method was adapted to correct for atmospheric scattering effects in CH4 retrievals. This method was shown to provide similar retrieval accuracy as compared to a carbon dioxide (CO2)-proxy-based correction approach. It infers some advantages of PPDF-based method for methane retrievals under high variability of CO2 abundance. (C) 2009 Optical Society of America |
BibTeX:
@article{bril09a,
author = {Bril, Andrey and Oshchepkov, Sergey and Yokota, Tatsuya},
title = {Retrieval of atmospheric methane from high spectral resolution satellite measurements: a correction for cirrus cloud effects},
journal = {APPLIED OPTICS},
year = {2009},
volume = {48},
number = {11},
pages = {2139--2148},
doi = {10.1364/AO.48.002139}
}
|
| Brioude J, Petron G, Frost GJ, Ahmadov R, Angevine WM, Hsie EY, Kim SW, Lee SH, McKeen SA, Trainer M, Fehsenfeld FC, Holloway JS, Peischl J, Ryerson TB and Gurney KR ({2012}), "A new inversion method to calculate emission inventories without a prior at mesoscale: Application to the anthropogenic CO2 emission from Houston, Texas", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 10, {2012}. Vol. {117} |
| Abstract: We developed a new inversion method to calculate an emission inventory for an anthropogenic pollutant without a prior emission estimate at mesoscale. This method employs slopes between mixing ratio enhancements of a given pollutant (CO2, for instance) with other co-emitted tracers in conjunction with the emission inventories of those tracers (CO, NOy, and SO2 are used in this example). The current application of this method employed in situ measurements onboard the NOAA WP-3 research aircraft during the 2006 Texas Air Quality Study (TexAQS 2006). We used 3 different transport models to estimate the uncertainties introduced by the transport models in the inversion. We demonstrated the validity of the new inversion method by calculating a 4 x 4 km(2) emission inventory of anthropogenic CO2 in the Houston area in Texas, and comparing it to the 10 x 10 km(2) Vulcan emission inventory for the same region. The calculated anthropogenic CO2 inventory for the Houston Ship Channel, home to numerous major industrial and port emission sources, showed excellent agreement with Vulcan. The daytime CO2 average flux from the Ship Channel is the largest urban CO2 flux reported in the literature. Compared to Vulcan, the daytime urban area CO2 emissions were higher by 37% +/- 6%. Those differences can be explained by uncertainties in emission factors in Vulcan and by increased emissions from point sources and on-road emitters between 2002, the reference year in Vulcan, and 2006, the year that the TexAQS observations were made. |
BibTeX:
@article{brioude12a,
author = {Brioude, J. and Petron, G. and Frost, G. J. and Ahmadov, R. and Angevine, W. M. and Hsie, E. -Y. and Kim, S. -W. and Lee, S. -H. and McKeen, S. A. and Trainer, M. and Fehsenfeld, F. C. and Holloway, J. S. and Peischl, J. and Ryerson, T. B. and Gurney, K. R.},
title = {A new inversion method to calculate emission inventories without a prior at mesoscale: Application to the anthropogenic CO2 emission from Houston, Texas},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2012},
volume = {117},
doi = {10.1029/2011JD016918}
}
|
| Brioude J, Angevine WM, Ahmadov R, Kim SW, Evan S, McKeen SA, Hsie EY, Frost GJ, Neuman JA, Pollack IB, Peischl J, Ryerson TB, Holloway J, Brown SS, Nowak JB, Roberts JM, Wofsy SC, Santoni GW, Oda T and Trainer M ({2013}), "Top-down estimate of surface flux in the Los Angeles Basin using a mesoscale inverse modeling technique: assessing anthropogenic emissions of CO, NOx and CO2 and their impacts", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({7}), pp. 3661-3677. |
| Abstract: We present top-down estimates of anthropogenic CO, NOx and CO2 surface fluxes at mesoscale using a Lagrangian model in combination with three different WRF model configurations, driven by data from aircraft flights during the CALNEX campaign in southern California in May-June 2010. The US EPA National Emission Inventory 2005 (NEI 2005) was the prior in the CO and NOx inversion calculations. The flux ratio inversion method, based on linear relationships between chemical species, was used to calculate the CO2 inventory without prior knowledge of CO2 surface fluxes. The inversion was applied to each flight to estimate the variability of single-flight-based flux estimates. In Los Angeles (LA) County, the uncertainties on CO and NOx fluxes were 10% and 15 respectively. Compared with NEI 2005, the CO posterior emissions were lower by 43% in LA County and by 37% in the South Coast Air Basin (SoCAB). NOx posterior emissions were lower by 32% in LA County and by 27% in the SoCAB. NOx posterior emissions were 40% lower on weekends relative to weekdays. The CO2 posterior estimates were 183 Tgyr(-1) in SoCAB. A flight during ITCT (Intercontinental Transport and Chemical Transformation) in 2002 was used to estimate emissions in the LA Basin in 2002. From 2002 to 2010, the CO and NOx posterior emissions decreased by 41% and 37 respectively, in agreement with previous studies. Over the same time period, CO2 emissions increased by 10% in LA County but decreased by 4% in the SoCAB, a statistically insignificant change. Overall, the posterior estimates were in good agreement with the California Air Resources Board (CARB) inventory, with differences of 15% or less. However, the posterior spatial distribution in the basin was significantly different from CARB for NOx emissions. WRF-Chem mesoscale chemical-transport model simulations allowed an evaluation of differences in chemistry using different inventory assumptions, including NEI 2005, a gridded CARB inventory and the posterior inventories derived in this study. The biases in WRF-Chem ozone were reduced and correlations were increased using the posterior from this study compared with simulations with the two bottom-up inventories, suggesting that improving the spatial distribution of ozone precursor surface emissions is also important in mesoscale chemistry simulations. |
BibTeX:
@article{brioude13a,
author = {Brioude, J. and Angevine, W. M. and Ahmadov, R. and Kim, S. -W. and Evan, S. and McKeen, S. A. and Hsie, E. -Y. and Frost, G. J. and Neuman, J. A. and Pollack, I. B. and Peischl, J. and Ryerson, T. B. and Holloway, J. and Brown, S. S. and Nowak, J. B. and Roberts, J. M. and Wofsy, S. C. and Santoni, G. W. and Oda, T. and Trainer, M.},
title = {Top-down estimate of surface flux in the Los Angeles Basin using a mesoscale inverse modeling technique: assessing anthropogenic emissions of CO, NOx and CO2 and their impacts},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {7},
pages = {3661--3677},
doi = {10.5194/acp-13-3661-2013}
}
|
| Brondfield MN, Hutyra LR, Gately CK, Raciti SM and Peterson SA ({2012}), "Modeling and validation of on-road CO2 emissions inventories at the urban regional scale", ENVIRONMENTAL POLLUTION., NOV, {2012}. Vol. {170}, pp. 113-123. |
| Abstract: On-road emissions are a major contributor to rising concentrations of atmospheric greenhouse gases. In this study, we applied a downscaling methodology based on commonly available spatial parameters to model on-road CO2 emissions at the 1 x 1 km scale for the Boston. MA region and tested our approach with surface-level CO2 observations. Using two previously constructed emissions inventories with differing spatial patterns and underlying data sources, we developed regression models based on impervious surface area and volume-weighted road density that could be scaled to any resolution. We found that the models accurately reflected the inventories at their original scales (R-2 = 0.63 for both models) and exhibited a strong relationship with observed CO2 mixing ratios when downscaled across the region. Moreover, the improved spatial agreement of the models over the original inventories confirmed that either product represents a viable basis for downscaling in other metropolitan regions, even with limited data. (c) 2012 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{brondfield12a,
author = {Brondfield, Max N. and Hutyra, Lucy R. and Gately, Conor K. and Raciti, Steve M. and Peterson, Scott A.},
title = {Modeling and validation of on-road CO2 emissions inventories at the urban regional scale},
journal = {ENVIRONMENTAL POLLUTION},
year = {2012},
volume = {170},
pages = {113--123},
doi = {10.1016/j.envpol.2012.06.003}
}
|
| Brooks BGJ, Desai AR, Stephens BB, Bowling DR, Burns SP, Watt AS, Heck SL and Sweeney C ({2012}), "Assessing filtering of mountaintop CO2 mole fractions for application to inverse models of biosphere-atmosphere carbon exchange", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({4}), pp. 2099-2115. |
| Abstract: There is a widely recognized need to improve our understanding of biosphere-atmosphere carbon exchanges in areas of complex terrain including the United States Mountain West. CO2 fluxes over mountainous terrain are often difficult to measure due to unusual and complicated influences associated with atmospheric transport. Consequently, deriving regional fluxes in mountain regions with carbon cycle inversion of atmospheric CO2 mole fraction is sensitive to filtering of observations to those that can be represented at the transport model resolution. Using five years of CO2 mole fraction observations from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON), five statistical filters are used to investigate a range of approaches for identifying regionally representative CO2 mole fractions. Test results from three filters indicate that subsets based on short-term variance and local CO2 gradients across tower inlet heights retain nine-tenths of the total observations and are able to define representative diel variability and seasonal cycles even for difficult-to-model sites where the influence of local fluxes is much larger than regional mole fraction variations. Test results from two other filters that consider measurements from previous and following days using spline fitting or sliding windows are overly selective. Case study examples showed that these windowing-filters rejected measurements representing synoptic changes in CO2, which suggests that they are not well suited to filtering continental CO2 measurements. We present a novel CO2 lapse rate filter that uses CO2 differences between levels in the model atmosphere to select subsets of site measurements that are representative on model scales. Our new filtering techniques provide guidance for novel approaches to assimilating mountain-top CO2 mole fractions in carbon cycle inverse models. |
BibTeX:
@article{brooks12a,
author = {Brooks, B. -G. J. and Desai, A. R. and Stephens, B. B. and Bowling, D. R. and Burns, S. P. and Watt, A. S. and Heck, S. L. and Sweeney, C.},
title = {Assessing filtering of mountaintop CO2 mole fractions for application to inverse models of biosphere-atmosphere carbon exchange},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2012},
volume = {12},
number = {4},
pages = {2099--2115},
doi = {10.5194/acp-12-2099-2012}
}
|
| Bruhwiler L, Dlugokencky E, Masarie K, Ishizawa M, Andrews A, Miller J, Sweeney C, Tans P and Worthy D ({2014}), "CarbonTracker-CH4: an assimilation system for estimating emissions of atmospheric methane", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({16}), pp. 8269-8293. |
| Abstract: We describe an assimilation system for atmospheric methane (CH4), CarbonTracker-CH4, and demonstrate the diagnostic value of global or zonally averaged CH4 abundances for evaluating the results. We show that CarbonTracker-CH4 is able to simulate the observed zonal average mole fractions and capture inter-annual variability in emissions quite well at high northern latitudes (53-90 degrees N). In contrast, CarbonTracker-CH4 is less successful in the tropics where there are few observations and therefore misses significant variability and is more influenced by prior flux estimates. CarbonTracker-CH4 estimates of total fluxes at high northern latitudes are about 81+/- 7 TgCH(4) yr-1, about 12 TgCH(4) yr-1 (13 lower than prior estimates, a result that is consistent with other atmospheric inversions. Emissions from European wetlands are decreased by 30 a result consistent with previous work by Bergamaschi et al. (2005); however, unlike their results, emissions from wetlands in boreal Eurasia are increased relative to the prior estimate. Although CarbonTracker-CH4 does not estimate an increasing trend in emissions from high northern latitudes for 2000 through 2010, significant inter-annual variability in high northern latitude fluxes is recovered. Exceptionally warm growing season temperatures in the Arctic occurred in 2007, a year that was also anonymously wet. Estimated emissions from natural sources were greater than the decadal average by 4.4+/- 3.8 TgCH(4) yr(-1) in 2007. CarbonTracker-CH4 estimates for temperate latitudes are only slightly increased over prior estimates, but about 10 TgCH(4) yr(-1) is redistributed from Asia to North America. This difference exceeds the estimated uncertainty for North America (+/- 3.5 TgCH(4) yr(-1)). We used time invariant prior flux estimates, so for the period from 2000 to 2006, when the growth rate of global atmospheric CH4 was very small, the assimilation does not produce increases in natural or anthropogenic emissions in contrast to bottom-up emission data sets. After 2006, when atmospheric CH4 began its recent increases, CarbonTracker-CH4 allocates some of the increases to anthropogenic emissions at temperate latitudes, and some to tropical wetland emissions. For temperate North America the prior flux increases by about 4 TgCH(4) yr(-1) during winter when biogenic emissions are small. Examination of the residuals at some North American observation sites suggests that increased gas and oil exploration may play a role since sites near fossil fuel production are particularly hard for the inversion to fit and the prior flux estimates at these sites are apparently lower and lower over time than what the atmospheric measurements imply. The tropics are not currently well resolved by CarbonTracker-CH4 due to sparse observational coverage and a short assimilation window. However, there is a small uncertainty reduction and posterior emissions are about 18% higher than prior estimates. Most of this increase is allocated to tropical South America rather than being distributed among the global tropics. Our estimates for this source region are about 32+/- 4 TgCH(4) yr(-1), in good agreement with the analysis of Melack et al. (2004) who obtained 29 TgCH(4) yr(-1) for the most productive region, the Amazon Basin. |
BibTeX:
@article{bruhwiler14a,
author = {Bruhwiler, L. and Dlugokencky, E. and Masarie, K. and Ishizawa, M. and Andrews, A. and Miller, J. and Sweeney, C. and Tans, P. and Worthy, D.},
title = {CarbonTracker-CH4: an assimilation system for estimating emissions of atmospheric methane},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2014},
volume = {14},
number = {16},
pages = {8269--8293},
doi = {10.5194/acp-14-8269-2014}
}
|
| Buchwitz M, Schneising O, Burrows JP, Bovensmann H, Reuter M and Notholt J ({2007}), "First direct observation of the atmospheric CO2 year-to-year increase from space", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {7}({16}), pp. 4249-4256.
[BibTeX] |
BibTeX:
@article{buchwitz07a,
author = {Buchwitz, M. and Schneising, O. and Burrows, J. P. and Bovensmann, H. and Reuter, M. and Notholt, J.},
title = {First direct observation of the atmospheric CO2 year-to-year increase from space},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2007},
volume = {7},
number = {16},
pages = {4249--4256}
}
|
| Buchwitz M, Reuter M, Schneising O, Heymann J, Bovensmann H and Burrows J (2009), "Towards an improved CO2 retrieval algorithm for SCIAMACHY on ENVISAT", In Proceedings Atmospheric Science Conference, Barcelona, Spain. , pp. 7-11.
[BibTeX] |
BibTeX:
@inproceedings{buchwitz09a,
author = {Buchwitz, M and Reuter, M and Schneising, O and Heymann, J and Bovensmann, H and Burrows, JP},
title = {Towards an improved CO2 retrieval algorithm for SCIAMACHY on ENVISAT},
booktitle = {Proceedings Atmospheric Science Conference, Barcelona, Spain},
year = {2009},
pages = {7--11}
}
|
| Buchwitz M, Bovensmann H, Burrows J, Schneising O and Reuter M (2010), "Global mapping of methane and carbon dioxide: from SCIAMACHY to CarbonSat", In Proceedings ESA-iLEAPS-EGU conference on earth observation for land-atmosphere interaction science, ESA Special Publications SP-688, ESRIN, Italy. , pp. 3-5. |
BibTeX:
@inproceedings{buchwitz10a,
author = {Buchwitz, M and Bovensmann, H and Burrows, JP and Schneising, O and Reuter, M},
title = {Global mapping of methane and carbon dioxide: from SCIAMACHY to CarbonSat},
booktitle = {Proceedings ESA-iLEAPS-EGU conference on earth observation for land-atmosphere interaction science, ESA Special Publications SP-688, ESRIN, Italy},
year = {2010},
pages = {3--5},
url = {http://tratin.cinvestav.mx/Portals/0/PapersADM/B/Buchwitz%20et%20al%202011%20global%20mapping%20sciamachy%20carbonsat.pdf}
}
|
| Buchwitz M, Reuter M, Schneising O, Boesch H, Aben I, Alexe M, Armante R, Bergamaschi P, Bovensmann H, Brunner D, Buchmann B, Burrows JP, Butz A, Chevallier F, Chedin A, Crevoisier CD, Gonzi S, De Maziere M, De Wachter E, Detmers R, Dils B, Frankenberg C, Hahne P, Hasekamp OP, Hewson W, Heymann J, Houweling S, Hilker M, Kaminski T, Kuhlmann G, Laeng A, v Leeuwen TT, Lichtenberg G, Marshall J, Noel S, Notholt J, Palmer P, Parker R, Scholze M, Stiller GP, Warneke T and Zehner C ({2015}), "THE GREENHOUSE GAS PROJECT OF ESA'S CLIMATE CHANGE INITIATIVE (GHG-CCI): OVERVIEW, ACHIEVEMENTS AND FUTURE PLANS", In 36TH INTERNATIONAL SYMPOSIUM ON REMOTE SENSING OF ENVIRONMENT. Vol. {47}({W3}), pp. 165-172. |
| Abstract: The GHG-CCI project (http://www.esa-ghg-cci.org/) is one of several projects of the European Space Agency's (ESA) Climate Change Initiative (CCI). The goal of the CCI is to generate and deliver data sets of various satellite-derived Essential Climate Variables (ECVs) in line with GCOS (Global Climate Observing System) requirements. The ``ECV Greenhouse Gases'' (ECV GHG) is the global distribution of important climate relevant gases - namely atmospheric CO2 and CH4 - with a quality sufficient to obtain information on regional CO2 and CH4 sources and sinks. The main goal of GHG-CCI is to generate long-term highly accurate and precise time series of global near-surface-sensitive satellite observations of CO2 and CH4, i.e., XCO2 and XCH4, starting with the launch of ESA's ENVISAT satellite. These products are currently retrieved from SCIAMACHY/ENVISAT (2002-2012) and TANSO-FTS/GOSAT (2009-today) nadir mode observations in the near-infrared/shortwave-infrared spectral region. In addition, other sensors (e.g., IASI and MIPAS) and viewing modes (e.g., SCIAMACHY solar occultation) are also considered and in the future also data from other satellites. The GHG-CCI data products and related documentation are freely available via the GHG-CCI website and yearly updates are foreseen. Here we present an overview about the latest data set (Climate Research Data Package No. 2 (CRDP2)) and summarize key findings from using satellite CO2 and CH4 retrievals to improve our understanding of the natural and anthropogenic sources and sinks of these important atmospheric greenhouse gases. We also shortly mention ongoing activities related to validation and initial user assessment of CRDP2 and future plans. |
BibTeX:
@inproceedings{buchwitz15a,
author = {Buchwitz, M. and Reuter, M. and Schneising, O. and Boesch, H. and Aben, I. and Alexe, M. and Armante, R. and Bergamaschi, P. and Bovensmann, H. and Brunner, D. and Buchmann, B. and Burrows, J. P. and Butz, A. and Chevallier, F. and Chedin, A. and Crevoisier, C. D. and Gonzi, S. and De Maziere, M. and De Wachter, E. and Detmers, R. and Dils, B. and Frankenberg, C. and Hahne, P. and Hasekamp, O. P. and Hewson, W. and Heymann, J. and Houweling, S. and Hilker, M. and Kaminski, T. and Kuhlmann, G. and Laeng, A. and v Leeuwen, T. T. and Lichtenberg, G. and Marshall, J. and Noel, S. and Notholt, J. and Palmer, P. and Parker, R. and Scholze, M. and Stiller, G. P. and Warneke, T. and Zehner, C.},
editor = {Schreier, G and Skrovseth, PE and Staudenrausch, H},
title = {THE GREENHOUSE GAS PROJECT OF ESA'S CLIMATE CHANGE INITIATIVE (GHG-CCI): OVERVIEW, ACHIEVEMENTS AND FUTURE PLANS},
booktitle = {36TH INTERNATIONAL SYMPOSIUM ON REMOTE SENSING OF ENVIRONMENT},
year = {2015},
volume = {47},
number = {W3},
pages = {165--172},
note = {36th International Symposium on Remote Sensing of the Environment (ISRSE), Berlin, GERMANY, MAY 11-15, 2015},
doi = {10.5194/isprsarchives-XL-7-W3-165-2015}
}
|
| Buchwitz M, Reuter M, Schneising O, Hewson W, Detmers RG, Boesch H, Hasekamp OP, Aben I, Bovensmann H, Burrows JP, Butz A, Chevallier F, Dils B, Frankenberg C, Heymann J, Lichtenberg G, De Maziere M, Notholt J, Parker R, Warneke T, Zehner C, Griffith DWT, Deutscher NM, Kuze A, Suto H and Wunch D ({2017}), "Global satellite observations of column-averaged carbon dioxide and methane: The GHG-CCI XCO2 and XCH4 CRDP3 data set", REMOTE SENSING OF ENVIRONMENT., DEC 15, {2017}. Vol. {203}, pp. 276-295. |
| Abstract: Carbon dioxide (CO2) and methane (CH4) are the two most important greenhouse gases emitted by mankind. Better knowledge of the surface sources and sinks of these Essential Climate Variables (ECVs) and related carbon uptake and release processes is needed for important climate change related applications such as improved climate modelling and prediction. Some satellites provide near-surface-sensitive atmospheric CO2 and CH4 observations that can be used to obtain information on CQ(2) and CH4 surface fluxes. The goal of the GHG-CCI project of the European Space Agency's (ESA) Climate Change Initiative (CCI) is to use satellite data to generate atmospheric CO2 and CH4 data products meeting demanding GCOS (Global Climate Observing System) greenhouse gas (GHG) ECV requirements. To achieve this, retrieval algorithms are regularly being improved followed by annual data reprocessing and analysis cycles to generate better products in terms of extended time series and continuously improved data quality. Here we present an overview about the latest GHG-CCI data set called Climate Research Data Package No.3 (CRDP3) focusing on the GHG-CCI core data products, which are column-averaged dry air mole fractions of CO2 and CH4, i.e., XCO2 and XCH4, as retrieved from SCIAMACHY/ENVISAT and TANSO/GOSAT satellite radiances covering the time period end of 2002 to end of 2014. We present global maps and time series including initial validation results obtained by comparisons with Total Carbon Column Observing Network (TCCON) ground-based observations. We show that the GCOS requirements for systematic error (<1 ppm for XCO2, <10 ppb for XCH4) and long-term stability (<0.2 ppm/year for XCO2, <2 ppb/year for XCH4) are met for nearly all products (an exception is SCIAMACHY methane especially since 2010). For XCO2 we present comparisons with global models using the output of two CO2 assimilation systems (MACC version 14r2 and CarbonTracker version CT2013B). We show that overall there is reasonable consistency and agreement between all data sets (within-1-2 ppm) but we also found significant differences depending on region and time period. (C) 2017 Elsevier Inc. All rights reserved. |
BibTeX:
@article{buchwitz17a,
author = {Buchwitz, M. and Reuter, M. and Schneising, O. and Hewson, W. and Detmers, R. G. and Boesch, H. and Hasekamp, O. P. and Aben, I. and Bovensmann, H. and Burrows, J. P. and Butz, A. and Chevallier, F. and Dils, B. and Frankenberg, C. and Heymann, J. and Lichtenberg, G. and De Maziere, M. and Notholt, J. and Parker, R. and Warneke, T. and Zehner, C. and Griffith, D. W. T. and Deutscher, N. M. and Kuze, A. and Suto, H. and Wunch, D.},
title = {Global satellite observations of column-averaged carbon dioxide and methane: The GHG-CCI XCO2 and XCH4 CRDP3 data set},
journal = {REMOTE SENSING OF ENVIRONMENT},
year = {2017},
volume = {203},
pages = {276--295},
doi = {10.1016/j.rse.2016.12.027}
}
|
| Buchwitz M, Reuter M, Schneising O, Noel S, Gier B, Bovensmann H, Burrows JP, Boesch H, Anand J, Parker RJ, Somkuti P, Detmers RG, Hasekamp OP, Aben I, Butz A, Kuze A, Suto H, Yoshida Y, Crisp D and O'Dell C ({2018}), "Computation and analysis of atmospheric carbon dioxide annual mean growth rates from satellite observations during 2003-2016", ATMOSPHERIC CHEMISTRY AND PHYSICS., DEC 7, {2018}. Vol. {18}({23}), pp. 17355-17370. |
| Abstract: The growth rate of atmospheric carbon dioxide (CO2) reflects the net effect of emissions and uptake resulting from anthropogenic and natural carbon sources and sinks. Annual mean CO2 growth rates have been determined from satellite retrievals of column-averaged dry-air mole fractions of CO2, i.e. XCO2, for the years 2003 to 2016. The XCO2 growth rates agree with National Oceanic and Atmospheric Administration (NOAA) growth rates from CO2 surface observations within the uncertainty of the satellite-derived growth rates (mean difference +/- standard deviation: 0.0 +/- 0.3 ppm year(-1); R: 0.82). This new and independent data set confirms record-large growth rates of around 3 ppm year(-1) in 2015 and 2016, which are attributed to the 2015-2016 El Nino. Based on a comparison of the satellite-derived growth rates with human CO2 emissions from fossil fuel combustion and with El Nino Southern Oscillation (ENSO) indices, we estimate by how much the impact of ENSO dominates the impact of fossil-fuel-burning-related emissions in explaining the variance of the atmospheric CO2 growth rate. Our analysis shows that the ENSO impact on CO2 growth rate variations dominates that of human emissions throughout the period 2003-2016 but in particular during the period 2010-2016 due to strong La Nina and El Nino events. Using the derived growth rates and their uncertainties, we estimate the probability that the impact of ENSO on the variability is larger than the impact of human emissions to be 63 % for the time period 2003-2016. If the time period is restricted to 2010-2016, this probability increases to 94%. |
BibTeX:
@article{buchwitz18a,
author = {Buchwitz, Michael and Reuter, Maximilian and Schneising, Oliver and Noel, Stefan and Gier, Bettina and Bovensmann, Heinrich and Burrows, John P. and Boesch, Hartmut and Anand, Jasdeep and Parker, Robert J. and Somkuti, Peter and Detmers, Rob G. and Hasekamp, Otto P. and Aben, Ilse and Butz, Andre and Kuze, Akihiko and Suto, Hiroshi and Yoshida, Yukio and Crisp, David and O'Dell, Christopher},
title = {Computation and analysis of atmospheric carbon dioxide annual mean growth rates from satellite observations during 2003-2016},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2018},
volume = {18},
number = {23},
pages = {17355--17370},
doi = {10.5194/acp-18-17355-2018}
}
|
| Burgin MS (2014), "Physics-based modeling for high-fidelity radar retrievals". Thesis at: University of Michigan.
[BibTeX] |
BibTeX:
@phdthesis{burgin14a,
author = {Burgin, Mariko Sofie},
title = {Physics-based modeling for high-fidelity radar retrievals},
school = {University of Michigan},
year = {2014}
}
|
| Buschmann M, Deutscher NM, Sherlock V, Palm M, Warneke T and Notholt J ({2016}), "Retrieval of xCO(2) from ground-based mid-infrared (NDACC) solar absorption spectra and comparison to TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({2}), pp. 577-585. |
| Abstract: High-resolution solar absorption spectra, taken within the Network for the Detection of Atmospheric Composition Change Infrared Working Group (NDACC-IRWG) in the mid-infrared spectral region, are used to infer partial or total column abundances of many gases. In this paper we present the retrieval of a column-averaged mole fraction of carbon dioxide from NDACC-IRWG spectra taken with a Fourier transform infrared (FTIR) spectrometer at the site in Ny-Alesund, Spitsbergen. The retrieved time series is compared to colocated standard TCCON (Total Carbon Column Observing Network) measurements of column-averaged dry-air mole fractions of CO2 (denoted by xCO(2)). Comparing the NDACC and TCCON retrievals, we find that the sensitivity of the NDACC retrieval is lower in the troposphere (by a factor of 2) and higher in the stratosphere, compared to TCCON. Thus, the NDACC retrieval is less sensitive to tropospheric changes (e.g., the seasonal cycle) in the column average. |
BibTeX:
@article{buschmann16a,
author = {Buschmann, Matthias and Deutscher, Nicholas M. and Sherlock, Vanessa and Palm, Mathias and Warneke, Thorsten and Notholt, Justus},
title = {Retrieval of xCO(2) from ground-based mid-infrared (NDACC) solar absorption spectra and comparison to TCCON},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2016},
volume = {9},
number = {2},
pages = {577--585},
doi = {10.5194/amt-9-577-2016}
}
|
| Butler MP, Davis KJ, Denning AS and Kawa SR ({2010}), "Using continental observations in global atmospheric inversions of CO2: North American carbon sources and sinks", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 550-572. |
| Abstract: We evaluate North American carbon fluxes using a monthly global Bayesian synthesis inversion that includes well-calibrated carbon dioxide concentrations measured at continental flux towers. We employ the NASA Parametrized Chemistry Tracer Model (PCTM) for atmospheric transport and a TransCom-style inversion with subcontinental resolution. We subsample carbon dioxide time series at four North American flux tower sites for mid-day hours to ensure sampling of a deep, well-mixed atmospheric boundary layer. The addition of these flux tower sites to a global network reduces North America mean annual flux uncertainty for 2001-2003 by 20% to 0.4 Pg C yr-1 compared to a network without the tower sites. North American flux is estimated to be a net sink of 1.2 +/- 0.4 Pg C yr-1 which is within the uncertainty bounds of the result without the towers. Uncertainty reduction is found to be local to the regions within North America where the flux towers are located, and including the towers reduces covariances between regions within North America. Mid-day carbon dioxide observations from flux towers provide a viable means of increasing continental observation density and reducing the uncertainty of regional carbon flux estimates in atmospheric inversions. |
BibTeX:
@article{butler10a,
author = {Butler, M. P. and Davis, K. J. and Denning, A. S. and Kawa, S. R.},
title = {Using continental observations in global atmospheric inversions of CO2: North American carbon sources and sinks},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2010},
volume = {62},
number = {5, SI},
pages = {550--572},
doi = {10.1111/j.1600-0889.2010.00501.x}
}
|
| Butz A, Hasekamp OP, Frankenberg C, Vidot J and Aben I ({2010}), "CH4 retrievals from space-based solar backscatter measurements: Performance evaluation against simulated aerosol and cirrus loaded scenes", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 16, {2010}. Vol. {115} |
| Abstract: Monitoring of atmospheric methane (CH4) concentrations from space-based instruments such as the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and the Greenhouse Gases Observing Satellite (GOSAT) relies on observations of sunlight backscattered to space by the Earth's surface and atmosphere. Retrieval biases occur due to unaccounted scattering effects by aerosols and thin cirrus that modify the lightpath. Here, we evaluate the accuracy of two retrieval methods that aim at minimizing such scattering induced errors. The lightpath ``proxy'' method, applicable to SCIAMACHY and GOSAT, retrieves CH4 and carbon dioxide (CO2) simultaneously and uses CO2 as a proxy for lightpath modification. The ``physics-based'' method, which we propose for GOSAT, aims at simultaneously retrieving CH4 concentrations and scattering properties of the atmosphere. We evaluate performance of the methods against a trial ensemble of simulated aerosol and cirrus loaded scenes. More than 80% of the trials yield residual scattering induced CH4 errors below 0.6% and 0.8% for the proxy and the physics-based approach, respectively. Very few cases result in errors greater than 2% for both methods. Advantages of the proxy approach are efficient and robust performance yielding more useful retrievals than the physics-based method which reveals some nonconvergent cases. The major disadvantage of the proxy method is the uncertainty of the proxy CO2 concentration contributing to the overall error budget. Residual errors generally correlate with particle and surface properties and thus might impact inverse modeling of CH4 sources and sinks. |
BibTeX:
@article{butz10a,
author = {Butz, A. and Hasekamp, O. P. and Frankenberg, C. and Vidot, J. and Aben, I.},
title = {CH4 retrievals from space-based solar backscatter measurements: Performance evaluation against simulated aerosol and cirrus loaded scenes},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2010},
volume = {115},
doi = {10.1029/2010JD014514}
}
|
| Butz A, Guerlet S, Hasekamp O, Schepers D, Galli A, Aben I, Frankenberg C, Hartmann JM, Tran H, Kuze A, Keppel-Aleks G, Toon G, Wunch D, Wennberg P, Deutscher N, Griffith D, Macatangay R, Messerschmidt J, Notholt J and Warneke T ({2011}), "Toward accurate CO2 and CH4 observations from GOSAT", GEOPHYSICAL RESEARCH LETTERS., JUL 30, {2011}. Vol. {38} |
| Abstract: The column-average dry air mole fractions of atmospheric carbon dioxide and methane (X-CO2 and X-CH4) are inferred from observations of backscattered sunlight conducted by the Greenhouse gases Observing SATellite (GOSAT). Comparing the first year of GOSAT retrievals over land with colocated ground-based observations of the Total Carbon Column Observing Network (TCCON), we find an average difference (bias) of -0.05% and -0.30% for X-CO2 and X-CH4 with a station-to-station variability (standard deviation of the bias) of 0.37% and 0.26% among the 6 considered TCCON sites. The root-mean square deviation of the bias-corrected satellite retrievals from colocated TCCON observations amounts to 2.8 ppm for X-CO2 and 0.015 ppm for X-CH4. Without any data averaging, the GOSAT records reproduce general source/sink patterns such as the seasonal cycle of X-CO2 suggesting the use of the satellite retrievals for constraining surface fluxes. Citation: Butz, A., et al. (2011), Toward accurate CO2 and CH4 observations from GOSAT, Geophys. Res. Lett., 38, L14812, doi:10.1029/2011GL047888. |
BibTeX:
@article{butz11a,
author = {Butz, A. and Guerlet, S. and Hasekamp, O. and Schepers, D. and Galli, A. and Aben, I. and Frankenberg, C. and Hartmann, J. -M. and Tran, H. and Kuze, A. and Keppel-Aleks, G. and Toon, G. and Wunch, D. and Wennberg, P. and Deutscher, N. and Griffith, D. and Macatangay, R. and Messerschmidt, J. and Notholt, J. and Warneke, T.},
title = {Toward accurate CO2 and CH4 observations from GOSAT},
journal = {GEOPHYSICAL RESEARCH LETTERS},
year = {2011},
volume = {38},
doi = {10.1029/2011GL047888}
}
|
| Butz A, Guerlet S, Hasekamp OP, Kuze A and Suto H ({2013}), "Using ocean-glint scattered sunlight as a diagnostic tool for satellite remote sensing of greenhouse gases", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {6}({9}), pp. 2509-2520. |
| Abstract: Spectroscopic measurements of sunlight backscattered by the Earth's surface is a technique widely used for remote sensing of atmospheric constituent concentrations from space. Thereby, remote sensing of greenhouse gases poses particularly challenging accuracy requirements for instrumentation and retrieval algorithms which, in general, suffer from various error sources. Here, we investigate a method that helps disentangle sources of error for observations of sunlight backscattered from the glint spot on the ocean surface. The method exploits the backscattering characteristics of the ocean surface, which is bright for glint geometry but dark for off-glint angles. This property allows for identifying a set of clean scenes where light scattering due to particles in the atmosphere is negligible such that uncertain knowledge of the lightpath can be excluded as a source of error. We apply the method to more than 3 yr of ocean-glint measurements by the Thermal And Near infrared Sensor for carbon Observation (TANSO) Fourier Transform Spectrometer (FTS) onboard the Greenhouse Gases Observing Satellite (GOSAT), which aims at measuring carbon dioxide (CO2) and methane (CH4) concentrations. The proposed method is able to clearly monitor recent improvements in the instrument calibration of the oxygen (O-2) A-band channel and suggests some residual uncertainty in our knowledge about the instrument. We further assess the consistency of CO2 retrievals from several absorption bands between 6400 cm(-1) (1565 nm) and 4800 cm(-1) (2100 nm) and find that the absorption bands commonly used for monitoring of CO2 dry air mole fractions from GOSAT allow for consistency better than 1.5 ppm. Usage of other bands reveals significant inconsistency among retrieved CO2 concentrations pointing at inconsistency of spectroscopic parameters. |
BibTeX:
@article{butz13a,
author = {Butz, A. and Guerlet, S. and Hasekamp, O. P. and Kuze, A. and Suto, H.},
title = {Using ocean-glint scattered sunlight as a diagnostic tool for satellite remote sensing of greenhouse gases},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2013},
volume = {6},
number = {9},
pages = {2509--2520},
doi = {10.5194/amt-6-2509-2013}
}
|
| Butz A, Orphal J, Checa-Garcia R, Friedl-Vallon F, von Clarmann T, Bovensmann H, Hasekamp O, Landgraf J, Knigge T, Weise D, Sqalli-Houssini O and Kemper D ({2015}), "Geostationary Emission Explorer for Europe (G3E): mission concept and initial performance assessment", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({11}), pp. 4719-4734. |
| Abstract: The Geostationary Emission Explorer for Europe (G3E) is a concept for a geostationary satellite sounder that aims to constrain the sources and sinks of greenhouse gases carbon dioxide (CO2) and methane (CH4) for continental-scale regions. Its primary focus is on central Europe. G3E carries a spectrometer system that collects sunlight backscattered from the Earth's surface and atmosphere in the near-infrared (NIR) and shortwave-infrared (SWIR) spectral range. Solar absorption spectra allow for spatiotemporally dense observations of the column-average concentrations of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO). The mission concept in particular facilitates sampling of the diurnal variation with several measurements per day during summer. Here, we present the mission concept and carry out an initial performance assessment of the retrieval capabilities. The radiometric performance of the 4 grating spectrometers is tuned to reconcile small ground-pixel sizes (similar to 2 km x 3 km at 50 degrees latitude) with short single-shot exposures (similar to 2.9 s) that allow for sampling continental regions such as central Europe within 2 h while providing a sufficient signal-to-noise ratio. The noise errors to be expected for XCO2, XCH4, and XCO are assessed through retrieval simulations for a European trial ensemble. Generally, single-shot precision for the targeted XCO2 and XCH4 is better than 0.5% with some exception for scenes with low infrared surface albedo observed under low sun conditions in winter. For XCO, precision is generally better than 10 br> Performance for aerosol and cirrus loaded atmospheres is assessed by mimicking G3E's slant view on Europe for an ensemble of atmospheric scattering properties used previously for evaluating nadir-viewing low-Earth-orbit (LEO) satellites. While retrieval concepts developed for LEO configurations generally succeed in mitigating aerosol- and cirrus-induced retrieval errors for G3E's setup, residual errors are somewhat greater in geostationary orbit (GEO) than in LEO. G3E's deployment in the vicinity of the Meteosat Third Generation (MTG) satellites has the potential to make synergistic use of MTG's sounding capabilities e.g. with respect to characterization of aerosol and cloud properties or with respect to enhancing carbon monoxide retrievals by combining G3E's solar and MTG's thermal infrared spectra. |
BibTeX:
@article{butz15a,
author = {Butz, A. and Orphal, J. and Checa-Garcia, R. and Friedl-Vallon, F. and von Clarmann, T. and Bovensmann, H. and Hasekamp, O. and Landgraf, J. and Knigge, T. and Weise, D. and Sqalli-Houssini, O. and Kemper, D.},
title = {Geostationary Emission Explorer for Europe (G3E): mission concept and initial performance assessment},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2015},
volume = {8},
number = {11},
pages = {4719--4734},
doi = {10.5194/amt-8-4719-2015}
}
|
| Byrne B, Jones DBA, Strong K, Zeng ZC, Deng F and Liu J ({2017}), "Sensitivity of CO2 surface flux constraints to observational coverage", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUN 27, {2017}. Vol. {122}({12}), pp. 6672-6694. |
| Abstract: Inverse modeling of regional CO2 fluxes using atmospheric CO2 data is sensitive to the observational coverage of the observing network. Here we use the GEOS-Chem adjoint model to examine the sensitivity to CO2 fluxes of observations from the in situ surface network, the Total Carbon Column Observing Network (TCCON), the Greenhouse Gases Observing Satellite (GOSAT), and the Orbiting Carbon Observatory (OCO-2). We find that OCO-2 has high sensitivity to fluxes throughout the tropics and Southern Hemisphere, while surface observations have high sensitivity to fluxes in the northern extratropics throughout the year. For GOSAT viewing modes, ocean glint data provide the strongest constraints on fluxes in the tropics and Southern Hemisphere during Northern Hemisphere fall and winter relative to other viewing modes. In contrast, GOSAT nadir land data offer the greater sensitivity to fluxes in these regions during Northern Hemisphere spring and summer. For OCO-2 viewing modes, ocean glint data provided the dominant sensitivity to the surface fluxes in the northern subtropics, tropics, and Southern Hemisphere. We performed a series of inversion analyses using pseudodata and found that the varying sensitivities can result in large differences in regional flux estimates. However, combining measurements from different observing systems to exploit their complementarity may lead to a posteriori flux estimates with improved accuracy. |
BibTeX:
@article{byrne17a,
author = {Byrne, B. and Jones, D. B. A. and Strong, K. and Zeng, Z. -C. and Deng, F. and Liu, J.},
title = {Sensitivity of CO2 surface flux constraints to observational coverage},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2017},
volume = {122},
number = {12},
pages = {6672--6694},
doi = {10.1002/2016JD026164}
}
|
| Byrne B, Wunch D, Jones DBA, Strong K, Deng F, Baker I, Kohler P, Frankenberg C, Joiner J, Arora VK, Badawy B, Harper AB, Warneke T, Petri C, Kivi R and Roehl CM ({2018}), "Evaluating GPP and Respiration Estimates Over Northern Midlatitude Ecosystems Using Solar-Induced Fluorescence and Atmospheric CO2 Measurements", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., SEP, {2018}. Vol. {123}({9}), pp. {2976-2997}. |
| Abstract: On regional to global scales, few constraints exist on gross primary productivity (GPP) and ecosystem respiration (R-e) fluxes. Yet constraints on these fluxes are critical for evaluating and improving terrestrial biosphere models. In this study, we evaluate the seasonal cycle of GPP, R-e, and net ecosystem exchange (NEE) produced by four terrestrial biosphere models and FLUXCOM, a data-driven model, over northern midlatitude ecosystems. We evaluate the seasonal cycle of GPP and NEE using solar-induced fluorescence retrieved from the Global Ozone Monitoring Experiment-2 and column-averaged dry-air mole fractions of CO2 (X-CO2) from the Total Carbon Column Observing Network, respectively. We then infer R-e by combining constraints on GPP with constraints on NEE from two flux inversions. An ensemble of optimized R-e seasonal cycles is generated using five GPP estimates and two NEE estimates. The optimized R-e curves generally show high consistency with each other, with the largest differences due to the magnitude of GPP. We find optimized R-e exhibits a systematically broader summer maximum than modeled R-e, with values lower during June-July and higher during the fall than R-e. Further analysis suggests that the differences could be due to seasonal variations in the carbon use efficiency (possibly due to an ecosystem-scale Kok effect) and to seasonal variations in the leaf litter and fine root carbon pool. The results suggest that the inclusion of variable carbon use efficiency for autotrophic respiration and carbon pool dependence for heterotrophic respiration is important for accurately simulating R-e. |
BibTeX:
@article{byrne18a,
author = {Byrne, B. and Wunch, D. and Jones, D. B. A. and Strong, K. and Deng, F. and Baker, I. and Kohler, P. and Frankenberg, C. and Joiner, J. and Arora, V. K. and Badawy, B. and Harper, A. B. and Warneke, T. and Petri, C. and Kivi, R. and Roehl, C. M.},
title = {Evaluating GPP and Respiration Estimates Over Northern Midlatitude Ecosystems Using Solar-Induced Fluorescence and Atmospheric CO2 Measurements},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2018},
volume = {123},
number = {9},
pages = {2976-2997},
doi = {{10.1029/2018JG004472}}
}
|
| Carels N ({2011}), "The Challenge of Bioenergies: An Overview", In BIOFUEL'S ENGINEERING PROCESS TECHNOLOGY. , pp. 23-64. InTech.
[BibTeX] |
BibTeX:
@incollection{carels11a,
author = {Carels, Nicolas},
editor = {Bernardes, MAD},
title = {The Challenge of Bioenergies: An Overview},
booktitle = {BIOFUEL'S ENGINEERING PROCESS TECHNOLOGY},
publisher = {InTech},
year = {2011},
pages = {23--64}
}
|
| Carouge C, Rayner PJ, Peylin P, Bousquet P, Chevallier F and Ciais P ({2010}), "What can we learn from European continuous atmospheric CO2 measurements to quantify regional fluxes - Part 2: Sensitivity of flux accuracy to inverse setup", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({6}), pp. 3119-3129. |
| Abstract: An inverse model using atmospheric CO2 observations from a European network of stations to reconstruct daily CO2 fluxes and their uncertainties over Europe at 50 km resolution has been developed within a Bayesian framework. We use the pseudo-data approach in which we try to recover known fluxes using a range of perturbations to the input. In this study, the focus is put on the sensitivity of flux accuracy to the inverse setup, varying the prior flux errors, the pseudo-data errors and the network of stations. We show that, under a range of assumptions about prior error and data error we can recover fluxes reliably at the scale of 1000 km and 10 days. At smaller scales the performance is highly sensitive to details of the inverse set-up. The use of temporal correlations in the flux domain appears to be of the same importance as the spatial correlations. We also note that the use of simple, isotropic correlations on the prior flux errors is more reliable than the use of apparently physically-based errors. Finally, increasing the European atmospheric network density improves the area with significant error reduction in the flux retrieval. |
BibTeX:
@article{carouge10a,
author = {Carouge, C. and Rayner, P. J. and Peylin, P. and Bousquet, P. and Chevallier, F. and Ciais, P.},
title = {What can we learn from European continuous atmospheric CO2 measurements to quantify regional fluxes - Part 2: Sensitivity of flux accuracy to inverse setup},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2010},
volume = {10},
number = {6},
pages = {3119--3129},
doi = {10.5194/acp-10-3119-2010}
}
|
| Cervarich M, Shu S, Jain AK, Arneth A, Canadell J, Friedlingstein P, Houghton RA, Kato E, Koven C, Patra P, Poulter B, Sitch S, Stocker B, Viovy N, Wiltshire A and Zeng N ({2016}), "The terrestrial carbon budget of South and Southeast Asia", ENVIRONMENTAL RESEARCH LETTERS., OCT, {2016}. Vol. {11}({10}) |
| Abstract: Accomplishing the objective of the current climate policies will require establishing carbon budget and flux estimates in each region and county of the globe by comparing and reconciling multiple estimates including the observations and the results of top-down atmospheric carbon dioxide (CO2) inversions and bottom-up dynamic global vegetation models. With this in view, this study synthesizes the carbon source/sink due to net ecosystem productivity (NEP), land cover land use change (E-LUC), fires and fossil burning (E-FIRE) for the South Asia (SA), Southeast Asia (SEA) and South and Southeast Asia (SSEA = SA + SEA) and each country in these regions using the multiple top-down and bottom-up modeling results. The terrestrial net biome productivity (NBP = NEP - E-LUC - E-FIRE) calculated based on bottom-up models in combination with E-FIRE based on GFED4s data show net carbon sinks of 217 +/- 147, 10 +/- 55, and 227 +/- 279 TgC yr(-1) for SA, SEA, and SSEA. The top-down models estimated NBP net carbon sinks were 20 +/- 170, 4 +/- 90 and 24 +/- 180 TgC yr(-1). In comparison, regional emissions from the combustion of fossil fuels were 495, 275, and 770 TgC yr(-1), which are many times higher than the NBP sink estimates, suggesting that the contribution of the fossil fuel emissions to the carbon budget of SSEA results in a significant net carbon source during the 2000s. When considering both NBP and fossil fuel emissions for the individual countries within the regions, Bhutan and Laos were net carbon sinks and rest of the countries were net carbon source during the 2000s. The relative contributions of each of the fluxes (NBP, NEP, ELUC, and EFIRE, fossil fuel emissions) to a nation's net carbon flux varied greatly from country to country, suggesting a heterogeneous dominant carbon fluxes on the country-level throughout SSEA. |
BibTeX:
@article{cervarich16a,
author = {Cervarich, Matthew and Shu, Shijie and Jain, Atul K. and Arneth, Almut and Canadell, Josep and Friedlingstein, Pierre and Houghton, Richard A. and Kato, Etsushi and Koven, Charles and Patra, Prabir and Poulter, Ben and Sitch, Stephen and Stocker, Beni and Viovy, Nicolas and Wiltshire, Andy and Zeng, Ning},
title = {The terrestrial carbon budget of South and Southeast Asia},
journal = {ENVIRONMENTAL RESEARCH LETTERS},
year = {2016},
volume = {11},
number = {10},
doi = {10.1088/1748-9326/11/10/105006}
}
|
| Chatterjee A, Michalak AM, Anderson JL, Mueller KL and Yadav V ({2012}), "Toward reliable ensemble Kalman filter estimates of CO2 fluxes", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 28, {2012}. Vol. {117} |
| Abstract: The use of ensemble filters for estimating sources and sinks of carbon dioxide (CO2) is becoming increasingly common, because they provide a relatively computationally efficient framework for assimilating high-density observations of CO2. Their applicability for estimating fluxes at high-resolutions and the equivalence of their estimates to those from more traditional ``batch'' inversion methods have not been demonstrated, however. In this study, we introduce a Geostatistical Ensemble Square Root Filter (GEnSRF) as a prototypical filter and examine its performance using a synthetic data study over North America at a high spatial (1 degrees x 1 degrees) and temporal (3-hourly) resolution. The ensemble performance, both in terms of estimates and associated uncertainties, is benchmarked against a batch inverse modeling setup in order to isolate and quantify the degradation in the estimates due to the numerical approximations and parameter choices in the ensemble filter. The examined case studies demonstrate that adopting state-of-the-art covariance inflation and localization schemes is a necessary but not sufficient condition for ensuring good filter performance, as defined by its ability to yield reliable flux estimates and uncertainties across a range of resolutions. Observational density is found to be another critical factor for stabilizing the ensemble performance, which is attributed to the lack of a dynamical model for evolving the ensemble between assimilation times. This and other results point to key differences between the applicability of ensemble approaches to carbon cycle science relative to its use in meteorological applications where these tools were originally developed. |
BibTeX:
@article{chatterjee12a,
author = {Chatterjee, Abhishek and Michalak, Anna M. and Anderson, Jeffrey L. and Mueller, Kim L. and Yadav, Vineet},
title = {Toward reliable ensemble Kalman filter estimates of CO2 fluxes},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2012},
volume = {117},
doi = {10.1029/2012JD018176}
}
|
| Chatterjee A (2012), "Data Assimilation for Atmospheric CO2: Towards Improved Estimates of CO2 Concentrations and Fluxes.". Thesis at: University of Michigan. |
BibTeX:
@phdthesis{chatterjee12b,
author = {A Chatterjee},
title = {Data Assimilation for Atmospheric CO2: Towards Improved Estimates of CO2 Concentrations and Fluxes.},
school = {University of Michigan},
year = {2012},
url = {https://deepblue.lib.umich.edu/handle/2027.42/96172}
}
|
| Checa-Garcia R, Landgraf J, Galli A, Hase F, Velazco VA, Tran H, Boudon V, Alkemade F and Butz A ({2015}), "Mapping spectroscopic uncertainties into prospective methane retrieval errors from Sentinel-5 and its precursor", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({9}), pp. 3617-3629. |
| Abstract: Sentinel-5 (S5) and its precursor (S5P) are future European satellite missions aiming at global monitoring of methane (CH4) column-average dry air mole fractions (XCH4). The spectrometers to be deployed onboard the satellites record spectra of sunlight backscattered from the Earth's surface and atmosphere. In particular, they exploit CH4 absorption in the shortwave infrared spectral range around 1.65 mu m (S5 only) and 2.35 mu m (both S5 and S5P) wavelength. Given an accuracy goal of better than 2% for XCH4 to be delivered on regional scales, assessment and reduction of potential sources of systematic error such as spectroscopic uncertainties is crucial. Here, we investigate how spectroscopic errors propagate into retrieval errors on the global scale. To this end, absorption spectra of a ground-based Fourier transform spectrometer (FTS) operating at very high spectral resolution serve as estimate for the quality of the spectroscopic parameters. Feeding the FTS fitting residuals as a perturbation into a global ensemble of simulated S5- and S5P-like spectra at relatively low spectral resolution, XCH4 retrieval errors exceed 0.6% in large parts of the world and show systematic correlations on regional scales, calling for improved spectroscopic parameters. |
BibTeX:
@article{checa-garcia15a,
author = {Checa-Garcia, R. and Landgraf, J. and Galli, A. and Hase, F. and Velazco, V. A. and Tran, H. and Boudon, V. and Alkemade, F. and Butz, A.},
title = {Mapping spectroscopic uncertainties into prospective methane retrieval errors from Sentinel-5 and its precursor},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2015},
volume = {8},
number = {9},
pages = {3617--3629},
doi = {10.5194/amt-8-3617-2015}
}
|
| Chen B and Coops NC ({2009}), "Understanding of Coupled Terrestrial Carbon, Nitrogen and Water Dynamics-An Overview", SENSORS., NOV, {2009}. Vol. {9}({11}), pp. 8624-8657. |
| Abstract: Coupled terrestrial carbon (C), nitrogen (N) and hydrological processes play a crucial role in the climate system, providing both positive and negative feedbacks to climate change. In this review we summarize published research results to gain an increased understanding of the dynamics between vegetation and atmosphere processes. A variety of methods, including monitoring (e. g., eddy covariance flux tower, remote sensing, etc.) and modeling (i.e., ecosystem, hydrology and atmospheric inversion modeling) the terrestrial carbon and water budgeting, are evaluated and compared. We highlight two major research areas where additional research could be focused: (i) Conceptually, the hydrological and biogeochemical processes are closely linked, however, the coupling processes between terrestrial C, N and hydrological processes are far from well understood; and (ii) there are significant uncertainties in estimates of the components of the C balance, especially at landscape and regional scales. To address these two questions, a synthetic research framework is needed which includes both bottom-up and top-down approaches integrating scalable (footprint and ecosystem) models and a spatially nested hierarchy of observations which include multispectral remote sensing, inventories, existing regional clusters of eddy-covariance flux towers and CO2 mixing ratio towers and chambers. |
BibTeX:
@article{chen09a,
author = {Chen, Baozhang and Coops, Nicholas C.},
title = {Understanding of Coupled Terrestrial Carbon, Nitrogen and Water Dynamics-An Overview},
journal = {SENSORS},
year = {2009},
volume = {9},
number = {11},
pages = {8624--8657},
doi = {10.3390/s91108624}
}
|
| Chen H, Winderlich J, Gerbig C, Katrynski K, Jordan A and Heimann M ({2012}), "Validation of routine continuous airborne CO2 observations near the Bialystok Tall Tower", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({4}), pp. 873-889. |
| Abstract: Since 2002 in situ airborne measurements of atmospheric CO2 mixing ratios have been performed regularly aboard a rental aircraft near Bialystok (53A degrees 08A ` N, 23A degrees 09A ` E), a city in northeastern Poland. Since August 2008, the in situ CO2 measurements have been made by a modified commercially available and fully automated non-dispersive infrared (NDIR) analyzer system. The response of the analyzer has been characterized and the CO2 mixing ratio stability of the associated calibration system has been fully tested, which results in an optimal calibration strategy and allows for an accuracy of the CO2 measurements within 0.2 ppm. Besides the in situ measurements, air samples have been collected in glass flasks and analyzed in the laboratory for CO2 and other trace gases. To validate the in situ CO2 measurements against reliable discrete flask measurements, we developed weighting functions that mimic the temporal averaging of the flask sampling process. Comparisons between in situ and flask CO2 measurements demonstrate that these weighting functions can compensate for atmospheric variability, and provide an effective method for validating airborne in situ CO2 measurements. In addition, we show the nine-year records of flask CO2 measurements. The new system, automated since August 2008, has eliminated the need for manual in-flight calibrations, and thus enables an additional vertical profile, 20 km away, to be sampled at no additional cost in terms of flight hours. This sampling strategy provides an opportunity to investigate both temporal and spatial variability on a regular basis. |
BibTeX:
@article{chen12a,
author = {Chen, H. and Winderlich, J. and Gerbig, C. and Katrynski, K. and Jordan, A. and Heimann, M.},
title = {Validation of routine continuous airborne CO2 observations near the Bialystok Tall Tower},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2012},
volume = {5},
number = {4},
pages = {873--889},
doi = {10.5194/amt-5-873-2012}
}
|
| Chen B (2012), "Towards an understanding of coupled carbon, water and nitrogen dynamics at sand, landscape and regional scales". Thesis at: THE UNIVERSITY OF BRITISH COLUMBIA. |
BibTeX:
@phdthesis{chen12b,
author = {B Chen},
title = {Towards an understanding of coupled carbon, water and nitrogen dynamics at sand, landscape and regional scales},
school = {THE UNIVERSITY OF BRITISH COLUMBIA},
year = {2012},
url = {https://open.library.ubc.ca/collections/ubctheses/24/items/1.0103459}
}
|
| Chen B, Zhang H, Coops NC, Fu D, Worthy DEJ, Xu G and Black TA ({2014}), "Assessing scalar concentration footprint climatology and land surface impacts on tall-tower CO2 concentration measurements in the boreal forest of central Saskatchewan, Canada", THEORETICAL AND APPLIED CLIMATOLOGY., OCT, {2014}. Vol. {118}({1-2}), pp. 115-132. |
| Abstract: Reducing the large uncertainties in current estimates of CO2 sources and sinks at regional scales (10(2)-10(5) km(2)) is fundamental to improving our understanding of the terrestrial carbon cycle. Continuous high-precision CO2 concentration measurements on a tower within the planetary boundary layer contain information on regional carbon fluxes; however, its spatial representativeness is generally unknown. In this study, we developed a footprint model (Simple Analytical Footprint model based on Eulerian coordinates for scalar Concentration [SAFE-C]) and applied it to two CO2 concentration towers in central Canada: the East Trout Lake 106-m-tall tower (54A degrees 21'N, 104A degrees 59'W) and the Candle Lake 28-m-high tower (53A degrees 59'N, 105A degrees 07'W). Results show that the ETL tower's annual concentration footprints were around 10(3)-10(5) km(2). The monthly footprint climatologies in summer were 1.5-2 times larger than in winter. The impacts of land surface carbon flux associated with heterogeneous distribution of vegetation types on the CO2 concentration measurements were different for the different heights, varied with a range of +/- 5 % to +/- 10 % among four heights. This study indicates that concentration footprint climatology analysis is important in interpreting the seasonal, annual and inter-annual variations of tower measured CO2 concentration data and is essential for comparing and scaling regional carbon flux estimates using top-down or bottom-up approaches. |
BibTeX:
@article{chen14a,
author = {Chen, Baozhang and Zhang, Huifang and Coops, Nicholas C. and Fu, Dongjie and Worthy, Douglas E. J. and Xu, Guang and Black, T. Andy},
title = {Assessing scalar concentration footprint climatology and land surface impacts on tall-tower CO2 concentration measurements in the boreal forest of central Saskatchewan, Canada},
journal = {THEORETICAL AND APPLIED CLIMATOLOGY},
year = {2014},
volume = {118},
number = {1-2},
pages = {115--132},
doi = {10.1007/s00704-013-1038-2}
}
|
| Chen JM, Fung JW, Mo G, Deng F and West TO ({2015}), "Atmospheric inversion of surface carbon flux with consideration of the spatial distribution of US crop production and consumption", BIOGEOSCIENCES. Vol. {12}({2}), pp. 323-343. |
| Abstract: In order to improve quantification of the spatial distribution of carbon sinks and sources in the conterminous US, we conduct a nested global atmospheric inversion with detailed spatial information on crop production and consumption. County-level cropland net primary productivity, harvested biomass, soil carbon change, and human and livestock consumption data over the conterminous US are used for this purpose. Time-dependent Bayesian synthesis inversions are conducted based on CO2 observations at 210 stations to infer CO2 fluxes globally at monthly time steps with a nested focus on 30 regions in North America. Prior land surface carbon fluxes are first generated using a bio-spheric model, and the inversions are constrained using prior fluxes with and without adjustments for crop production and consumption over the 2002-2007 period. After these adjustments, the inverted regional carbon sink in the US Midwest increases from 0.25 +/- 0.03 to 0.42 +/- 0.13 PgC yr(-1), whereas the large sink in the US southeast forest region is weakened from 0.41 +/- 0.12 to 0.29 +/- 0.12 PgC yr(-1). These adjustments also reduce the inverted sink in the west region from 0.066 +/- 0.04 to 0.040 +/- 0.02 PgC yr(-1) because of high crop consumption and respiration by humans and livestock. The general pattern of sink increases in crop production areas and sink decreases (or source increases) in crop consumption areas highlights the importance of considering the lateral carbon transfer in crop products in atmospheric inverse modeling, which provides a reliable atmospheric perspective of the overall carbon balance at the continental scale but is unreliable for separating fluxes from different ecosystems. |
BibTeX:
@article{chen15a,
author = {Chen, J. M. and Fung, J. W. and Mo, G. and Deng, F. and West, T. O.},
title = {Atmospheric inversion of surface carbon flux with consideration of the spatial distribution of US crop production and consumption},
journal = {BIOGEOSCIENCES},
year = {2015},
volume = {12},
number = {2},
pages = {323--343},
doi = {10.5194/bg-12-323-2015}
}
|
| Chen M (2016), "Evaluation and Application of the Community Land Model for Simulating Energy and Carbon Exchange in Agricultural Ecosystems". Thesis at: UNIVERSITY OF MINNESOTA. |
BibTeX:
@phdthesis{chen16a,
author = {M Chen},
title = {Evaluation and Application of the Community Land Model for Simulating Energy and Carbon Exchange in Agricultural Ecosystems},
school = {UNIVERSITY OF MINNESOTA},
year = {2016},
url = {http://search.proquest.com/openview/4e5113263c4ca244a5b38a8271693056/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Chen Z, Chen JM, Zhang S, Zheng X, Ju W, Mo G and Lu X (2016), "Optimization of terrestrial ecosystem model parameters using atmospheric CO2 concentration data with the Global Carbon Assimilation System (GCAS)", Journal of Geophysical Research: Biogeosciences. Vol. 122(12), pp. 3218-3237. Wiley Online Library. |
BibTeX:
@article{chen16b,
author = {Chen, Zhuoqi and Chen, Jing M and Zhang, Shupeng and Zheng, Xiaogu and Ju, Weiming and Mo, Gang and Lu, Xiaoliang},
title = {Optimization of terrestrial ecosystem model parameters using atmospheric CO2 concentration data with the Global Carbon Assimilation System (GCAS)},
journal = {Journal of Geophysical Research: Biogeosciences},
publisher = {Wiley Online Library},
year = {2016},
volume = {122},
number = {12},
pages = {3218--3237},
doi = {10.1002/2016JG003716/full}
}
|
| Chen JM, Mo G and Deng F ({2017}), "A joint global carbon inversion system using both CO2 and (CO2)-C-13 atmospheric concentration data", GEOSCIENTIFIC MODEL DEVELOPMENT., MAR 16, {2017}. Vol. {10}({3}), pp. 1131-1156. |
| Abstract: Observations of (CO2)-C-13 at 73 sites compiled in the GLOBALVIEW database are used for an additional constraint in a global atmospheric inversion of the surface CO2 flux using CO2 observations at 210 sites (62 collocated with (CO2)-C-13 sites) for the 2002-2004 period for 39 land regions and 11 ocean regions. This constraint is implemented using prior CO2 fluxes estimated with a terrestrial ecosystem model and an ocean model. These models simulate (CO2)-C-13 discrimination rates of terrestrial photosynthesis and oceanatmosphere diffusion processes. In both models, the (CO2)-C-13 disequilibrium between fluxes to and from the atmosphere is considered due to the historical change in atmospheric (CO2)-C-13 concentration. This joint inversion system using both(13)CO(2) and CO2 observations is effectively a double deconvolution system with consideration of the spatial variations of isotopic discrimination and disequilibrium. Compared to the CO2-only inversion, this (CO2)-C-13 constraint on the inversion considerably reduces the total land carbon sink from 3.40 +/- 0.84 to 2.53 +/- 0.93 Pg Cyear 1 but increases the total oceanic carbon sink from 1.48 +/- 0.40 to 2.36 +/- 0.49 Pg C year 1. This constraint also changes the spatial distribution of the carbon sink. The largest sink increase occurs in the Amazon, while the largest source increases are in southern Africa, and Asia, where CO2 data are sparse. Through a case study, in which the spatial distribution of the annual (CO2)-C-13 discrimination rate over land is ignored by treating it as a constant at the global average of 14 : 1 the spatial distribution of the inverted CO2 flux over land was found to be significantly modified (up to 15% for some regions). The uncertainties in our disequilibrium flux estimation are 8.0 and 12.7 Pg C year 1% for land and ocean, respectively. These uncertainties induced the unpredictability of 0.47 and 0.54 Pg Cyear(-1) in the inverted CO2 fluxes for land and ocean, respectively. Our joint inversion system is therefore useful for improving the partitioning between ocean and land sinks and the spatial distribution of the inverted carbon flux. |
BibTeX:
@article{chen17a,
author = {Chen, Jing M. and Mo, Gang and Deng, Feng},
title = {A joint global carbon inversion system using both CO2 and (CO2)-C-13 atmospheric concentration data},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2017},
volume = {10},
number = {3},
pages = {1131--1156},
doi = {10.5194/gmd-10-1131-2017}
}
|
| Cheng Y, An X, Yun F, Zhou L, Liu L, Fang S and Xu L (2013), "Simulation of CO2 variations at Chinese background atmospheric monitoring stations between 2000 and 2009: Applying a CarbonTracker model", Chin. Sci. Bull. Vol. 58(32), pp. 3986-3993.
[BibTeX] |
BibTeX:
@article{cheng13a,
author = {Cheng, Y and An, X and Yun, F and Zhou, L and Liu, L and Fang, S and Xu, Lin},
title = {Simulation of CO2 variations at Chinese background atmospheric monitoring stations between 2000 and 2009: Applying a CarbonTracker model},
journal = {Chin. Sci. Bull},
year = {2013},
volume = {58},
number = {32},
pages = {3986--3993}
}
|
| Cheng S, An X, Zhou L, Liu L, Fang S, Yao B and Liu Z (2015), "CO2 concentration representation of source and sink area at Shangdianzi atmospheric background station in Beijing", China Environmental Science. |
BibTeX:
@article{cheng15a,
author = {Cheng, Siyang and An, Xingqin and Zhou, Lingxi and Liu, LiXin and Fang, Shuangxi and Yao, Bo and Liu, Zhao},
title = {CO2 concentration representation of source and sink area at Shangdianzi atmospheric background station in Beijing},
journal = {China Environmental Science},
year = {2015},
url = {http://or.nsfc.gov.cn/bitstream/00001903-5/261235/1/1000014841151.pdf}
}
|
| Cheng S, An X, Zhou L, Tans PP and Jacobson A ({2017}), "Atmospheric CO2 at Waliguan station in China: Transport climatology, temporal patterns and source-sink region representativeness", ATMOSPHERIC ENVIRONMENT., JUN, {2017}. Vol. {159}, pp. 107-116. |
| Abstract: In order to explore where the source and sink have the greatest impact on CO2 background concentration at Waliguan (WLG) station, a statistical method is here proposed to calculate the representative source sink region. The key to this method is to find the best footprint threshold, and the study is carried out in four parts. Firstly, transport climatology, expressed by total monthly footprint, was simulated by FLEX PART on a 7-day time scale. Surface CO2 emissions in Eurasia frequently transported to WLG station. WLG station was mainly influenced by the westerlies in winter and partly controlled by the Southeast Asian monsoon in summer. Secondly, CO2 concentrations, simulated by CT2015, were processed and analyzed through data quality control, screening, fitting and comparing. CO2 concentrations displayed obvious seasonal variation, with the maximum and minimum concentration appearing in April and August, respectively. The correlation of CO2 fitting background concentrations was R-2 = 0.91 between simulation and observation. The temporal patterns were mainly correlated with CO2 exchange of biosphere atmosphere, human activities and air transport. Thirdly, for the monthly CO2 fitting background concentrations from CT2015, a best footprint threshold was found based on correlation analysis and numerical iteration using the data of footprints and emissions. The grid cells where monthly footprints were greater than the best footprint threshold were the best threshold area corresponding to representative source-sink region. The representative source-sink region of maximum CO2 concentration in April was primarily located in Qinghai province, but the minimum CO2 concentration in August was mainly influenced by emissions in a wider region. Finally, we briefly presented the CO2 source-sink characteristics in the best threshold area. Generally, the best threshold area was a carbon sink. The major source and sink were relatively weak owing to less human activities and vegetation types in this high altitude area. CO2 concentrations were more influenced by human activities when air mass passed through many urban areas in summer. Therefore, the combination of footprints and emissions is an effective approach for assessing the source-sink region representativeness of CO2 background concentration. (C) 2017 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{cheng17a,
author = {Cheng, Siyang and An, Xingqin and Zhou, Lingxi and Tans, Pieter P. and Jacobson, Andy},
title = {Atmospheric CO2 at Waliguan station in China: Transport climatology, temporal patterns and source-sink region representativeness},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2017},
volume = {159},
pages = {107--116},
doi = {10.1016/j.atmosenv.2017.03.055}
}
|
| Cheng H, Mi Z, Wei X, Yong-wei W, Wei W, Griffis T, Shou-dong L and Xu-hui L (2017), "Effect of Flux and its Uncertainty on Tall Tower CO2 Concentration Simulation in the Agricultural Domain", 中国农业气象 (Chinese Journal of Agrometeorology). |
BibTeX:
@article{cheng17b,
author = {Hu Cheng and Zhang Mi and Xiao Wei and Wang Yong-wei and Wang Wei and Tim Griffis and Liu Shou-dong and Li Xu-hui},
title = {Effect of Flux and its Uncertainty on Tall Tower CO2 Concentration Simulation in the Agricultural Domain},
journal = {中国农业气象 (Chinese Journal of Agrometeorology)},
year = {2017},
url = {https://yncenter.sites.yale.edu/sites/default/files/files/hu_cheng_2017-2.pdf}
}
|
| Cheng H, Mi Z, Wei X, Yong-wei W, Wei W, Griffis T, Shou-dong L and Xu-hui L (2017), "Tall tower CO2 concentration simulation using the WRF-STILT model", China Environmental Science. Vol. 37(7), pp. 2424-24-37. |
BibTeX:
@article{cheng17c,
author = {Hu Cheng and Zhang Mi and Xiao Wei and Wang Yong-wei and Wang Wei and Tim Griffis and Liu Shou-dong and Li Xu-hui},
title = {Tall tower CO2 concentration simulation using the WRF-STILT model},
journal = {China Environmental Science},
year = {2017},
volume = {37},
number = {7},
pages = {2424-24-37},
url = {http://manu36.magtech.com.cn/Jweb_zghjkx/CN/article/downloadArticleFile.do?attachType=PDF&id=15218}
}
|
| Cheng H, Shoudong L, Chang C, Jingzheng X, Zhengda C, Wengian L, Jiaping X, mi Z, Wei X and Xuhui L (2017), "Simulation of atmospheric CO2 concentration and source apportionment analysis in Nanjing City", Acta Scientiae Circumstantiae., OCT, 2017. Vol. 37(10), pp. 3862-3875. |
BibTeX:
@article{cheng17d,
author = {Hu Cheng and Liu Shoudong and Cao Chang and Xu Jingzheng and Cao Zhengda and Li Wengian and Xu Jiaping and Zhang mi and Xiao Wei and Li Xuhui},
title = {Simulation of atmospheric CO2 concentration and source apportionment analysis in Nanjing City},
journal = {Acta Scientiae Circumstantiae},
year = {2017},
volume = {37},
number = {10},
pages = {3862-3875},
url = {http://html.rhhz.net/hjkxxb/html/20170224004.htm}
}
|
| Cheng S, Zhou L, Tans PP, An X and Liu Y ({2018}), "Comparison of atmospheric CO2 mole fractions and source sink characteristics at four WMO/GAW stations in China", ATMOSPHERIC ENVIRONMENT., MAY, {2018}. Vol. {180}, pp. {216-225}. |
| Abstract: As CO2 is a primary driving factor of climate change, the mole fraction and source-sink characteristics of atmospheric CO2 over China are constantly inferred from multi-source and multi-site data. In this paper, we compared ground-based CO2 measurements with satellite retrievals and investigated the source-sink regional representativeness at China's four WMO/GAW stations. The results indicate that, firstly, atmospheric CO2 mole fractions from ground-based sampling measurement and Greenhouse Gases Observing Satellite (GOSAT) products reveal similar seasonal variation. The seasonal amplitude of the column-averaged CO2 mole fractions is smaller than that of the ground-based CO2 at all stations. The extrema of the seasonal cycle of ground-based and column CO2 mole fractions are basically synchronous except a slight phase delay at Lin'an (LAN) station. For the two-year average, the column CO2 is lower than ground-based CO2, and both of them reveal the lowest CO2 mole fraction at Waliguan (WLG) station. The lowest (similar to 4 ppm) and largest (similar to 8 ppm) differences between the column and ground-based CO2 appear at WLG and Longfengshan (LFS) stations, respectively. The CO2 mole fraction and its difference between GOSAT and ground-based measurement are smaller in summer than in winter. The differences of summer column CO2 among these stations are also much smaller than their ground-based counterparts. In winter, the maximum of ground-based CO2 mole fractions and the greatest difference between the two (ground-based and column) datasets appear at the LFS station. Secondly, the representative areas of the monthly CO2 background mole fractions at each station were found by employing footprints and emissions. Smaller representative areas appeared at Shangdianzi (SDZ) and LFS, whereas larger ones were seen at WLG and LAN. The representative areas in summer are larger than those in winter at WLG and SDZ, but the situation is opposite at LAN and LFS. The representative areas for the stations are different in summer and winter, distributed in four typical regions. The CO2 net fluxes in these representative areas show obvious seasonal cycles with similar trends but different varying ranges and different time of the strongest sink. The intensities and uncertainties of the CO2 fluxes are different at different stations in different months and source-sink sectors. Overall, the WLG station is almost a carbon sink, but the other three stations present stronger carbon sources for most of the year. These findings could be conducive to the application of multi-source CO2 data and the understanding of regional CO2 source-sink characteristics and patterns over China. |
BibTeX:
@article{cheng18a,
author = {Cheng, Siyang and Zhou, Lingxi and Tans, Pieter P. and An, Xingqin and Liu, Yunsong},
title = {Comparison of atmospheric CO2 mole fractions and source sink characteristics at four WMO/GAW stations in China},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2018},
volume = {180},
pages = {216-225},
doi = {{10.1016/j.atmosenv.2018.03.010}}
}
|
| Chevallier F, Engelen RJ, Carouge C, Conway TJ, Peylin P, Pickett-Heaps C, Ramonet M, Rayner PJ and Xueref-Remy I ({2009}), "AIRS-based versus flask-based estimation of carbon surface fluxes", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 23, {2009}. Vol. {114} |
| Abstract: This paper demonstrates an inversion of surface CO2 fluxes using concentrations derived from assimilation of satellite radiances. Radiances come from the Atmospheric Infrared Sounder (AIRS) and are assimilated within the system of the European Centre for Medium-Range Weather Forecasts. We evaluate the quality of the inverted fluxes by comparing simulated concentrations with independent airborne measurements. As a benchmark we use an inversion based on surface flask measurements and another using only the global concentration trend. We show that the AIRS-based inversion is able to improve the match to the independent data compared to the prior estimate but that it usually performs worse than either the flask-based or trend-based inversion. |
BibTeX:
@article{chevallier09a,
author = {Chevallier, Frederic and Engelen, Richard J. and Carouge, Claire and Conway, Thomas J. and Peylin, Philippe and Pickett-Heaps, Christopher and Ramonet, Michel and Rayner, Peter J. and Xueref-Remy, Irene},
title = {AIRS-based versus flask-based estimation of carbon surface fluxes},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2009},
volume = {114},
doi = {10.1029/2009JD012311}
}
|
| Chevallier F, Ciais P, Conway TJ, Aalto T, Anderson BE, Bousquet P, Brunke EG, Ciattaglia L, Esaki Y, Froehlich M, Gomez A, Gomez-Pelaez AJ, Haszpra L, Krummel PB, Langenfelds RL, Leuenberger M, Machida T, Maignan F, Matsueda H, Morgui JA, Mukai H, Nakazawa T, Peylin P, Ramonet M, Rivier L, Sawa Y, Schmidt M, Steele LP, Vay SA, Vermeulen AT, Wofsy S and Worthy D ({2010}), "CO2 surface fluxes at grid point scale estimated from a global 21 year reanalysis of atmospheric measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 9, {2010}. Vol. {115} |
| Abstract: This paper documents a global Bayesian variational inversion of CO2 surface fluxes during the period 1988-2008. Weekly fluxes are estimated on a 3.75 degrees x 2.5 degrees (longitude-latitude) grid throughout the 21 years. The assimilated observations include 128 station records from three large data sets of surface CO2 mixing ratio measurements. A Monte Carlo approach rigorously quantifies the theoretical uncertainty of the inverted fluxes at various space and time scales, which is particularly important for proper interpretation of the inverted fluxes. Fluxes are evaluated indirectly against two independent CO2 vertical profile data sets constructed from aircraft measurements in the boundary layer and in the free troposphere. The skill of the inversion is evaluated by the improvement brought over a simple benchmark flux estimation based on the observed atmospheric growth rate. Our error analysis indicates that the carbon budget from the inversion should be more accurate than the a priori carbon budget by 20% to 60% for terrestrial fluxes aggregated at the scale of subcontinental regions in the Northern Hemisphere and over a year, but the inversion cannot clearly distinguish between the regional carbon budgets within a continent. On the basis of the independent observations, the inversion is seen to improve the fluxes compared to the benchmark: the atmospheric simulation of CO2 with the Bayesian inversion method is better by about 1 ppm than the benchmark in the free troposphere, despite possible systematic transport errors. The inversion achieves this improvement by changing the regional fluxes over land at the seasonal and at the interannual time scales. |
BibTeX:
@article{chevallier10a,
author = {Chevallier, F. and Ciais, P. and Conway, T. J. and Aalto, T. and Anderson, B. E. and Bousquet, P. and Brunke, E. G. and Ciattaglia, L. and Esaki, Y. and Froehlich, M. and Gomez, A. and Gomez-Pelaez, A. J. and Haszpra, L. and Krummel, P. B. and Langenfelds, R. L. and Leuenberger, M. and Machida, T. and Maignan, F. and Matsueda, H. and Morgui, J. A. and Mukai, H. and Nakazawa, T. and Peylin, P. and Ramonet, M. and Rivier, L. and Sawa, Y. and Schmidt, M. and Steele, L. P. and Vay, S. A. and Vermeulen, A. T. and Wofsy, S. and Worthy, D.},
title = {CO2 surface fluxes at grid point scale estimated from a global 21 year reanalysis of atmospheric measurements},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2010},
volume = {115},
doi = {10.1029/2010JD013887}
}
|
| Chevallier F, Wang T, Ciais P, Maignan F, Bocquet M, Arain MA, Cescatti A, Chen J, Dolman AJ, Law BE, Margolis HA, Montagnani L and Moors EJ ({2012}), "What eddy-covariance measurements tell us about prior land flux errors in CO2-flux inversion schemes", GLOBAL BIOGEOCHEMICAL CYCLES., MAR 10, {2012}. Vol. {26} |
| Abstract: To guide the future development of CO2-atmospheric inversion modeling systems, we analyzed the errors arising from prior information about terrestrial ecosystem fluxes. We compared the surface fluxes calculated by a process-based terrestrial ecosystem model with daily averages of CO2 flux measurements at 156 sites across the world in the FLUXNET network. At the daily scale, the standard deviation of the model-data fit was 2.5 gC.m(2).d(-1); temporal autocorrelations were significant at the weekly scale (>0.3 for lags less than four weeks), while spatial correlations were confined to within the first few hundred kilometers (<0.2 after 200 km). Separating out the plant functional types did not increase the spatial correlations, except for the deciduous broad-leaved forests. Using the statistics of the flux measurements as a proxy for the statistics of the prior flux errors was shown not to be a viable approach. A statistical model allowed us to upscale the site-level flux error statistics to the coarser spatial and temporal resolutions used in regional or global models. This approach allowed us to quantify how aggregation reduces error variances, while increasing correlations. As an example, for a typical inversion of grid point (300 km x 300 km) monthly fluxes, we found that the prior flux error follows an approximate e-folding correlation length of 500 km only, with correlations from one month to the next as large as 0.6. |
BibTeX:
@article{chevallier12a,
author = {Chevallier, Frederic and Wang, Tao and Ciais, Philippe and Maignan, Fabienne and Bocquet, Marc and Arain, M. Altaf and Cescatti, Alessandro and Chen, Jiquan and Dolman, A. Johannes and Law, Beverly E. and Margolis, Hank A. and Montagnani, Leonardo and Moors, Eddy J.},
title = {What eddy-covariance measurements tell us about prior land flux errors in CO2-flux inversion schemes},
journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
year = {2012},
volume = {26},
doi = {10.1029/2010GB003974}
}
|
| Chevallier F and O'Dell CW ({2013}), "Error statistics of Bayesian CO2 flux inversion schemes as seen from GOSAT", GEOPHYSICAL RESEARCH LETTERS., MAR 28, {2013}. Vol. {40}({6}), pp. 1252-1256. |
| Abstract: Statistical modeling is at the root of CO2 atmospheric inversion systems, but few studies have focused on the quality of their assigned probability distributions. In this paper, we assess the reliability of the error models that are in input and in output of a specific CO2 atmospheric inversion system when it assimilates surface air sample measurements. We confront these error models with the mismatch between 4D simulations of CO2 and independent satellite retrievals of the total CO2 column. Taking all sources of uncertainties into account, it is shown that both prior and posterior errors are consistent with the actual departures, to the point that the theoretical error reduction brought by the surface measurements on the simulation of the Greenhouse gases Observing SATellite (GOSAT) total column measurements (15 corresponds to the actual reduction seen over the midlatitude and tropical lands and over the tropical oceans. |
BibTeX:
@article{chevallier13a,
author = {Chevallier, Frederic and O'Dell, Christopher W.},
title = {Error statistics of Bayesian CO2 flux inversion schemes as seen from GOSAT},
journal = {GEOPHYSICAL RESEARCH LETTERS},
year = {2013},
volume = {40},
number = {6},
pages = {1252--1256},
doi = {10.1002/grl.50228}
}
|
| Chevallier F ({2013}), "On the parallelization of atmospheric inversions of CO2 surface fluxes within a variational framework", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {6}({3}), pp. 783-790. |
| Abstract: The variational formulation of Bayes' theorem allows inferring CO2 sources and sinks from atmospheric concentrations at much higher time-space resolution than the ensemble or analytical approaches. However, it usually exhibits limited scalable parallelism. This limitation hinders global atmospheric inversions operated on decadal time scales and regional ones with kilometric spatial scales because of the computational cost of the underlying transport model that has to be run at each iteration of the variational minimization. Here, we introduce a physical parallelization (PP) of variational atmospheric inversions. In the PP, the inversion still manages a single physically and statistically consistent window, but the transport model is run in parallel overlapping sub-segments in order to massively reduce the computation wall-clock time of the inversion. For global inversions, a simplification of transport modelling is described to connect the output of all segments. We demonstrate the performance of the approach on a global inversion for CO2 with a 32 yr inversion window (1979-2010) with atmospheric measurements from 81 sites of the NOAA global cooperative air sampling network. In this case, we show that the duration of the inversion is reduced by a seven-fold factor (from months to days), while still processing the three decades consistently and with improved numerical stability. |
BibTeX:
@article{chevallier13b,
author = {Chevallier, F.},
title = {On the parallelization of atmospheric inversions of CO2 surface fluxes within a variational framework},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2013},
volume = {6},
number = {3},
pages = {783--790},
doi = {10.5194/gmd-6-783-2013}
}
|
| Chevallier F (2013), "Report on the quality of the inverted CO2 fluxes", MACC-II delivrable D. Vol. 43 |
BibTeX:
@article{chevallier13c,
author = {F Chevallier},
title = {Report on the quality of the inverted CO2 fluxes},
journal = {MACC-II delivrable D},
year = {2013},
volume = {43},
url = {https://www-gmes-atmosphere-eu.ecmwf.int/documents/maccii/deliverables/ghg/MACCII_GHG_DEL_D43.4_20120430_Chevallier.pdf}
}
|
| Ciais P, Canadell JG, Luyssaert S, Chevallier F, Shvidenko A, Poussi Z, Jonas M, Peylin P, King AW, Schulze E-D, Piao S, Roedenbeck C, Peters W and Breon F-M ({2010}), "Can we reconcile atmospheric estimates of the Northern terrestrial carbon sink with land-based accounting?", CURRENT OPINION IN ENVIRONMENTAL SUSTAINABILITY., OCT, {2010}. Vol. {2}({4}), pp. 225-230. |
| Abstract: We estimate the northern hemisphere (NH) terrestrial carbon sink by comparing four recent atmospheric inversions with land-based C accounting data for six large northern regions. The mean NH terrestrial CO2 sink from the inversion models is 1.7 Pg C year(-1) over the period 2000-2004. The uncertainty of this estimate is based on the typical individual (1-sigma) precision of one inversion (0.9 Pg C year(-1)) and is consistent with the min-max range of the four inversion mean estimates (0.8 Pg C year(-1)). Inversions agree within their uncertainty for the distribution of the NH sink of CO2 in longitude, with Russia being the largest sink. The land-based accounting estimate of NH carbon sink is 1.7 Pg C year(-1) for the sum of the six regions studied. The 1-sigma uncertainty of the land-based estimate (0.3 Pg C year(-1)) is smaller than that of atmospheric inversions, but no independent land-based flux estimate is available to derive a `between accounting model' uncertainty. Encouragingly, the top-down atmospheric and the bottom-up land-based methods converge to consistent mean estimates within their respective errors, increasing the confidence in the overall budget. These results also confirm the continued critical role of NH terrestrial ecosystems in slowing down the atmospheric accumulation of anthropogenic CO2. |
BibTeX:
@article{ciais10a,
author = {Ciais, Philippe and Canadell, Josep G. and Luyssaert, Sebastiaan and Chevallier, Frederic and Shvidenko, Anatoly and Poussi, Zegbeu and Jonas, Matthias and Peylin, Philippe and King, Anthony Wayne and Schulze, Ernest-Detlef and Piao, Shilong and Roedenbeck, Christian and Peters, Wouter and Breon, Francois-Marie},
title = {Can we reconcile atmospheric estimates of the Northern terrestrial carbon sink with land-based accounting?},
journal = {CURRENT OPINION IN ENVIRONMENTAL SUSTAINABILITY},
year = {2010},
volume = {2},
number = {4},
pages = {225--230},
doi = {10.1016/j.cosust.2010.06.008}
}
|
| Ciais P, Dolman AJ, Bombelli A, Duren R, Peregon A, Rayner PJ, Miller C, Gobron N, Kinderman G, Marland G, Gruber N, Chevallier F, Andres RJ, Balsamo G, Bopp L, Breon FM, Broquet G, Dargaville R, Battin TJ, Borges A, Bovensmann H, Buchwitz M, Butler J, Canadell JG, Cook RB, DeFries R, Engelen R, Gurney KR, Heinze C, Heimann M, Held A, Henry M, Law B, Luyssaert S, Miller J, Moriyama T, Moulin C, Myneni RB, Nussli C, Obersteiner M, Ojima D, Pan Y, Paris JD, Piao SL, Poulter B, Plummer S, Quegan S, Raymond P, Reichstein M, Rivier L, Sabine C, Schimel D, Tarasova O, Valentini R, Wang R, van der Werf G, Wickland D, Williams M and Zehner C ({2014}), "Current systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system", BIOGEOSCIENCES. Vol. {11}({13}), pp. 3547-3602. |
| Abstract: A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observation system requires transformational advances from the existing sparse, exploratory framework towards a dense, robust, and sustained system in all components: anthropogenic emissions, the atmosphere, the ocean, and the terrestrial biosphere. The paper is addressed to scientists, policymakers, and funding agencies who need to have a global picture of the current state of the (diverse) carbon observations. We identify the current state of carbon observations, and the needs and notional requirements for a global integrated carbon observation system that can be built in the next decade. A key conclusion is the substantial expansion of the ground-based observation networks required to reach the high spatial resolution for CO2 and CH4 fluxes, and for carbon stocks for addressing policy-relevant objectives, and attributing flux changes to underlying processes in each region. In order to establish flux and stock diagnostics over areas such as the southern oceans, tropical forests, and the Arctic, in situ observations will have to be complemented with remote-sensing measurements. Remote sensing offers the advantage of dense spatial coverage and frequent revisit. A key challenge is to bring remote-sensing measurements to a level of long-term consistency and accuracy so that they can be efficiently combined in models to reduce uncertainties, in synergy with ground-based data. Bringing tight observational constraints on fossil fuel and land use change emissions will be the biggest challenge for deployment of a policy-relevant integrated carbon observation system. This will require in situ and remotely sensed data at much higher resolution and density than currently achieved for natural fluxes, although over a small land area (cities, industrial sites, power plants), as well as the inclusion of fossil fuel CO2 proxy measurements such as radiocarbon in CO2 and carbon-fuel combustion tracers. Additionally, a policy-relevant carbon monitoring system should also provide mechanisms for reconciling regional top-down (atmosphere-based) and bottom-up (surface-based) flux estimates across the range of spatial and temporal scales relevant to mitigation policies. In addition, uncertainties for each observation data-stream should be assessed. The success of the system will rely on long-term commitments to monitoring, on improved international collaboration to fill gaps in the current observations, on sustained efforts to improve access to the different data streams and make databases interoperable, and on the calibration of each component of the system to agreed-upon international scales. |
BibTeX:
@article{ciais14a,
author = {Ciais, P. and Dolman, A. J. and Bombelli, A. and Duren, R. and Peregon, A. and Rayner, P. J. and Miller, C. and Gobron, N. and Kinderman, G. and Marland, G. and Gruber, N. and Chevallier, F. and Andres, R. J. and Balsamo, G. and Bopp, L. and Breon, F. -M. and Broquet, G. and Dargaville, R. and Battin, T. J. and Borges, A. and Bovensmann, H. and Buchwitz, M. and Butler, J. and Canadell, J. G. and Cook, R. B. and DeFries, R. and Engelen, R. and Gurney, K. R. and Heinze, C. and Heimann, M. and Held, A. and Henry, M. and Law, B. and Luyssaert, S. and Miller, J. and Moriyama, T. and Moulin, C. and Myneni, R. B. and Nussli, C. and Obersteiner, M. and Ojima, D. and Pan, Y. and Paris, J. -D. and Piao, S. L. and Poulter, B. and Plummer, S. and Quegan, S. and Raymond, P. and Reichstein, M. and Rivier, L. and Sabine, C. and Schimel, D. and Tarasova, O. and Valentini, R. and Wang, R. and van der Werf, G. and Wickland, D. and Williams, M. and Zehner, C.},
title = {Current systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system},
journal = {BIOGEOSCIENCES},
year = {2014},
volume = {11},
number = {13},
pages = {3547--3602},
doi = {10.5194/bg-11-3547-2014}
}
|
| Cochran FV and Brunsell NA ({2012}), "Temporal scales of tropospheric CO2, precipitation, and ecosystem responses in the central Great Plains", REMOTE SENSING OF ENVIRONMENT., DEC, {2012}. Vol. {127}, pp. 316-328. |
| Abstract: Natural and anthropogenic sources of CO2 around the globe contribute to mid-tropospheric concentrations, yet it remains unknown how measurements of mid-tropospheric CO2 relate to regional ecosystem dynamics. NASA Atmospheric Infrared Sounder (AIRS) measurements of CO2 concentrations in the mid-troposphere from 2002 to 2010 were examined in relation to precipitation and vegetation phenology across the US Great Plains. Wavelet multi-resolution analysis and the information theory metric of relative entropy were applied to assess regional relationships between mid-tropospheric CO2, Normalized Difference Vegetation Index (NDVI), and precipitation (PPT). Results show that AIRS observations of mid-tropospheric CO2 exchange greater amounts of information with regional PPT and NDVI at seasonal, annual, and longer time scales compared to shorter time scales. PPT and NDVI contribute to mid-tropospheric CO2 at the 18-month time scale, while spatial patterns seen at this time scale for PIT and mid-tropospheric CO2 are reflective of the influence of PPT on NDVI at the annual scale. Identification of these dominant temporal scales may facilitate utilization of AIRS CO2 for monitoring regional source/sink dynamics related to climate and land-use/cover change. (c) 2012 Elsevier Inc. All rights reserved. |
BibTeX:
@article{cochran12a,
author = {Cochran, Ferdouz V. and Brunsell, Nathaniel A.},
title = {Temporal scales of tropospheric CO2, precipitation, and ecosystem responses in the central Great Plains},
journal = {REMOTE SENSING OF ENVIRONMENT},
year = {2012},
volume = {127},
pages = {316--328},
doi = {10.1016/j.rse.2012.09.012}
}
|
| Collalti A, Marconi S, Ibrom A, Trotta C, Anav A, D'Andrea E, Matteucci G, Montagnani L, Gielen B, Mammarella I, Gruenwald T, Knohl A, Berninger F, Zhao Y, Valentini R and Santini M ({2016}), "Validation of 3D-CMCC Forest Ecosystem Model (v.5.1) against eddy covariance data for 10 European forest sites", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {9}({2}), pp. 479-504. |
| Abstract: This study evaluates the performances of the new version (v.5.1) of 3D-CMCC Forest Ecosystem Model (FEM) in simulating gross primary productivity (GPP), against eddy covariance GPP data for 10 FLUXNET forest sites across Europe. A new carbon allocation module, coupled with new both phenological and autotrophic respiration schemes, was implemented in this new daily version. Model ability in reproducing timing and magnitude of daily and monthly GPP fluctuations is validated at intra-annual and inter-annual scale, including extreme anomalous seasons. With the purpose to test the 3D-CMCC FEM applicability over Europe without a site-related calibration, the model has been deliberately parametrized with a single set of species-specific parametrizations for each forest ecosystem. The model consistently reproduces both in timing and in magnitude daily and monthly GPP variability across all sites, with the exception of the two Mediterranean sites. We find that 3D-CMCC FEM tends to better simulate the timing of inter-annual anomalies than their magnitude within measurements' uncertainty. In six of eight sites where data are available, the model well reproduces the 2003 summer drought event. Finally, for three sites we evaluate whether a more accurate representation of forest structural characteristics (i.e. cohorts, forest layers) and species composition can improve model results. In two of the three sites results reveal that model slightly increases its performances although, statistically speaking, not in a relevant way. |
BibTeX:
@article{collalti16a,
author = {Collalti, A. and Marconi, S. and Ibrom, A. and Trotta, C. and Anav, A. and D'Andrea, E. and Matteucci, G. and Montagnani, L. and Gielen, B. and Mammarella, I. and Gruenwald, T. and Knohl, A. and Berninger, F. and Zhao, Y. and Valentini, R. and Santini, M.},
title = {Validation of 3D-CMCC Forest Ecosystem Model (v.5.1) against eddy covariance data for 10 European forest sites},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2016},
volume = {9},
number = {2},
pages = {479--504},
doi = {10.5194/gmd-9-479-2016}
}
|
| Combe M, de wit AJW, de Arellano JV-G, van der Molen MK, Magliulo V and Peters W ({2017}), "Grain Yield Observations Constrain Cropland CO2 Fluxes Over Europe", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., DEC, {2017}. Vol. {122}({12}), pp. {3238-3259}. |
| Abstract: Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models-most of which currently treat crops as unmanaged grasslands-is needed to improve atmospheric CO2 simulations. In the framework we present here, we model gross European cropland CO2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two-step procedure. In the first step, we calculate day-to-day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re-run our WOFOST model for the full European 25 x 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO2 fluxes with a simple soil respiration model to obtain the net cropland CO2 exchange. We assess our model's ability to represent cropland CO2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation-driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model. |
BibTeX:
@article{combe17a,
author = {Combe, M. and de wit, A. J. W. and de Arellano, J. Vila-Guerau and van der Molen, M. K. and Magliulo, V. and Peters, W.},
title = {Grain Yield Observations Constrain Cropland CO2 Fluxes Over Europe},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2017},
volume = {122},
number = {12},
pages = {3238-3259},
doi = {{10.1002/2017JG003937}}
}
|
| Cooley D, Breidt FJ, Ogle SM, Schuh AE and Lauvaux T ({2013}), "A constrained least-squares approach to combine bottom-up and top-down CO2 flux estimates", ENVIRONMENTAL AND ECOLOGICAL STATISTICS., MAR, {2013}. Vol. {20}({1}), pp. 129-146. |
| Abstract: Terrestrial CO2 flux estimates are obtained from two fundamentally different methods generally termed bottom-up and top-down approaches. Inventory methods are one type of bottom-up approach which uses various sources of information such as crop production surveys and forest monitoring data to estimate the annual CO2 flux at locations covering a study region. Top-down approaches are various types of atmospheric inversion methods which use CO2 concentration measurements from monitoring towers and atmospheric transport models to estimate CO2 flux over a study region. Both methods can also quantify the uncertainty associated with their estimates. Historically, these two approaches have produced estimates that differ considerably. The goal of this work is to construct a statistical model which sensibly combines estimates from the two approaches to produce a new estimate of CO2 flux for our study region. The two approaches have complementary strengths and weaknesses, and our results show that certain aspects of the uncertainty associated with each of the approaches are greatly reduced by combining the methods. Our model is purposefully simple and designed to take the two approaches' estimates and measures of uncertainty at `face value'. Specifically, we use a constrained least-squares approach to appropriately weigh the estimates by the inverse of their variance, and the constraint imposes agreement between the two sources. Our application involves nearly 18,000 flux estimates for the upper midwest United States. The constrained dependencies result in a non-sparse covariance matrix, but computation requires only minutes due to the structure of the model. |
BibTeX:
@article{cooley13a,
author = {Cooley, Daniel and Breidt, F. Jay and Ogle, Stephen M. and Schuh, Andrew E. and Lauvaux, Thomas},
title = {A constrained least-squares approach to combine bottom-up and top-down CO2 flux estimates},
journal = {ENVIRONMENTAL AND ECOLOGICAL STATISTICS},
year = {2013},
volume = {20},
number = {1},
pages = {129--146},
doi = {10.1007/s10651-012-0211-6}
}
|
| Corbin KD (2008), "Investigating causes of regional variations in atmospheric carbon dioxide concentrations". Thesis at: Colorado State University.
[BibTeX] |
BibTeX:
@phdthesis{corbin08a,
author = {Corbin, Katherine D},
title = {Investigating causes of regional variations in atmospheric carbon dioxide concentrations},
school = {Colorado State University},
year = {2008}
}
|
| Crevoisier C, Sweeney C, Gloor M, Sarmiento JL and Tans PP ({2010}), "Regional US carbon sinks from three-dimensional atmospheric CO2 sampling", PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA., OCT 26, {2010}. Vol. {107}({43}), pp. 18348-18353. |
| Abstract: Studies diverge substantially on the actual magnitude of the North American carbon budget. This is due to the lack of appropriate data and also stems from the difficulty to properly model all the details of the flux distribution and transport inside the region of interest. To sidestep these difficulties, we use here a simple budgeting approach to estimate land-atmosphere fluxes across North America by balancing the inflow and outflow of CO2 from the troposphere. We base our study on the unique sampling strategy of atmospheric CO2 vertical profiles over North America from the National Oceanic and Atmospheric Administration/Earth System Research Laboratory aircraft network, from which we infer the three-dimensional CO2 distribution over the continent. We find a moderate sink of 0.5 +/- 0.4 PgCy(-1) for the period 2004-2006 for the coterminous United States, in good agreement with the forest-inventory-based estimate of the first North American State of the Carbon Cycle Report, and averaged climate conditions. We find that the highest uptake occurs in the Midwest and in the Southeast. This partitioning agrees with independent estimates of crop uptake in the Midwest, which proves to be a significant part of the US atmospheric sink, and of secondary forest regrowth in the Southeast. Provided that vertical profile measurements are continued, our study offers an independent means to link regional carbon uptake to climate drivers. |
BibTeX:
@article{crevoisier10a,
author = {Crevoisier, Cyril and Sweeney, Colm and Gloor, Manuel and Sarmiento, Jorge L. and Tans, Pieter P.},
title = {Regional US carbon sinks from three-dimensional atmospheric CO2 sampling},
journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
year = {2010},
volume = {107},
number = {43},
pages = {18348--18353},
doi = {10.1073/pnas.0900062107}
}
|
| Crowell SMR, Kawa SR, Browell EV, Hammerling DM, Moore B, Schaefer K and Doney SC ({2018}), "On the Ability of Space-Based Passive and Active Remote Sensing Observations of CO2 to Detect Flux Perturbations to the Carbon Cycle", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 27, {2018}. Vol. {123}({2}), pp. {1460-1477}. |
| Abstract: Space-borne observations of CO2 are vital to gaining understanding of the carbon cycle in regions of the world that are difficult to measure directly, such as the tropical terrestrial biosphere, the high northern and southern latitudes, and in developing nations such as China. Measurements from passive instruments such as GOSAT and OCO-2, however, are constrained by solar zenith angle limitations as well as sensitivity to the presence of clouds and aerosols. Active measurements such as those in development for the Active Sensing of CO2 Emissions over Nights, Days and Seasons (ASCENDS) mission show strong potential for making measurements in the high-latitude winter and in cloudy regions. In this work we examine the enhanced flux constraint provided by the improved coverage from an active measurement such as ASCENDS. The simulation studies presented here show that with sufficient precision, ASCENDS will detect permafrost thaw and fossil fuel emissions shifts at annual and seasonal time scales, even in the presence of transport errors, representativeness errors, and biogenic flux errors. While OCO-2 can detect some of these perturbations at the annual scale, the seasonal sampling provided by ASCENDS provides the stronger constraint. Plain Language Summary Active and passive remote sensors show the potential to provide unprecedented information on the carbon cycle. With the all-season sampling, active remote sensors are more capable of constraining high-latitude emissions. The reduced sensitivity to cloud and aerosol also makes active sensors more capable of providing information in cloudy and polluted scenes with sufficient accuracy. These experiments account for errors that are fundamental to the top-down approach for constraining emissions, and even including these sources of error, we show that satellite remote sensors are critical for understanding the carbon cycle. |
BibTeX:
@article{crowell18a,
author = {Crowell, Sean M. R. and Kawa, S. Randolph and Browell, Edward V. and Hammerling, Dorit M. and Moore, Berrien and Schaefer, Kevin and Doney, Scott C.},
title = {On the Ability of Space-Based Passive and Active Remote Sensing Observations of CO2 to Detect Flux Perturbations to the Carbon Cycle},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2018},
volume = {123},
number = {2},
pages = {1460-1477},
doi = {{10.1002/2017JD027836}}
}
|
| Dang X, Lai C-T, Hollinger DY, Schauer AJ, Xiao J, Munger JW, Owensby C and Ehleringer JR ({2011}), "Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., SEP 20, {2011}. Vol. {116} |
| Abstract: We evaluated an idealized boundary layer (BL) model with simple parameterizations using vertical transport information from community model outputs (NCAR/NCEP Reanalysis and ECMWF Interim Analysis) to estimate regional-scale net CO2 fluxes from 2002 to 2007 at three forest and one grassland flux sites in the United States. The BL modeling approach builds on a mixed-layer model to infer monthly average net CO2 fluxes using high-precision mixing ratio measurements taken on flux towers. We compared BL model net ecosystem exchange (NEE) with estimates from two independent approaches. First, we compared modeled NEE with tower eddy covariance measurements. The second approach (EC-MOD) was a data-driven method that upscaled EC fluxes from towers to regions using MODIS data streams. Comparisons between modeled CO2 and tower NEE fluxes showed that modeled regional CO2 fluxes displayed interannual and intra-annual variations similar to the tower NEE fluxes at the Rannells Prairie and Wind River Forest sites, but model predictions were frequently different from NEE observations at the Harvard Forest and Howland Forest sites. At the Howland Forest site, modeled CO2 fluxes showed a lag in the onset of growing season uptake by 2 months behind that of tower measurements. At the Harvard Forest site, modeled CO2 fluxes agreed with the timing of growing season uptake but underestimated the magnitude of observed NEE seasonal fluctuation. This modeling inconsistency among sites can be partially attributed to the likely misrepresentation of atmospheric transport and/or CO2 gradients between ABL and the free troposphere in the idealized BL model. EC-MOD fluxes showed that spatial heterogeneity in land use and cover very likely explained the majority of the data-model inconsistency. We show a site-dependent atmospheric rectifier effect that appears to have had the largest impact on ABL CO2 inversion in the North American Great Plains. We conclude that a systematic BL modeling approach provided new insights when employed in multiyear, cross-site synthesis studies. These results can be used to develop diagnostic upscaling tools, improving our understanding of the seasonal and interannual variability of surface CO2 fluxes. |
BibTeX:
@article{dang11a,
author = {Dang, Xuerui and Lai, Chun-Ta and Hollinger, David Y. and Schauer, Andrew J. and Xiao, Jingfeng and Munger, J. William and Owensby, Clenton and Ehleringer, James R.},
title = {Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2011},
volume = {116},
doi = {10.1029/2010JG001554}
}
|
| Dang Y, Ren W, Tao B, Chen G, Lu C, Yang J, Pan S, Wang G, Li S and Tian H ({2014}), "Climate and Land Use Controls on Soil Organic Carbon in the Loess Plateau Region of China", PLOS ONE., MAY 1, {2014}. Vol. {9}({5}) |
| Abstract: The Loess Plateau of China has the highest soil erosion rate in the world where billion tons of soil is annually washed into Yellow River. In recent decades this region has experienced significant climate change and policy-driven land conversion. However, it has not yet been well investigated how these changes in climate and land use have affected soil organic carbon (SOC) storage on the Loess Plateau. By using the Dynamic Land Ecosystem Model (DLEM), we quantified the effects of climate and land use on SOC storage on the Loess Plateau in the context of multiple environmental factors during the period of 1961-2005. Our results show that SOC storage increased by 0.27 Pg C on the Loess Plateau as a result of multiple environmental factors during the study period. About 55% (0.14 Pg C) of the SOC increase was caused by land conversion from cropland to grassland/forest owing to the government efforts to reduce soil erosion and improve the ecological conditions in the region. Historical climate change reduced SOC by 0.05 Pg C (approximately 19% of the total change) primarily due to a significant climate warming and a slight reduction in precipitation. Our results imply that the implementation of ``Grain for Green'' policy may effectively enhance regional soil carbon storage and hence starve off further soil erosion on the Loess Plateau. |
BibTeX:
@article{dang14a,
author = {Dang, Yaai and Ren, Wei and Tao, Bo and Chen, Guangsheng and Lu, Chaoqun and Yang, Jia and Pan, Shufen and Wang, Guodong and Li, Shiqing and Tian, Hanqin},
title = {Climate and Land Use Controls on Soil Organic Carbon in the Loess Plateau Region of China},
journal = {PLOS ONE},
year = {2014},
volume = {9},
number = {5},
doi = {10.1371/journal.pone.0095548}
}
|
| Davidson GR, Phillips-Housley A and Stevens MT ({2013}), "Soil-zone adsorption of atmospheric CO2 as a terrestrial carbon sink", GEOCHIMICA ET COSMOCHIMICA ACTA., APR 1, {2013}. Vol. {106}, pp. 44-50. |
| Abstract: Identifying and quantifying sources and sinks of CO2 is integral to developing global carbon budgets and effectively modeling climate change. Adsorption of CO2 onto mineral and soil surfaces has generally been regarded as an insignificant sink, though few studies have investigated adsorption on natural materials at temperatures and CO2 concentrations relevant to atmospheric or soil zone conditions. In this study, annual adsorption at the scale of North America was modeled for the upper 3 m of the Earth's surface (the root zone) based on our own and published adsorption data, and results compared with reported estimates for the North American terrestrial carbon sink during 2000-2005. Our results suggest that adsorption can account for 1-3% of the average annual sink during these years. At smaller regional scales where more adsorptive deposits are present, such as volcanic ash or high-organic soils, the sink may be significantly larger. (C) 2013 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{davidson13a,
author = {Davidson, Gregg R. and Phillips-Housley, Ashley and Stevens, Maria T.},
title = {Soil-zone adsorption of atmospheric CO2 as a terrestrial carbon sink},
journal = {GEOCHIMICA ET COSMOCHIMICA ACTA},
year = {2013},
volume = {106},
pages = {44--50},
doi = {10.1016/j.gca.2012.12.015}
}
|
| Deng F and Chen JM ({2011}), "Recent global CO2 flux inferred from atmospheric CO2 observations and its regional analyses", BIOGEOSCIENCES. Vol. {8}({11}), pp. 3263-3281. |
| Abstract: The net surface exchange of CO2 for the years 2002-2007 is inferred from 12 181 atmospheric CO2 concentration data with a time-dependent Bayesian synthesis inversion scheme. Monthly CO2 fluxes are optimized for 30 regions of the North America and 20 regions for the rest of the globe. Although there have been many previous multiyear inversion studies, the reliability of atmospheric inversion techniques has not yet been systematically evaluated for quantifying regional interannual variability in the carbon cycle. In this study, the global interannual variability of the CO2 flux is found to be dominated by terrestrial ecosystems, particularly by tropical land, and the variations of regional terrestrial carbon fluxes are closely related to climate variations. These interannual variations are mostly caused by abnormal meteorological conditions in a few months in the year or part of a growing season and cannot be well represented using annual means, suggesting that we should pay attention to finer temporal climate variations in ecosystem modeling. We find that, excluding fossil fuel and biomass burning emissions, terrestrial ecosystems and oceans absorb an average of 3.63 +/- 0.49 and 1.94 +/- 0.41 PgC yr(-1), respectively. The terrestrial uptake is mainly in northern land while the tropical and southern lands contribute 0.62 +/- 0.47, and 0.67 +/- 0.34 PgC yr(-1) to the sink, respectively. In North America, terrestrial ecosystems absorb 0.89 +/- 0.18 PgC yr(-1) on average with a strong flux density found in the south-east of the continent. |
BibTeX:
@article{deng11a,
author = {Deng, F. and Chen, J. M.},
title = {Recent global CO2 flux inferred from atmospheric CO2 observations and its regional analyses},
journal = {BIOGEOSCIENCES},
year = {2011},
volume = {8},
number = {11},
pages = {3263--3281},
doi = {10.5194/bg-8-3263-2011}
}
|
| Deng F, Chen JM, Pan Y, Peters W, Birdsey R, McCullough K and Xiao J ({2013}), "The use of forest stand age information in an atmospheric CO2 inversion applied to North America", BIOGEOSCIENCES. Vol. {10}({8}), pp. 5335-5348. |
| Abstract: Atmospheric inversions have become an important tool in quantifying carbon dioxide (CO2) sinks and sources at a variety of spatiotemporal scales, but associated large uncertainties restrain the inversion research community from reaching agreement on many important subjects. We enhanced an atmospheric inversion of the CO2 flux for North America by introducing spatially explicit information on forest stand age for US and Canada as an additional constraint, since forest carbon dynamics are closely related to time since disturbance. To use stand age information in the inversion, we converted stand age into an age factor, and included the covariances between subcontinental regions in the inversion based on the similarity of the age factors. Our inversion results show that, considering age factors, regions with recently disturbed or old forests are often nudged towards carbon sources, while regions with middle-aged productive forests are shifted towards sinks. This conforms to stand age effects observed in flux networks. At the subcontinental level, our inverted carbon fluxes agree well with continuous estimates of net ecosystem carbon exchange (NEE) upscaled from eddy covariance flux data based on MODIS data. Inverted fluxes with the age constraint exhibit stronger correlation to these upscaled NEE estimates than those inverted without the age constraint. While the carbon flux at the continental and subcontinental scales is predominantly determined by atmospheric CO2 observations, the age constraint is shown to have potential to improve the inversion of the carbon flux distribution among subcontinental regions, especially for regions lacking atmospheric CO2 observations. |
BibTeX:
@article{deng13a,
author = {Deng, F. and Chen, J. M. and Pan, Y. and Peters, W. and Birdsey, R. and McCullough, K. and Xiao, J.},
title = {The use of forest stand age information in an atmospheric CO2 inversion applied to North America},
journal = {BIOGEOSCIENCES},
year = {2013},
volume = {10},
number = {8},
pages = {5335--5348},
doi = {10.5194/bg-10-5335-2013}
}
|
| Deng F, Jones DBA, Henze DK, Bousserez N, Bowman KW, Fisher JB, Nassar R, O'Dell C, Wunch D, Wennberg PO, Kort EA, Wofsy SC, Blumenstock T, Deutscher NM, Griffith DWT, Hase F, Heikkinen P, Sherlock V, Strong K, Sussmann R and Warneke T ({2014}), "Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({7}), pp. 3703-3727. |
| Abstract: We have examined the utility of retrieved column-averaged, dry-air mole fractions of CO2 (XCO2) from the Greenhouse Gases Observing Satellite (GOSAT) for quantifying monthly, regional flux estimates of CO2, using the GEOS-Chem four-dimensional variational (4D-Var) data assimilation system. We focused on assessing the potential impact of biases in the GOSAT CO2 data on the regional flux estimates. Using different screening and bias correction approaches, we selected three different subsets of the GOSAT XCO2 data for the 4D-Var inversion analyses, and found that the inferred global fluxes were consistent across the three XCO2 inversions. However, the GOSAT observational coverage was a challenge for the regional flux estimates. In the northern extratropics, the inversions were more sensitive to North American fluxes than to European and Asian fluxes due to the lack of observations over Eurasia in winter and over eastern and southern Asia in summer. The regional flux estimates were also sensitive to the treatment of the residual bias in the GOSAT XCO2 data. The largest differences obtained were for temperate North America and temperate South America, for which the largest spread between the inversions was 1.02 and 0.96 Pg C, respectively. In the case of temperate North America, one inversion suggested a strong source, whereas the second and third XCO2 inversions produced a weak and strong sink, respectively. Despite the discrepancies in the regional flux estimates between the three XCO2 inversions, the a posteriori CO2 distributions were in good agreement (with a mean difference between the three inversions of typically less than 0.5 ppm) with independent data from the Total Carbon Column Observing Network (TCCON), the surface flask network, and from the HIAPER Pole-to-Pole Observations (HIPPO) aircraft campaign. The discrepancy in the regional flux estimates from the different inversions, despite the agreement of the global flux estimates suggests the need for additional work to determine the minimum spatial scales at which we can reliably quantify the fluxes using GOSAT XCO2. The fact that the a posteriori CO2 from the different inversions were in good agreement with the independent data although the regional flux estimates differed significantly, suggests that innovative ways of exploiting existing data sets, and possibly additional observations, are needed to better evaluate the inferred regional flux estimates. |
BibTeX:
@article{deng14a,
author = {Deng, F. and Jones, D. B. A. and Henze, D. K. and Bousserez, N. and Bowman, K. W. and Fisher, J. B. and Nassar, R. and O'Dell, C. and Wunch, D. and Wennberg, P. O. and Kort, E. A. and Wofsy, S. C. and Blumenstock, T. and Deutscher, N. M. and Griffith, D. W. T. and Hase, F. and Heikkinen, P. and Sherlock, V. and Strong, K. and Sussmann, R. and Warneke, T.},
title = {Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2014},
volume = {14},
number = {7},
pages = {3703--3727},
doi = {10.5194/acp-14-3703-2014}
}
|
| Deng F, Jones DBA, O'Dell CW, Nassar R and Parazoo NC ({2016}), "Combining GOSAT XCO2 observations over land and ocean to improve regional CO2 flux estimates", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., FEB 27, {2016}. Vol. {121}({4}), pp. 1896-1913. |
| Abstract: We used the GEOS-Chem data assimilation system to examine the impact of combining Greenhouse Gases Observing Satellite (GOSAT) XCO2 data over land and ocean on regional CO2 flux estimates for 2010-2012. We found that compared to assimilating only land data, combining land and ocean data produced an a posteriori CO2 distribution that is in better agreement with independent data and fluxes that are in closer agreement with existing top-down and bottom-up estimates. Adding XCO2 data over oceans changed the tropical land regions from a source of 0.64PgC/yr to a sink of -0.60PgC/yr and produced a corresponding reduction in the estimated sink in northern and southern land regions by 0.49PgC/yr and 0.80PgC/yr, respectively. This highlights the importance of improved observational coverage in the tropics to better quantify the latitudinal distribution of the terrestrial fluxes. Based only on land XCO2 data, we estimated a strong source in northern tropical South America, which experienced wet conditions in 2010-2012. In contrast, with the land and ocean data, we estimated a sink for this wet region in the north, and a source for the seasonally dry regions in the south and east, which is consistent with our understanding of the impact of moisture availability on the carbon balance of the region. Our results suggest that using satellite data with a more zonally balanced observational coverage could help mitigate discrepancies in CO2 flux estimates; further improvement could be expected with the greater observational coverage provided by the Orbiting Carbon Observatory-2. |
BibTeX:
@article{deng16a,
author = {Deng, Feng and Jones, Dylan B. A. and O'Dell, Christopher W. and Nassar, Ray and Parazoo, Nicholas C.},
title = {Combining GOSAT XCO2 observations over land and ocean to improve regional CO2 flux estimates},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2016},
volume = {121},
number = {4},
pages = {1896--1913},
doi = {10.1002/2015JD024157}
}
|
| Deng A, Lauvaux T, Davis KJ, Gaudet BJ, Miles N, Richardson SJ, Wu K, Sarmiento DP, Hardesty RM and Bonin TA (2017), "Toward reduced transport errors in a high resolution urban CO2 inversion system", Elem Sci Anth. |
BibTeX:
@article{deng17a,
author = {Deng, Aijun and Lauvaux, Thomas and Davis, Kenneth J and Gaudet, Brian J and Miles, Natasha and Richardson, Scott J and Wu, Kai and Sarmiento, Daniel P and Hardesty, R Michael and Bonin, Timothy A},
title = {Toward reduced transport errors in a high resolution urban CO2 inversion system},
journal = {Elem Sci Anth},
year = {2017},
doi = {10.1525/elementa.133/}
}
|
| Desai AR, Helliker BR, Moorcroft PR, Andrews AE and Berry JA ({2010}), "Climatic controls of interannual variability in regional carbon fluxes from top-down and bottom-up perspectives", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., MAY 1, {2010}. Vol. {115} |
| Abstract: Observations of regional net ecosystem exchange (NEE) of CO(2) for 1997-2007 were analyzed for climatic controls on interannual variability (IAV). Quantifying IAV of regional (10(4)-10(6) km(2)) NEE over long time periods is key to understanding potential feedbacks between climate and the carbon cycle. Four independent techniques estimated monthly regional NEE for 10(4) km(2) in a spatially heterogeneous temperate-boreal transition region of the north central United States, centered on the Park Falls, Wisconsin, United States, National Oceanic and Atmospheric Administration tall tower site. These techniques included two bottom-up methods, based on flux tower upscaling and forest inventory based demographic modeling, respectively, and two top-down methods, based on tall tower equilibrium boundary layer budgets and tracer-transport inversion, respectively. While all four methods revealed a moderate carbon sink, they diverged significantly in magnitude. Coherence of relative magnitude and variability of NEE anomalies was strong across the methods. The strongest coherence was a trend of declining carbon sink since 2002. Most climatic controls were not strongly correlated with IAV. Significant controls on IAV were those related to hydrology, such as water table depth, and atmospheric CO(2). Weaker relationships were found with phenological controls such as autumn soil temperature. Hydrologic relationships were strongest with a 1 year lag, potentially highlighting a previously unrecognized predictor of IAV in this region. These results highlight a need for continued development of techniques to estimate regional IAV and incorporation of hydrologic cycling into couple carbon-climate models. |
BibTeX:
@article{desai10a,
author = {Desai, Ankur R. and Helliker, Brent R. and Moorcroft, Paul R. and Andrews, Arlyn E. and Berry, Joseph A.},
title = {Climatic controls of interannual variability in regional carbon fluxes from top-down and bottom-up perspectives},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2010},
volume = {115},
doi = {10.1029/2009JG001122}
}
|
| Desai AR, Moore DJP, Ahue WKM, Wilkes PTV, De Wekker SFJ, Brooks BG, Campos TL, Stephens BB, Monson RK, Burns SP, Quaife T, Aulenbach SM and Schimel DS ({2011}), "Seasonal pattern of regional carbon balance in the central Rocky Mountains from surface and airborne measurements", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., OCT 22, {2011}. Vol. {116} |
| Abstract: High-elevation forests represent a large fraction of potential carbon uptake in North America, but this uptake is not well constrained by observations. Additionally, forests in the Rocky Mountains have recently been severely damaged by drought, fire, and insect outbreaks, which have been quantified at local scales but not assessed in terms of carbon uptake at regional scales. The Airborne Carbon in the Mountains Experiment was carried out in 2007 partly to assess carbon uptake in western U. S. mountain ecosystems. The magnitude and seasonal change of carbon uptake were quantified by (1) paired upwind-downwind airborne CO2 observations applied in a boundary layer budget, (2) a spatially explicit ecosystem model constrained using remote sensing and flux tower observations, and (3) a downscaled global tracer transport inversion. Top-down approaches had mean carbon uptake equivalent to flux tower observations at a subalpine forest, while the ecosystem model showed less. The techniques disagreed on temporal evolution. Regional carbon uptake was greatest in the early summer immediately following snowmelt and tended to lessen as the region experienced dry summer conditions. This reduction was more pronounced in the airborne budget and inversion than in flux tower or upscaling, possibly related to lower snow water availability in forests sampled by the aircraft, which were lower in elevation than the tower site. Changes in vegetative greenness associated with insect outbreaks were detected using satellite reflectance observations, but impacts on regional carbon cycling were unclear, highlighting the need to better quantify this emerging disturbance effect on montane forest carbon cycling. |
BibTeX:
@article{desai11a,
author = {Desai, Ankur R. and Moore, David J. P. and Ahue, William K. M. and Wilkes, Phillip T. V. and De Wekker, Stephan F. J. and Brooks, Bjorn G. and Campos, Teresa L. and Stephens, Britton B. and Monson, Russell K. and Burns, Sean P. and Quaife, Tristan and Aulenbach, Steven M. and Schimel, David S.},
title = {Seasonal pattern of regional carbon balance in the central Rocky Mountains from surface and airborne measurements},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2011},
volume = {116},
doi = {10.1029/2011JG001655}
}
|
| Deutscher NM, Sherlock V, Fletcher SEM, Griffith DWT, Notholt J, Macatangay R, Connor BJ, Robinson J, Shiona H, Velazco VA, Wang Y, Wennberg PO and Wunch D ({2014}), "Drivers of column-average CO2 variability at Southern Hemispheric Total Carbon Column Observing Network sites", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({18}), pp. 9883-9901. |
| Abstract: We investigate factors that drive the variability in total column CO2 at the Total Carbon Column Observing Network sites in the Southern Hemisphere using fluxes tagged by process and by source region from the Carbon-Tracker analysed product as well as the Simple Biosphere model. We show that the terrestrial biosphere is the largest driver of variability in the Southern Hemisphere column CO2. However, it does not dominate in the same fashion as in the Northern Hemisphere. Local-and hemispheric-scale biomass burning can also play an important role, particularly at the tropical site, Darwin. The magnitude of seasonal variability in the column-average dry-air mole fraction of CO2, XCO2, is also much smaller in the Southern Hemisphere and comparable in magnitude to the annual increase. Comparison of measurements to the model simulations highlights that there is some discrepancy between the two time series, especially in the early part of the Darwin data record. We show that this mismatch is most likely due to erroneously estimated local fluxes in the Australian tropical region, which are associated with enhanced photosynthesis caused by early rainfall during the tropical monsoon season. |
BibTeX:
@article{deutscher14a,
author = {Deutscher, N. M. and Sherlock, V. and Fletcher, S. E. Mikaloff and Griffith, D. W. T. and Notholt, J. and Macatangay, R. and Connor, B. J. and Robinson, J. and Shiona, H. and Velazco, V. A. and Wang, Y. and Wennberg, P. O. and Wunch, D.},
title = {Drivers of column-average CO2 variability at Southern Hemispheric Total Carbon Column Observing Network sites},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2014},
volume = {14},
number = {18},
pages = {9883--9901},
doi = {10.5194/acp-14-9883-2014}
}
|
| Diallo M, Legras B, Ray E, Engel A and Anel JA ({2017}), "Global distribution of CO2 in the upper troposphere and stratosphere", ATMOSPHERIC CHEMISTRY AND PHYSICS., MAR 21, {2017}. Vol. {17}({6}), pp. 3861-3878. |
| Abstract: In this study, we construct a new monthly zonal mean carbon dioxide (CO2) distribution from the upper troposphere to the stratosphere over the 2000-2010 time period. This reconstructed CO2 product is based on a Lagrangian backward trajectory model driven by ERA-Interim reanalysis meteorology and tropospheric CO2 measurements. Comparisons of our CO2 product to extratropical in situ measurements from aircraft transects and balloon profiles show remarkably good agreement. The main features of the CO2 distribution include (1) relatively large mixing ratios in the tropical stratosphere; (2) seasonal variability in the extratropics, with relatively high mixing ratios in the summer and autumn hemisphere in the 15-20 km altitude layer; and (3) decreasing mixing ratios with increasing altitude from the upper troposphere to the middle stratosphere (similar to 35 km). These features are consistent with expected variability due to the transport of long-lived trace gases by the stratospheric Brewer-Dobson circulation. The method used here to construct this CO2 product is unique from other modelling efforts and should be useful for model and satellite validation in the upper troposphere and stratosphere as a prior for inversion modelling and to analyse features of stratosphere-troposphere exchange as well as the stratospheric circulation and its variability. |
BibTeX:
@article{diallo17a,
author = {Diallo, Mohamadou and Legras, Bernard and Ray, Eric and Engel, Andreas and Anel, Juan A.},
title = {Global distribution of CO2 in the upper troposphere and stratosphere},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {6},
pages = {3861--3878},
doi = {10.5194/acp-17-3861-2017}
}
|
| D\iaz-Isaac LI, Lauvaux T and Davis KJ (2018), "Impact of physical parameterizations and initial conditions on simulated atmospheric transport and CO2 mole fractions in the US Midwest", ATMOSPHERIC CHEMISTRY AND PHYSICS., 14835, 2018. Vol. 18, pp. 14813. |
BibTeX:
@article{diaz-isaac18a,
author = {Liza I. D\iaz-Isaac and Thomas Lauvaux and Kenneth J. Davis},
title = {Impact of physical parameterizations and initial conditions on simulated atmospheric transport and CO2 mole fractions in the US Midwest},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2018},
volume = {18},
pages = {14813},
url = {https://www.atmos-chem-phys.net/18/14813/2018/acp-18-14813-2018.pdf}
}
|
| Dils B, Buchwitz M, Reuter M, Schneising O, Boesch H, Parker R, Guerlet S, Aben I, Blumenstock T, Burrows JP, Butz A, Deutscher NM, Frankenberg C, Hase F, Hasekamp OP, Heymann J, De Maziere M, Notholt J, Sussmann R, Warneke T, Griffith D, Sherlock V and Wunch D ({2014}), "The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparative validation of GHG-CCI SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT CO2 and CH4 retrieval algorithm products with measurements from the TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {7}({6}), pp. 1723-1744. |
| Abstract: Column-averaged dry-air mole fractions of carbon dioxide and methane have been retrieved from spectra acquired by the TANSO-FTS (Thermal And Near-infrared Sensor for carbon Observations-Fourier Transform Spectrometer) and SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) instruments on board GOSAT (Greenhouse gases Observing SATellite) and ENVISAT (ENVIronmental SATellite), respectively, using a range of European retrieval algorithms. These retrievals have been compared with data from ground-based high-resolution Fourier transform spectrometers (FTSs) from the Total Carbon Column Observing Network (TCCON). The participating algorithms are the weighting function modified differential optical absorption spectroscopy (DOAS) algorithm (WFMD, University of Bremen), the Bremen optimal estimation DOAS algorithm (BESD, University of Bremen), the iterative maximum a posteriori DOAS (IMAP, Jet Propulsion Laboratory (JPL) and Netherlands Institute for Space Research algorithm (SRON)), the proxy and full-physics versions of SRON's RemoTeC algorithm (SRPR and SRFP, respectively) and the proxy and full-physics versions of the University of Leicester's adaptation of the OCO (Orbiting Carbon Observatory) algorithm (OCPR and OCFP, respectively). The goal of this algorithm inter-comparison was to identify strengths and weaknesses of the various so-called round-robin data sets generated with the various algorithms so as to determine which of the competing algorithms would proceed to the next round of the European Space Agency's (ESA) Greenhouse Gas Climate Change Initiative (GHG-CCI) project, which is the generation of the so-called Climate Research Data Package (CRDP), which is the first version of the Essential Climate Variable (ECV) ``greenhouse gases'' (GHGs). For XCO2, all algorithms reach the precision requirements for inverse modelling (< 8 ppm), with only WFMD having a lower precision (4.7 ppm) than the other algorithm products (2.4-2.5 ppm). When looking at the seasonal relative accuracy (SRA, variability of the bias in space and time), none of the algorithms have reached the demanding < 0.5 ppm threshold. For XCH4, the precision for both SCIAMACHY products (50.2 ppb for IMAP and 76.4 ppb for WFMD) fails to meet the < 34 ppb threshold for inverse modelling, but note that this work focusses on the period after the 2005 SCIAMACHY detector degradation. The GOSAT XCH4 precision ranges between 18.1 and 14.0 ppb. Looking at the SRA, all GOSAT algorithm products reach the < 10 ppm threshold (values ranging between 5.4 and 6.2 ppb). For SCIAMACHY, IMAP and WFMD have a SRA of 17.2 and 10.5 ppb, respectively. |
BibTeX:
@article{dils14a,
author = {Dils, B. and Buchwitz, M. and Reuter, M. and Schneising, O. and Boesch, H. and Parker, R. and Guerlet, S. and Aben, I. and Blumenstock, T. and Burrows, J. P. and Butz, A. and Deutscher, N. M. and Frankenberg, C. and Hase, F. and Hasekamp, O. P. and Heymann, J. and De Maziere, M. and Notholt, J. and Sussmann, R. and Warneke, T. and Griffith, D. and Sherlock, V. and Wunch, D.},
title = {The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparative validation of GHG-CCI SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT CO2 and CH4 retrieval algorithm products with measurements from the TCCON},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2014},
volume = {7},
number = {6},
pages = {1723--1744},
doi = {10.5194/amt-7-1723-2014}
}
|
| Doherty SJ, Bojinski S, Henderson-Sellers A, Noone K, Goodrich D, Bindoff NL, Church JA, Hibbard KA, Karl TR, Kajefez-Bogataj L, Lynch AH, Parker DE, Prentice IC, Ramaswamy V, Saunders RW, Smith MS, Steffen K, Stocker TF, Thorne PW, Trenberth KE, Verstraete MM and Zwiers FW ({2009}), "LESSONS LEARNED FROM IPCC AR4 Scientific Developments Needed To Understand, Predict, And Respond To Climate Change", BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY., APR, {2009}. Vol. {90}({4}), pp. 497-513. |
| Abstract: The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) concluded that global warming is ``unequivocal'' and that most of the observed increase since the mid-twentieth century is very likely due to the increase in anthropogenic greenhouse gas concentrations, with discernible human influences on ocean warming, continental-average temperatures, temperature extremes, wind patterns, and other physical and biological indicators, impacting both socioeconomic and ecological systems. It is now clear that we are committed to some level of global climate change, and it is imperative that this be considered when planning future climate research and observational strategies. The Global Climate Observing System program (GCOS), the World Climate Research Programme (WCRP), and the International Geosphere-Biosphere Programme (IGBP) therefore initiated a process to summarize the lessons learned through AR4 Working Groups I and II and to identify a set of high-priority modeling and observational needs. Two classes of recommendations emerged. First is the need to improve climate models, observational and climate monitoring systems, and our understanding of key processes. Second, the framework for climate research and observations must be extended to document impacts and to guide adaptation and mitigation efforts. Research and observational strategies specifically aimed at improving our ability to predict and understand impacts, adaptive capacity, and societal and ecosystem vulnerabilities will serve both purposes and are the subject of the specific recommendations made in this paper. |
BibTeX:
@article{doherty09a,
author = {Doherty, Sarah J. and Bojinski, Stephan and Henderson-Sellers, Ann and Noone, Kevin and Goodrich, David and Bindoff, Nathaniel L. and Church, John A. and Hibbard, Kathy A. and Karl, Thomas R. and Kajefez-Bogataj, Lucka and Lynch, Amanda H. and Parker, David E. and Prentice, I. Colin and Ramaswamy, Venkatachalam and Saunders, Roger W. and Smith, Mark Stafford and Steffen, Konrad and Stocker, Thomas F. and Thorne, Peter W. and Trenberth, Kevin E. and Verstraete, Michel M. and Zwiers, Francis W.},
title = {LESSONS LEARNED FROM IPCC AR4 Scientific Developments Needed To Understand, Predict, And Respond To Climate Change},
journal = {BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY},
year = {2009},
volume = {90},
number = {4},
pages = {497--513},
doi = {10.1175/2008BAMS2643.1}
}
|
| Dolman AJ, Gerbig C, Noilhan J, Sarrat C and Miglietta F ({2009}), "Detecting regional variability in sources and sinks of carbon dioxide: a synthesis", BIOGEOSCIENCES. Vol. {6}({6}), pp. 1015-1026. |
| Abstract: The current paper reviews the experimental setup of the CarboEurope Experimental Strategy (CERES) campaigns with the aim of providing an overview of the instrumentation used, the data-set and associated modelling. It then assesses progress in the field of regional observation and modelling of carbon fluxes, bringing the papers of this special issue into a somewhat broader context of analysis. Instrumental progress has been obtained in the field of remotely monitoring from tall towers and the experimental planning. Flux measurements from aircraft are now capable, within some constraints, to provide regular regional observations of fluxes of CO(2), latent and sensible heat. Considerable effort still needs to be put into calibrating the surface schemes of models, as they have direct impact on the input of energy, moisture and carbon fluxes in the boundary layer. Overall, the mesoscale models appear to be capable of simulating the large scale dynamics of the region, but in the fine detail, like the precise horizontal and vertical CO(2) field differences between the models still exist. These errors translate directly into transport uncertainty, when the forward simulations are used in inverse mode. Quantification of this uncertainty, including that of inadequate boundary layer height modelling, still remains a major challenge for state of the art mesoscale models. Progress in inverse models has been slow, but has shown that it is possible to estimate some of the errors involved, and that using the combination of observations. Overall, the capability to produce regional, high-resolution estimates of carbon exchange, exist in potential, but the routine application will require considerable effort, both in the experimental as in the modelling domain. |
BibTeX:
@article{dolman09a,
author = {Dolman, A. J. and Gerbig, C. and Noilhan, J. and Sarrat, C. and Miglietta, F.},
title = {Detecting regional variability in sources and sinks of carbon dioxide: a synthesis},
journal = {BIOGEOSCIENCES},
year = {2009},
volume = {6},
number = {6},
pages = {1015--1026},
doi = {10.5194/bg-6-1015-2009}
}
|
| Dolman AJ, van der Werf GR, van der Molen MK, Ganssen G, Erisman JW and Strengers B ({2010}), "A Carbon Cycle Science Update Since IPCC AR-4", AMBIO., JUL, {2010}. Vol. {39}({5-6}), pp. 402-412. |
| Abstract: We review important advances in our understanding of the global carbon cycle since the publication of the IPCC AR4. We conclude that: the anthropogenic emissions of CO2 due to fossil fuel burning have increased up through 2008 at a rate near to the high end of the IPCC emission scenarios; there are contradictory analyses whether an increase in atmospheric fraction, that might indicate a declining sink strength of ocean and/or land, exists; methane emissions are increasing, possibly through enhanced natural emission from northern wetland, methane emissions from dry plants are negligible; old-growth forest take up more carbon than expected from ecological equilibrium reasoning; tropical forest also take up more carbon than previously thought, however, for the global budget to balance, this would imply a smaller uptake in the northern forest; the exchange fluxes between the atmosphere and ocean are increasingly better understood and bottom up and observation-based top down estimates are getting closer to each other; the North Atlantic and Southern ocean take up less CO2, but it is unclear whether this is part of the `natural' decadal scale variability; large-scale fires and droughts, for instance in Amazonia, but also at Northern latitudes, have lead to significant decreases in carbon uptake on annual timescales; the extra uptake of CO2 stimulated by increased N-deposition is, from a greenhouse gas forcing perspective, counterbalanced by the related additional N2O emissions; the amount of carbon stored in permafrost areas appears much (two times) larger than previously thought; preservation of existing marine ecosystems could require a CO2 stabilization as low as 450 ppm; Dynamic Vegetation Models show a wide divergence for future carbon trajectories, uncertainty in the process description, lack of understanding of the CO2 fertilization effect and nitrogen-carbon interaction are major uncertainties. |
BibTeX:
@article{dolman10a,
author = {Dolman, A. J. and van der Werf, G. R. and van der Molen, M. K. and Ganssen, G. and Erisman, J. -W. and Strengers, B.},
title = {A Carbon Cycle Science Update Since IPCC AR-4},
journal = {AMBIO},
year = {2010},
volume = {39},
number = {5-6},
pages = {402--412},
doi = {10.1007/s13280-010-0083-7}
}
|
| Elias E, Dougherty M, Srivastava P and Laband D ({2013}), "The impact of forest to urban land conversion on streamflow, total nitrogen, total phosphorus, and total organic carbon inputs to the converse reservoir, Southern Alabama, USA", URBAN ECOSYSTEMS., MAR, {2013}. Vol. {16}({1, SI}), pp. 79-107. |
| Abstract: High total organic carbon (TOC) concentrations in Converse Reservoir, a water source for Mobile, Alabama, have concerned water treatment officials due to the potential for disinfection byproduct (DBP) formation. TOC reacts with chlorine during drinking water treatment to form DBPs. This study evaluated how increased urbanization can alter watershed-derived total nitrogen (TN), total phosphorus (TP) and TOC inputs to the Converse Reservoir. Converse Watershed, on the urban fringe of Mobile, is projected to undergo urbanization increasing watershed urban land from 3% in 1992 to 22% urban land by 2020. A pre-urbanization scenario using 1992 land cover was coupled with 2020 projections of land use. The Loading Simulation Program C++ watershed model was used to evaluate changes in nutrient concentrations (mg L-1) and loads (kg) to Converse Reservoir. Urban and suburban growth of 52 km(2) simulated from 1991 to 2005 (15 year) caused overall TN and TP loads to increase by 109 and 62 respectively. Simulated urban growth generally increased monthly flows by 15 but resulted in lower streamflows (2.9 during drought months. Results indicate that post-urbanization median TN and TP concentrations were 59 and 66br> higher than corresponding pre-urbanization concentrations, whereas TOC concentrations were 16% lower. An increase in urban flow caused TOC loads to increase by 26 despite lower post-urbanization TOC concentrations. |
BibTeX:
@article{elias13a,
author = {Elias, Emile and Dougherty, Mark and Srivastava, Puneet and Laband, David},
title = {The impact of forest to urban land conversion on streamflow, total nitrogen, total phosphorus, and total organic carbon inputs to the converse reservoir, Southern Alabama, USA},
journal = {URBAN ECOSYSTEMS},
year = {2013},
volume = {16},
number = {1, SI},
pages = {79--107},
doi = {10.1007/s11252-011-0198-z}
}
|
| Fadnavis S, Kumar KR, Tiwari YK and Pozzoli L ({2016}), "Atmospheric CO2 source and sink patterns over the Indian region", ANNALES GEOPHYSICAE. Vol. {34}({2}), pp. 279-291. |
| Abstract: In this paper we examine CO2 emission hot spots and sink regions over India as identified from global model simulations during the period 2000-2009. CO2 emission hot spots overlap with locations of densely clustered thermal power plants, coal mines and other industrial and urban centres; CO2 sink regions coincide with the locations of dense forest. Fossil fuel CO2 emissions are compared with two bottom-up inventories: the Regional Emission inventories in ASia (REAS v1.11; 2000-2009) and the Emission Database for Global Atmospheric Research (EDGAR v4.2) (2000-2009). Estimated fossil fuel emissions over the hot spot region are similar to 500-950 gCm(-2) yr(-1) as obtained from the global model simulation, EDGAR v4.2 and REAS v1.11 emission inventory. Simulated total fluxes show increasing trends, from 1.39 +/- 1.01br> yr(-1) (19.8 +/- 1.9 TgC yr(-1)) to 6.7 +/- 0.54% yr(-1) (97 +/- 12 TgC yr(-1)) over the hot spot regions and decreasing trends of -0.95 +/- 1.51% yr(-1) (-1 +/- 2 TgC yr(-1)) to 5.7 +/- 2.89% yr(-1) (-2.3 +/- 2 TgC yr(-1)) over the sink regions. Model-simulated terrestrial ecosystem fluxes show decreasing trends (increasing CO2 uptake) over the sink regions. Decreasing trends in terrestrial ecosystem fluxes imply that forest cover is increasing, which is consistent with India State of Forest Report (2009). Fossil fuel emissions show statistically significant increasing trends in all the data sets considered in this study. Estimated trend in simulated total fluxes over the Indian region is similar to 4.72 +/- 2.25% yr(-1) (25.6 TgC yr(-1)) which is slightly higher than global growth rate similar to 3.1-1) during 2000-2010. |
BibTeX:
@article{fadnavis16a,
author = {Fadnavis, Suvarna and Kumar, K. Ravi and Tiwari, Yogesh K. and Pozzoli, Luca},
title = {Atmospheric CO2 source and sink patterns over the Indian region},
journal = {ANNALES GEOPHYSICAE},
year = {2016},
volume = {34},
number = {2},
pages = {279--291},
doi = {10.5194/angeo-34-279-2016}
}
|
| Fang SX, Zhou LX, Tans PP, Ciais P, Steinbacher M, Xu L and Luan T ({2014}), "In situ measurement of atmospheric CO2 at the four WMO/GAW stations in China", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({5}), pp. 2541-2554. |
| Abstract: Atmospheric carbon dioxide (CO2) mole fractions were continuously measured from January 2009 to December 2011 at four atmospheric observatories in China using cavity ring-down spectroscopy instruments. The stations are Lin'an (LAN), Longfengshan (LFS), Shangdianzi (SDZ), and Waliguan (WLG), which are regional (LAN, LFS, SDZ) or global (WLG) measurement stations of the World Meteorological Organization's Global Atmosphere Watch program (WMO/ GAW). LAN is located near the megacity of Shanghai, in China's economically most developed region. LFS is in a forest and rice production area, close to the city of Harbin in northeastern China. SDZ is located 150 km northeast of Beijing. WLG, hosting the longest record of measured CO2 mole fractions in China, is a high-altitude site in northwestern China recording background CO2 concentration. The CO2 growth rates are 3.7 +/- 1.2 ppm yr(-1) for LAN, 2.7 +/- 0.8 ppm yr(-1) for LFS, 3.5 +/- 1.6 ppm yr(-1) for SDZ, and 2.2 +/- 0.8 ppm yr(-1) (1 sigma ) for WLG during the period of 2009 to 2011. The highest annual mean CO2 mole fraction of 404.2 +/- 3.9 ppm was observed at LAN in 2011. A comprehensive analysis of CO2 variations, their diurnal and seasonal cycles as well as the analysis of the influence of local sources on the CO2 mole fractions allows a characterization of the sampling sites and of the key processes driving the CO2 mole fractions. These data form a basis to improve our understanding of atmospheric CO2 variations in China and the underlying fluxes using atmospheric inversion models. |
BibTeX:
@article{fang14a,
author = {Fang, S. X. and Zhou, L. X. and Tans, P. P. and Ciais, P. and Steinbacher, M. and Xu, L. and Luan, T.},
title = {In situ measurement of atmospheric CO2 at the four WMO/GAW stations in China},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2014},
volume = {14},
number = {5},
pages = {2541--2554},
doi = {10.5194/acp-14-2541-2014}
}
|
| Fang Y, Michalak AM, Shiga YP and Yadav V ({2014}), "Using atmospheric observations to evaluate the spatiotemporal variability of CO2 fluxes simulated by terrestrial biospheric models", BIOGEOSCIENCES. Vol. {11}({23}), pp. 6985-6997. |
| Abstract: Terrestrial biospheric models (TBMs) are used to extrapolate local observations and process-level understanding of land-atmosphere carbon exchange to larger regions, and serve as predictive tools for examining carbon-climate interactions. Understanding the performance of TBMs is thus crucial to the carbon cycle and climate science communities. In this study, we present and assess an approach to evaluating the spatiotemporal patterns, rather than aggregated magnitudes, of net ecosystem exchange (NEE) simulated by TBMs using atmospheric CO2 measurements. The approach is based on statistical model selection implemented within a high-resolution atmospheric inverse model. Using synthetic data experiments, we find that current atmospheric observations are sensitive to the underlying spatiotemporal flux variability at sub-biome scales for a large portion of North America, and that atmospheric observations can therefore be used to evaluate simulated spatiotemporal flux patterns as well as to differentiate between multiple competing TBMs. Experiments using real atmospheric observations and four prototypical TBMs further confirm the applicability of the method, and demonstrate that the performance of TBMs in simulating the spatiotemporal patterns of NEE varies substantially across seasons, with best performance during the growing season and more limited skill during transition seasons. This result is consistent with previous work showing that the ability of TBMs to model flux magnitudes is also seasonally-dependent. Overall, the proposed approach provides a new avenue for evaluating TBM performance based on sub-biome-scale flux patterns, presenting an opportunity for assessing and informing model development using atmospheric observations. |
BibTeX:
@article{fang14b,
author = {Fang, Y. and Michalak, A. M. and Shiga, Y. P. and Yadav, V.},
title = {Using atmospheric observations to evaluate the spatiotemporal variability of CO2 fluxes simulated by terrestrial biospheric models},
journal = {BIOGEOSCIENCES},
year = {2014},
volume = {11},
number = {23},
pages = {6985--6997},
doi = {10.5194/bg-11-6985-2014}
}
|
| Fang Y and Michalak AM ({2015}), "Atmospheric observations inform CO2 flux responses to enviroclimatic drivers", GLOBAL BIOGEOCHEMICAL CYCLES., MAY, {2015}. Vol. {29}({5}), pp. 555-566. |
| Abstract: Understanding the response of the terrestrial biospheric carbon cycle to variability in enviroclimatic drivers is critical for predicting climate-carbon interactions. Here we apply an atmospheric-inversion-based framework to assess the relationships between the spatiotemporal patterns of net ecosystem CO2 exchange (NEE) and those of enviroclimatic drivers. We show that those relationships can be directly observed at 1 degrees x1 degrees 3-hourly resolution from atmospheric CO2 measurements for four of seven large biomes in North America, namely, (i) boreal forests and taiga; (ii) temperate coniferous forests; (iii) temperate grasslands, savannas, and shrublands; and (iv) temperate broadleaf and mixed forests. We find that shortwave radiation plays a dominant role during the growing season over all four biomes. Specific humidity and precipitation also play key roles and are associated with decreased CO2 uptake (or increased release). The explanatory power of specific humidity is especially strong during transition seasons, while that of precipitation appears during both the growing and dormant seasons. We further find that the ability of four prototypical terrestrial biospheric models (TBMs) to represent the spatiotemporal variability of NEE improves as the influence of radiation becomes more dominant, implying that TBMs have a better skill in representing the impact of radiation relative to other drivers. Even so, we show that TBMs underestimate the strength of the relationship to radiation and do not fully capture its seasonality. Furthermore, the TBMs appear to misrepresent the relationship to precipitation and specific humidity at the examined scales, with relationships that are not consistent in terms of sign, seasonality, or significance relative to observations. More broadly, we demonstrate the feasibility of directly probing relationships between NEE and enviroclimatic drivers at scales with no direct measurements of NEE, opening the door to the study of emergent processes across scales and to the evaluation of their scaling within TBMs. |
BibTeX:
@article{fang15a,
author = {Fang, Yuanyuan and Michalak, Anna M.},
title = {Atmospheric observations inform CO2 flux responses to enviroclimatic drivers},
journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
year = {2015},
volume = {29},
number = {5},
pages = {555--566},
doi = {10.1002/2014GB005034}
}
|
| Feldman DR, Collins WD, Gero PJ, Torn MS, Mlawer EJ and Shippert TR ({2015}), "Observational determination of surface radiative forcing by CO2 from 2000 to 2010", NATURE., MAR 19, {2015}. Vol. {519}({7543}), pp. {339+}. |
| Abstract: The climatic impact of CO2 and other greenhouse gases is usually quantified in terms of radiative forcing', calculated as the difference between estimates of the Earth's radiation field from pre-industrial and presentday concentrations of these gases. Radiative transfer models calculate that the increase in CO2 since 1750 corresponds to a global annualmean radiative forcing at the tropopause of 1.82 +/- 0.19W m(-2) (ref. 2). However, despite widespread scientific discussion and modelling of the climate impacts of well-mixed greenhouse gases, there is little direct observational evidence of the radiative impact of increasing atmospheric CO2. Here we present observationally based evidence of clear-sky CO2 surface radiative forcing that is directly attributable to the increase, between 2000 and 2010, of 22 parts per million atmospheric CO2. The time series of this forcing at the two locations the Southern Great Plains and the North Slope of Alaska are derived from Atmospheric Emitted Radiance Interferometer spectra' together with ancillary measurements and thoroughly corroborated radiative transfer calculations'. The time series both show statistically significant trends of 0.2 W m(-2) per decade (with respective uncertainties of +/- 0.06 W m(-2) per decade and 0.07 W m(-2) per decade) and have seasonal ranges of 0.1-0.2W m(-2). This is approximately ten per cent of the trend in downwelling longwave radiation'''. These results confirm theoretical predictions of the atmospheric greenhouse effect due to anthropogenic emissions, and provide empirical evidence of how rising CO2 levels, mediated by temporal variations due to photosynthesis and respiration, are affecting the surface energy balance. |
BibTeX:
@article{feldman15a,
author = {Feldman, D. R. and Collins, W. D. and Gero, P. J. and Torn, M. S. and Mlawer, E. J. and Shippert, T. R.},
title = {Observational determination of surface radiative forcing by CO2 from 2000 to 2010},
journal = {NATURE},
year = {2015},
volume = {519},
number = {7543},
pages = {339+},
doi = {10.1038/nature14240}
}
|
| Feldman DR, Collins WD, Biraud SC, Risser MD, Turner DD, Gero PJ, Tadic J, Helmig D, Xie S, Mlawer EJ, Shippert TR and Torn MS ({2018}), "Observationally derived rise in methane surface forcing mediated by water vapour trends", NATURE GEOSCIENCE. Vol. {11}({4}), pp. {238+}. |
| Abstract: Atmospheric methane (CH4) mixing ratios exhibited a plateau between 1995 and 2006 and have subsequently been increasing. While there are a number of competing explanations for the temporal evolution of this greenhouse gas, these prominent features in the temporal trajectory of atmospheric CH4 are expected to perturb the surface energy balance through radiative forcing, largely due to the infrared radiative absorption features of CH4. However, to date this has been determined strictly through radiative transfer calculations. Here, we present a quantified observation of the time series of clear-sky radiative forcing by CH4 at the surface from 2002 to 2012 at a single site derived from spectroscopic measurements along with line-by-line calculations using ancillary data. There was no significant trend in CH4 forcing between 2002 and 2006, but since then, the trend in forcing was 0.026 +/- 0.006 (99.7% CI) W m(2) yr(-1). The seasonal-cycle amplitude and secular trends in observed forcing are influenced by a corresponding seasonal cycle and trend in atmospheric CH4. However, we find that we must account for the overlapping absorption effects of atmospheric water vapour (H2O) and CH4 to explain the observations fully. Thus, the determination of CH4 radiative forcing requires accurate observations of both the spatiotemporal distribution of CH4 and the vertically resolved trends in H2O. |
BibTeX:
@article{feldman18a,
author = {Feldman, D. R. and Collins, W. D. and Biraud, S. C. and Risser, M. D. and Turner, D. D. and Gero, P. J. and Tadic, J. and Helmig, D. and Xie, S. and Mlawer, E. J. and Shippert, T. R. and Torn, M. S.},
title = {Observationally derived rise in methane surface forcing mediated by water vapour trends},
journal = {NATURE GEOSCIENCE},
year = {2018},
volume = {11},
number = {4},
pages = {238+},
doi = {{10.1038/s41561-018-0085-9}}
}
|
| Feltz ML, Knuteson RO and Revercomb HE ({2017}), "Assessment of COSMIC radio occultation and AIRS hyperspectral IR sounder temperature products in the stratosphere using observed radiances", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., AUG 27, {2017}. Vol. {122}({16}), pp. 8593-8616. |
| Abstract: Upper air temperature is defined as an essential climate variable by the World Meteorological Organization. Two remote sensing technologies being promoted for monitoring stratospheric temperatures are GPS radio occultation (RO) and spectrally resolved IR radiances. This study assesses RO and hyperspectral IR sounder derived temperature products within the stratosphere by comparing IR spectra calculated from GPS RO and IR sounder products to coincident IR observed radiances, which are used as a reference standard. RO dry temperatures from the University Corporation for Atmospheric Research (UCAR) Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission are compared to NASA Atmospheric Infrared Sounder (AIRS) retrievals using a previously developed profile-to-profile collocation method and vertical temperature averaging kernels. Brightness temperatures (BTs) are calculated for both COSMIC and AIRS temperature products and are then compared to coincident AIRS measurements. The COSMIC calculated minus AIRS measured BTs exceed the estimated 0.5 K measurement uncertainty for the winter time extratropics around 35 hPa. These differences are attributed to seasonal UCAR COSMIC biases. Unphysical vertical oscillations are seen in the AIRS L2 temperature product in austral winter Antarctic regions, and results imply a small AIRS tropical warm bias around similar to 35 hPa in the middle stratosphere. |
BibTeX:
@article{feltz17a,
author = {Feltz, M. L. and Knuteson, R. O. and Revercomb, H. E.},
title = {Assessment of COSMIC radio occultation and AIRS hyperspectral IR sounder temperature products in the stratosphere using observed radiances},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2017},
volume = {122},
number = {16},
pages = {8593--8616},
doi = {10.1002/2017JD026704}
}
|
| Flower CE and Gonzalez-Meler MA ({2015}), "Responses of Temperate Forest Productivity to Insect and Pathogen Disturbances", In ANNUAL REVIEW OF PLANT BIOLOGY, VOL 66. Vol. {66}, pp. 547-569. Annual Reviews. |
| Abstract: Pest and pathogen disturbances are ubiquitous across forest ecosystems, impacting their species composition, structure, and function. Whereas severe abiotic disturbances (e.g., clear-cutting and fire) largely reset successional trajectories, pest and pathogen disturbances cause diffuse mortality, driving forests into nonanalogous system states. Biotic perturbations that disrupt forest carbon dynamics either reduce or enhance net primary production (NPP) and carbon storage, depending on pathogen type. Relative to defoliators, wood borers and invasive pests have the largest negative impact on NPP and the longest recovery time. Forest diversity is an important contributing factor to productivity: NPP is neutral, marginally enhanced, or reduced in high-diversity stands in which a small portion of the canopy is affected (temperate deciduous or mixed forests) but very negative in low-diversity stands in which a large portion of the canopy is affected (western US forests). Pests and pathogens reduce forest structural and functional redundancy, affecting their resilience to future climate change or new outbreaks. Therefore, pests and pathogens can be considered biotic forcing agents capable of causing consequences of similar magnitude to climate forcing factors. |
BibTeX:
@incollection{flower15a,
author = {Flower, Charles E. and Gonzalez-Meler, Miquel A.},
editor = {Merchant, SS},
title = {Responses of Temperate Forest Productivity to Insect and Pathogen Disturbances},
booktitle = {ANNUAL REVIEW OF PLANT BIOLOGY, VOL 66},
publisher = {Annual Reviews},
year = {2015},
volume = {66},
pages = {547--569},
doi = {10.1146/annurev-arplant-043014-115540}
}
|
| Font A, Morgui JA, Curcoll R, Pouchet I, Casals I and Rodo X ({2010}), "Daily carbon surface fluxes in the West Ebre (Ebro) watershed from aircraft profiling on late June 2007", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 427-440. |
| Abstract: An intensive aircraft campaign measuring atmospheric CO(2) mixing ratios was carried out in the central part of the Ebre watershed on late June 2007 to characterize the CO(2) dynamics in the Ebre basin and to calculate the regional cumulative carbon surface flux. CO(2) concentrations were obtained from vertical profiles over La Muela (LMU; 41.60 degrees N, 1.1 degrees W) from 900 to 4000 m above the sea level (masl), horizontal transects at similar to 2000 m 100 km west from LMU, and continuous measurements at similar to 650 masl. Different estimates of surface flux from changes in the convective boundary layer (CBL) CO(2) concentration were obtained following the Integral CBL budgeting equation (ICBL) and the carbon content integration (CCI) method. Values of the mean surface flux calculated from the different approaches range from -2.4 to -7.9 mu molCO(2)/m2s. Regional surface flux calculated from vertical profiling appears to be consistent in a distance of 70 km away from the measurement site. The ICBL method is very sensitive to the accurate determination of the concentration in the entrainment zone. The overall uncertainty from fluxes calculated from the ICBL method rises to a value of 70 whereas the uncertainty linked to the CCI method is 55%. |
BibTeX:
@article{font10a,
author = {Font, A. and Morgui, J. -A. and Curcoll, R. and Pouchet, I. and Casals, I. and Rodo, X.},
title = {Daily carbon surface fluxes in the West Ebre (Ebro) watershed from aircraft profiling on late June 2007},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2010},
volume = {62},
number = {5, SI},
pages = {427--440},
doi = {10.1111/j.1600-0889.2010.00469.x}
}
|
| Font A, Morgui JA and Rodo X ({2011}), "Assessing the regional surface influence through Backward Lagrangian Dispersion Models for aircraft CO2 vertical profiles observations in NE Spain", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({4}), pp. 1659-1670. |
| Abstract: In this study the differences in the measured atmospheric CO2 mixing ratio at three aircraft profiling sites in NE Spain separated by 60 km are analyzed in regard to the variability of the surface fluxes in the regional surface influence area. First, the Regional Potential Surface Influence (RPSI) for fifty-one days in 2006 is calculated to assess the vertical, horizontal and temporal extent of the surface influence for the three sites at the regional scale (10(4) km(2)) at different altitudes of the profile (600, 1200, 2500 and 4000 meters above the sea level, ma.s.l.). Second, three flights carried out in 2006 (7 February, 24 August and 29 November) following the Crown Atmospheric Sampling (CAS) design are presented to study the relation between the measured CO2 variability and the Potential Surface Influence (PSI) and RPSI concepts. At 600 and 1200 ma.s.l. the regional signal is confined up to 50 h before the measurements whereas at higher altitudes (2500 and 4000 ma.s.l.) the regional surface influence is only recovered during spring and summer months. The RPSI from sites separated by similar to 60 km overlap by up to 70% of the regional surface influence at 600 and 1200 ma.s.l., while the overlap decreases to 10-40% at higher altitudes (2500 and 4000 ma.s.l.). The scale of the RPSI area is suitable to understand the differences in the measured CO2 concentration in the three vertices of the CAS, as CO2 differences are attributed to local surrounding fluxes (February) or to the variability of regional surface influence as for the August and November flights. For these two flights, the variability in the regional scale influences the variability measured in the local scale. The CAS sampling design for aircraft measurements appears to be a suitable method to cope with the variability of a typical grid for inversion models as measurements are intensified within the PBL and the background concentration is measured every similar to 10(2) km. |
BibTeX:
@article{font11a,
author = {Font, A. and Morgui, J. -A. and Rodo, X.},
title = {Assessing the regional surface influence through Backward Lagrangian Dispersion Models for aircraft CO2 vertical profiles observations in NE Spain},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2011},
volume = {11},
number = {4},
pages = {1659--1670},
doi = {10.5194/acp-11-1659-2011}
}
|
| Foucher PY, Chedin A, Armante R, Boone C, Crevoisier C and Bernath P ({2011}), "Carbon dioxide atmospheric vertical profiles retrieved from space observation using ACE-FTS solar occultation instrument", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({6}), pp. 2455-2470. |
| Abstract: Major limitations of our present knowledge of the global distribution of CO2 in the atmosphere are the uncertainty in atmospheric transport and the sparseness of in situ concentration measurements. Limb viewing spaceborne sounders such as the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) offer a vertical resolution of a few kilometres for profiles, which is much better than currently flying or planned nadir sounding instruments can achieve. After having demonstrated the feasibility of obtaining CO2 vertical profiles in the 5-25 km altitude range with an accuracy of about 2 ppm in a previous study, we present here the results of five years of ACE-FTS observations in terms of monthly mean profiles of CO2 averaged over 10 degrees latitude bands for northern mid-latitudes. These results are compared with in-situ aircraft measurements and with simulations from two different air transport models. Key features of the measured altitude distribution of CO2 are shown to be accurately reproduced by the ACE-FTS retrievals: variation in altitude of the seasonal cycle amplitude and extrema, seasonal change of the vertical gradient, and mean growth rate. We show that small but significant differences from model simulations could result from an over estimation of the model circulation strength during the northern hemisphere spring. Coupled with column measurements from a nadir viewing instrument, it is expected that occultation measurements will bring useful constraints to the surface carbon flux determination. |
BibTeX:
@article{foucher11a,
author = {Foucher, P. Y. and Chedin, A. and Armante, R. and Boone, C. and Crevoisier, C. and Bernath, P.},
title = {Carbon dioxide atmospheric vertical profiles retrieved from space observation using ACE-FTS solar occultation instrument},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2011},
volume = {11},
number = {6},
pages = {2455--2470},
doi = {10.5194/acp-11-2455-2011}
}
|
| Frankenberg C, Bergamaschi P, Butz A, Houweling S, Meirink JF, Notholt J, Petersen AK, Schrijver H, Warneke T and Aben I ({2008}), "Tropical methane emissions: A revised view from SCIAMACHY onboard ENVISAT", GEOPHYSICAL RESEARCH LETTERS., AUG 12, {2008}. Vol. {35}({15}) |
| Abstract: Methane retrievals from near-infrared spectra recorded by the SCIAMACHY instrument onboard ENVISAT hitherto suggested unexpectedly large tropical emissions. Even though recent studies confirm substantial tropical emissions, there were indications for an unresolved error in the satellite retrievals. Here we identify a retrieval error related to inaccuracies in water vapor spectroscopic parameters, causing a substantial overestimation of methane correlated with high water vapor abundances. We report on the overall implications of an update in water spectroscopy on methane retrievals with special focus on the tropics where the impact is largest. The new retrievals are applied in a four-dimensional variational (4D-VAR) data assimilation system to derive a first estimate of the impact on tropical CH(4) sources. Compared to inversions based on previous SCIAMACHY retrievals, annual tropical emission estimates are reduced from 260 to about 201 Tg CH(4) but still remain higher than previously anticipated. |
BibTeX:
@article{frankenberg08a,
author = {Frankenberg, Christian and Bergamaschi, Peter and Butz, Andre and Houweling, Sander and Meirink, Jan Fokke and Notholt, Justus and Petersen, Anna Katinka and Schrijver, Hans and Warneke, Thorsten and Aben, Ilse},
title = {Tropical methane emissions: A revised view from SCIAMACHY onboard ENVISAT},
journal = {GEOPHYSICAL RESEARCH LETTERS},
year = {2008},
volume = {35},
number = {15},
doi = {10.1029/2008GL034300}
}
|
| Frankenberg C, Aben I, Bergamaschi P, Dlugokencky EJ, van Hees R, Houweling S, van der Meer P, Snel R and Tol P ({2011}), "Global column-averaged methane mixing ratios from 2003 to 2009 as derived from SCIAMACHY: Trends and variability", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., FEB 17, {2011}. Vol. {116} |
| Abstract: After a decade of stable or slightly decreasing global methane concentrations, ground-based in situ data show that CH4 began increasing again in 2007 and that this increase continued through 2009. So far, space-based retrievals sensitive to the lower troposphere in the time period under consideration have not been available. Here we report a long-term data set of column-averaged methane mixing ratios retrieved from spectra of the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instrument onboard Envisat. The retrieval quality after 2005 was severely affected by degrading detector pixels within the methane 2v(3) absorption band. We identified the most crucial problems in SCIAMACHY detector degradation and overcame the problem by applying a strict pixel mask as well as a new dark current characterization. Even though retrieval precision after the end of 2005 is invariably degraded, consistent methane retrievals from 2003 through 2009 are now possible. Regional time series in the Sahara, Australia, tropical Africa, South America, and Asia show the methane increase in 2007-2009, but we cannot yet draw a firm conclusion concerning the origin of the increase. Tropical Africa even seems to exhibit a negative anomaly in 2006, but an impact from changes in SCIAMACHY detector degradation cannot be excluded yet. Over Assakrem, Algeria, we observed strong similarities between SCIAMACHY measurements and ground-based data in deseasonalized time series. We further show long-term SCIAMACHY xCH(4) averages at high spatial resolution that provide further insight into methane variations on regional scales. The Red Basin in China exhibits, on average, the highest methane abundance worldwide, while other localized features such as the Sudd wetlands in southern Sudan can also be identified in SCIAMACHY xCH(4) averages. |
BibTeX:
@article{frankenberg11a,
author = {Frankenberg, C. and Aben, I. and Bergamaschi, P. and Dlugokencky, E. J. and van Hees, R. and Houweling, S. and van der Meer, P. and Snel, R. and Tol, P.},
title = {Global column-averaged methane mixing ratios from 2003 to 2009 as derived from SCIAMACHY: Trends and variability},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2010JD014849}
}
|
| Frankenberg C, Kulawik SS, Wofsy SC, Chevallier F, Daube B, Kort EA, O'Dell C, Olsen ET and Osterman G ({2016}), "Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {16}({12}), pp. 7867-7878. |
| Abstract: In recent years, space-borne observations of atmospheric carbon dioxide (CO2) have been increasingly used in global carbon-cycle studies. In order to obtain added value from space-borne measurements, they have to suffice stringent accuracy and precision requirements, with the latter being less crucial as it can be reduced by just enhanced sample size. Validation of CO2 column-averaged dry air mole fractions (XCO2) heavily relies on measurements of the Total Carbon Column Observing Network (TCCON). Owing to the sparseness of the network and the requirements imposed on space-based measurements, independent additional validation is highly valuable. Here, we use observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) flights from 01/2009 through 09/2011 to validate CO2 measurements from satellites (Greenhouse Gases Observing Satellite - GOSAT, Thermal Emission Sounder - TES, Atmospheric Infrared Sounder - AIRS) and atmospheric inversion models (CarbonTracker CT2013B, Monitoring Atmospheric Composition and Climate (MACC) v13r1). We find that the atmospheric models capture the XCO2 variability observed in HIPPO flights very well, with correlation coefficients (r(2)) of 0.93 and 0.95 for CT2013B and MACC, respectively. Some larger discrepancies can be observed in profile comparisons at higher latitudes, in particular at 300aEuro-hPa during the peaks of either carbon uptake or release. These deviations can be up to 4aEuro-ppm and hint at misrepresentation of vertical transport. Comparisons with the GOSAT satellite are of comparable quality, with an r(2) of 0.85, a mean bias mu of -0.06aEuro-ppm, and a standard deviation sigma of 0.45aEuro-ppm. TES exhibits an r(2) of 0.75, mu of 0.34aEuro-ppm, and sigma of 1.13aEuro-ppm. For AIRS, we find an r(2) of 0.37, mu of 1.11aEuro-ppm, and sigma of 1.46aEuro-ppm, with latitude-dependent biases. For these comparisons at least 6, 20, and 50 atmospheric soundings have been averaged for GOSAT, TES, and AIRS, respectively. Overall, we find that GOSAT soundings over the remote Pacific Ocean mostly meet the stringent accuracy requirements of about 0.5aEuro-ppm for space-based CO2 observations. |
BibTeX:
@article{frankenberg16a,
author = {Frankenberg, Christian and Kulawik, Susan S. and Wofsy, Steven C. and Chevallier, Frederic and Daube, Bruce and Kort, Eric A. and O'Dell, Christopher and Olsen, Edward T. and Osterman, Gregory},
title = {Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2016},
volume = {16},
number = {12},
pages = {7867--7878},
doi = {10.5194/acp-16-7867-2016}
}
|
| Fraser A, Palmer PI, Feng L, Boesch H, Cogan A, Parker R, Dlugokencky EJ, Fraser PJ, Krummel PB, Langenfelds RL, O'Doherty S, Prinn RG, Steele LP, van der Schoot M and Weiss RF ({2013}), "Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({11}), pp. 5697-5713. |
| Abstract: We use an ensemble Kalman filter (EnKF), together with the GEOS-Chem chemistry transport model, to estimate regional monthly methane (CH4) fluxes for the period June 2009-December 2010 using proxy dry-air column-averaged mole fractions of methane (XCH4) from GOSAT (Greenhouse gases Observing SATellite) and/or NOAA ESRL (Earth System Research Laboratory) and CSIRO GASLAB (Global Atmospheric Sampling Laboratory) CH4 surface mole fraction measurements. Global posterior estimates using GOSAT and/or surface measurements are between 510-516 Tg yr(-1), which is less than, though within the uncertainty of, the prior global flux of 529 +/- 25 Tg yr(-1). We find larger differences between regional prior and posterior fluxes, with the largest changes in monthly emissions (75 Tg yr(-1)) occurring in Temperate Eurasia. In non-boreal regions the error reductions for inversions using the GOSAT data are at least three times larger (up to 45 than if only surface data are assimilated, a reflection of the greater spatial coverage of GOSAT, with the two exceptions of latitudes >60 degrees associated with a data filter and over Europe where the surface network adequately describes fluxes on our model spatial and temporal grid. We use CarbonTracker and GEOS-Chem XCO2 model output to investigate model error on quantifying proxy GOSAT XCH4 (involving model XCO2) and inferring methane flux estimates from surface mole fraction data and show similar resulting fluxes, with differences reflecting initial differences in the proxy value. Using a series of observing system simulation experiments (OSSEs) we characterize the posterior flux error introduced by non-uniform atmospheric sampling by GOSAT. We show that clear-sky measurements can theoretically reproduce fluxes within 10% of true values, with the exception of tropical regions where, due to a large seasonal cycle in the number of measurements because of clouds and aerosols, fluxes are within 15% of true fluxes. We evaluate our posterior methane fluxes by incorporating them into GEOS-Chem and sampling the model at the location and time of surface CH4 measurements from the AGAGE (Advanced Global Atmospheric Gases Experiment) network and column XCH4 measurements from TCCON (Total Carbon Column Observing Network). The posterior fluxes modestly improve the model agreement with AGAGE and TCCON data relative to prior fluxes, with the correlation coefficients (r(2)) increasing by a mean of 0.04 (range: -0.17 to 0.23) and the biases decreasing by a mean of 0.4 ppb (range: -8.9 to 8.4 ppb). |
BibTeX:
@article{fraser13a,
author = {Fraser, A. and Palmer, P. I. and Feng, L. and Boesch, H. and Cogan, A. and Parker, R. and Dlugokencky, E. J. and Fraser, P. J. and Krummel, P. B. and Langenfelds, R. L. and O'Doherty, S. and Prinn, R. G. and Steele, L. P. and van der Schoot, M. and Weiss, R. F.},
title = {Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {11},
pages = {5697--5713},
doi = {10.5194/acp-13-5697-2013}
}
|
| Fu D, Chen B, Zhang H, Wang J, Black TA, Amiro BD, Bohrer G, Bolstad P, Coulter R, Rahman AF, Dunn A, McCaughey JH, Meyers T and Verma S ({2014}), "Estimating landscape net ecosystem exchange at high spatial-temporal resolution based on Landsat data, an improved upscaling model framework, and eddy covariance flux measurements", REMOTE SENSING OF ENVIRONMENT., FEB 5, {2014}. Vol. {141}, pp. 90-104. |
| Abstract: More accurate estimation of the carbon dioxide flux depends on the improved scientific understanding of the terrestrial carbon cycle. Remote-sensing-based approaches to continental-scale estimation of net ecosystem exchange (NEE) have been developed but coarse spatial resolution is a source of errors. Here we demonstrate a satellite-based method of estimating NEE using Landsat TM/ETM + data and an upscaling framework. The upscaling framework contains flux-footprint climatology modeling, modified regression tree (MRT) analysis and image fusion. By scaling NEE measured at flux towers to landscape and regional scales, this satellite-based method can improve NEE estimation at high spatial-temporal resolution at the landscape scale relative to methods based on MODIS data with coarser spatial-temporal resolution. This method was applied to sixteen flux sites from the Canadian Carbon Program and AmeriFlux networks located in North America, covering forest, grass, and cropland biomes. Compared to a similar method using MODIS data, our estimation is more effective for diagnosing landscape NEE with the same temporal resolution and higher spatial resolution (30 m versus 1 km) (r(2) = 0.7548 vs. 0.5868, RMSE = 1.3979 vs. 1.7497 g C m-(2) day(-1), average error = 0.8950 vs. 1.0178 g C m(-2) day(-1), relative error = 0.47 vs. 0.54 for fused Landsat and MODIS imagery, respectively). We also compared the regional NEE estimations using Carbon Tracker, our method and eddy-covariance observations. This study demonstrates that the data-driven satellite-based NEE diagnosed model can be used to upscale eddy-flux observations to landscape scales with high spatial-temporal resolutions. (C) 2013 Elsevier Inc. All rights reserved. |
BibTeX:
@article{fu14a,
author = {Fu, Dongjie and Chen, Baozhang and Zhang, Huifang and Wang, Juan and Black, T. Andy and Amiro, Brian D. and Bohrer, Gil and Bolstad, Paul and Coulter, Richard and Rahman, Abdullah F. and Dunn, Allison and McCaughey, J. Harry and Meyers, Tilden and Verma, Shashi},
title = {Estimating landscape net ecosystem exchange at high spatial-temporal resolution based on Landsat data, an improved upscaling model framework, and eddy covariance flux measurements},
journal = {REMOTE SENSING OF ENVIRONMENT},
year = {2014},
volume = {141},
pages = {90--104},
doi = {10.1016/j.rse.2013.10.029}
}
|
| Gabrys J (2009), "Sink: the dirt of systems", Environment and Planning D: Society and Space. Vol. 27(4), pp. 666-681. |
BibTeX:
@article{gabrys09a,
author = {Gabrys, Jennifer},
title = {Sink: the dirt of systems},
journal = {Environment and Planning D: Society and Space},
year = {2009},
volume = {27},
number = {4},
pages = {666--681},
doi = {10.1068/d5708}
}
|
| Gahlot S, Shu S, Jain A and Roy SB (2017), "Estimating Trends and Variation of Net Biome Productivity in India for 1980--2012 Using a Land Surface Model", Geophysical Research Letters.
[BibTeX] |
BibTeX:
@article{gahlot17a,
author = {S Gahlot and S Shu and AK Jain and S Baidya Roy},
title = {Estimating Trends and Variation of Net Biome Productivity in India for 1980--2012 Using a Land Surface Model},
journal = {Geophysical Research Letters},
year = {2017}
}
|
| Gately CK, Hutyra LR, Wing IS and Brondfield MN ({2013}), "A Bottom up Approach to on-Road CO2 Emissions Estimates: Improved Spatial Accuracy and Applications for Regional Planning", ENVIRONMENTAL SCIENCE & TECHNOLOGY., MAR 5, {2013}. Vol. {47}({5}), pp. 2423-2430. |
| Abstract: On-road transportation is responsible for 28% of all U.S. fossil-fuel CO2 emissions. Mapping vehicle emissions at regional scales is challenging due to data limitations. Existing emission inventories use spatial proxies such as population and road density to downscale national or state-level data. Such procedures introduce errors where the proxy variables and actual emissions are weakly correlated, and limit analysis of the relationship between emissions and demographic trends at local scales. We develop an onroad emission inventory product for Massachusetts-based on roadway-level traffic data obtained from the Highway Performance Monitoring System (HPMS). We provide annual estimates of on-road CO2 emissions at a 1 x 1 km grid scale for the years 1980 through 2008. We compared our results with on-road emissions estimates from the Emissions Database for Global Atmospheric Research (EDGAR), with the Vulcan Product, and with estimates derived from state fuel consumption statistics reported by the Federal Highway Administration (FHWA). Our model differs from FHWA estimates by less than 8.5% on average, and is within 596 of Vulcan estimates. We found that EDGAR estimates systematically exceed FHWA by an average of 22.8br> Panel regression analysis of per-mile CO2 emissions on population density at the town scale shows a statistically significant correlation that varies systematically in sign and magnitude as population density increases. Population density has a positive correlation with per-mile CO2 emissions for densities below 2000 persons km(-2), above which increasing density correlates negatively with per-mile emissions. |
BibTeX:
@article{gately13a,
author = {Gately, Conor K. and Hutyra, Lucy R. and Wing, Ian Sue and Brondfield, Max N.},
title = {A Bottom up Approach to on-Road CO2 Emissions Estimates: Improved Spatial Accuracy and Applications for Regional Planning},
journal = {ENVIRONMENTAL SCIENCE & TECHNOLOGY},
year = {2013},
volume = {47},
number = {5},
pages = {2423--2430},
doi = {10.1021/es304238v}
}
|
| Gately CK (2016), "Emissions from mobile sources: Improved understanding of the drivers of emissions and their spatial patterns". Thesis at: Boston University. |
BibTeX:
@phdthesis{gately16a,
author = {Gately, Conor Kennedy},
title = {Emissions from mobile sources: Improved understanding of the drivers of emissions and their spatial patterns},
school = {Boston University},
year = {2016},
url = {http://search.proquest.com/openview/660fb3eced8341af00fe6f17a1aee2f4/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Gately CK and Hutyra LR ({2017}), "Large Uncertainties in Urban-Scale Carbon Emissions", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 27, {2017}. Vol. {122}({20}), pp. 11242-11260. |
| Abstract: Accurate estimates of fossil fuel carbon dioxide (FFCO2) emissions are a critical component of local, regional, and global climate agreements. Current global inventories of FFCO2 emissions do not directly quantify emissions at local scales; instead, spatial proxies like population density, nighttime lights, and power plant databases are used to downscale emissions from national totals. We have developed a high-resolution (hourly, 1 km(2)) bottom-up Anthropogenic Carbon Emissions System (ACES) for FFCO2, based on local activity data for the year 2011 across the northeastern U.S. We compare ACES with three widely used global inventories, finding significant differences at regional (20 and city scales (50-250. At a spatial resolution of 0.1 degrees, inventories differ by over 100% for half of the grid cells in the domain, with the largest differences in urban areas and oil and gas production regions. Given recent U.S. federal policy pull backs regarding greenhouse gas emissions reductions, inventories like ACES are crucial for U.S. actions, as the impetus for climate leadership has shifted to city and state governments. The development of a robust carbon monitoring system to track carbon fluxes is critical for emissions benchmarking and verification. We show that existing downscaled inventories are not suitable for urban emissions monitoring, as they do not consider important local activity patterns. The ACES methodology is designed for easy updating, making it suitable for emissions monitoring under most city, regional, and state greenhouse gas mitigation initiatives, in particular, for the small-and medium-sized cities that lack the resources to regularly perform their own bottom-up emissions inventories. |
BibTeX:
@article{gately17a,
author = {Gately, C. K. and Hutyra, L. R.},
title = {Large Uncertainties in Urban-Scale Carbon Emissions},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2017},
volume = {122},
number = {20},
pages = {11242--11260},
doi = {10.1002/2017JD027359}
}
|
| Geibel MC (2011), "Measurement of climate-relevant trace gases via infrared spectroscopy". Thesis at: Friedrich-Schiller-Universitat Jena. |
BibTeX:
@phdthesis{geibel11a,
author = {Geibel, Marc Christoph},
title = {Measurement of climate-relevant trace gases via infrared spectroscopy},
school = {Friedrich-Schiller-Universitat Jena},
year = {2011},
url = {https://d-nb.info/1016620160/34}
}
|
| Gennaretti F, Gea-Izquierdo G, Boucher E, Berninger F, Arseneault D and Guiot J ({2017}), "Ecophysiological modeling of photosynthesis and carbon allocation to the tree stem in the boreal forest", BIOGEOSCIENCES., NOV 6, {2017}. Vol. {14}({21}), pp. 4851-4866. |
| Abstract: A better understanding of the coupling between photosynthesis and carbon allocation in the boreal forest, together with its associated environmental factors and mechanistic rules, is crucial to accurately predict boreal forest carbon stocks and fluxes, which are significant components of the global carbon budget. Here, we adapted the MAIDEN ecophysiological forest model to consider important processes for boreal tree species, such as nonlinear acclimation of photosynthesis to temperature changes, canopy development as a function of previous-year climate variables influencing bud formation and the temperature dependence of carbon partition in summer. We tested these modifications in the eastern Canadian taiga using black spruce (Picea mariana (Mill.) B.S.P.) gross primary production and ring width data. MAIDEN explains 90% of the observed daily gross primary production variability, 73% of the annual ring width variability and 20-30% of its high-frequency component (i.e., when decadal trends are removed). The positive effect on stem growth due to climate warming over the last several decades is well captured by the model. In addition, we illustrate how we improve the model with each introduced model adaptation and compare the model results with those of linear response functions. Our results demonstrate that MAIDEN simulates robust relationships with the most important climate variables (those detected by classical response-function analysis) and is a powerful tool for understanding how environmental factors interact with black spruce ecophysiol-ogy to influence present-day and future boreal forest carbon fluxes. |
BibTeX:
@article{gennaretti17a,
author = {Gennaretti, Fabio and Gea-Izquierdo, Guillermo and Boucher, Etienne and Berninger, Frank and Arseneault, Dominique and Guiot, Joel},
title = {Ecophysiological modeling of photosynthesis and carbon allocation to the tree stem in the boreal forest},
journal = {BIOGEOSCIENCES},
year = {2017},
volume = {14},
number = {21},
pages = {4851--4866},
doi = {10.5194/bg-14-4851-2017}
}
|
| Georgoulias AK, Kourtidis KA, Buchwitz M, Schneising O and Burrows JP ({2011}), "A case study on the application of SCIAMACHY satellite methane measurements for regional studies: the Greater Area of the Eastern Mediterranean", INTERNATIONAL JOURNAL OF REMOTE SENSING. Vol. {32}({3}), pp. 787-813. |
| Abstract: Many studies have focused on geological formations, such as mud volcanoes, which abound in the Greater Area of the Eastern Mediterranean (GAEM; 25 degrees N-50 degrees N, 5 degrees E-55 degrees E). This geological source is thought to provide a significant portion of the global methane (CH4) emissions. However, studies in the GAEM have focused on specific locations rather than extensive areas, which has led to a gap in our understanding of the spatial and temporal variability of CH4 atmospheric mixing ratios. Here, we present characteristics of methane loading over land in the GAEM using dry air columnar data (XCH4) retrieved from SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) satellite measurements with the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS) version 1.0 algorithm. We defined methane annual, seasonal and monthly spatial patterns over the area using 2003 and 2004 measurements. The annual mean XCH4 levels over the study area were estimated to be 1761 +/- 27 ppb for 2003 and 1758 +/- 26 ppb for 2004. A seasonal variability with a summer-autumn peak was observed for both 2003 and 2004, August being the month with the highest methane concentrations. The northeastern part of the area exhibits the highest XCH4 values while the high elevation regions defined by the triangle of eastern Turkey, the Persian Gulf and the Caspian Sea and the region of the eastern coast of the Red Sea exhibit the lowest levels. A latitudinal gradient was observed for the area during 2003 and 2004. A comparison of measured XCH4 levels above two of the world's most renowned mud volcano regions situated in the GAEM with anticipated methane columnar concentrations as modelled for eruption cases shows that no mud volcano eruptions were observed from SCIAMACHY during 2003 or 2004. |
BibTeX:
@article{georgoulias11a,
author = {Georgoulias, A. K. and Kourtidis, K. A. and Buchwitz, M. and Schneising, O. and Burrows, J. P.},
title = {A case study on the application of SCIAMACHY satellite methane measurements for regional studies: the Greater Area of the Eastern Mediterranean},
journal = {INTERNATIONAL JOURNAL OF REMOTE SENSING},
year = {2011},
volume = {32},
number = {3},
pages = {787--813},
doi = {10.1080/01431161.2010.517791}
}
|
| Gerbig C, Dolman AJ and Heimann M ({2009}), "On observational and modelling strategies targeted at regional carbon exchange over continents", BIOGEOSCIENCES. Vol. {6}({10}), pp. 1949-1959. |
| Abstract: Estimating carbon exchange at regional scales is paramount to understanding feedbacks between climate and the carbon cycle, but also to verifying climate change mitigation such as emission reductions and strategies compensating for emissions such as carbon sequestration. This paper discusses evidence for a number of important shortcomings of current generation modelling frameworks designed to provide regional scale budgets from atmospheric observations. Current top-down and bottom-up approaches targeted at deriving consistent regional scale carbon exchange estimates for biospheric and anthropogenic sources and sinks are hampered by a number of issues: we show that top-down constraints using point measurements made from tall towers, although sensitive to larger spatial scales, are however influenced by local areas much more strongly than previously thought. On the other hand, classical bottom-up approaches using process information collected at the local scale, such as from eddy covariance data, need up-scaling and validation on larger scales. We therefore argue for a combination of both approaches, implicitly providing the important local scale information for the top-down constraint, and providing the atmospheric constraint for up-scaling of flux measurements. Combining these data streams necessitates quantifying their respective representation errors, which are discussed. The impact of these findings on future network design is highlighted, and some recommendations are given. |
BibTeX:
@article{gerbig09a,
author = {Gerbig, C. and Dolman, A. J. and Heimann, M.},
title = {On observational and modelling strategies targeted at regional carbon exchange over continents},
journal = {BIOGEOSCIENCES},
year = {2009},
volume = {6},
number = {10},
pages = {1949--1959},
doi = {10.5194/bg-6-1949-2009}
}
|
| Geyer NM (2015), "Time-filtered inverse modeling of land-atmosphere carbon exchange". Thesis at: Colorado State University. |
BibTeX:
@phdthesis{geyer15a,
author = {Geyer, Nicholas M},
title = {Time-filtered inverse modeling of land-atmosphere carbon exchange},
school = {Colorado State University},
year = {2015},
url = {http://search.proquest.com/openview/e038a9c458ca8f6d6358546eff579bf6/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Gilmanov TG, Aires L, Barcza Z, Baron VS, Belelli L, Beringer J, Billesbach D, Bonal D, Bradford J, Ceschia E, Cook D, Corradi C, Frank A, Gianelle D, Gimeno C, Gruenwald T, Guo H, Hanan N, Haszpra L, Heilman J, Jacobs A, Jones MB, Johnson DA, Kiely G, Li S, Magliulo V, Moors E, Nagy Z, Nasyrov M, Owensby C, Pinter K, Pio C, Reichstein M, Sanz MJ, Scott R, Soussana JF, Stoy PC, Svejcar T, Tuba Z and Zhou G ({2010}), "Productivity, Respiration, and Light-Response Parameters of World Grassland and Agroecosystems Derived From Flux-Tower Measurements", RANGELAND ECOLOGY & MANAGEMENT., JAN, {2010}. Vol. {63}({1}), pp. 16-39. |
| Abstract: Grasslands and agroecosystems occupy one-third of the terrestrial area, but their contribution to the global carbon cycle remains uncertain. We used a set of 316 site-years of CO(2) exchange measurements to quantify gross primary productivity, respiration, and light-response parameters of grasslands, shrublands/savanna, wetlands, and cropland ecosystems worldwide. We analyzed data from 72 global flux-tower sites partitioned into gross photosynthesis and ecosystem respiration with the use of the light-response method (Gilmanov, T. G., D. A. Johnson, and N. Z. Saliendra. 2003. Growing season CO(2) fluxes in a sagebrushsteppe ecosystem in Idaho: Bowen ratio/energy balance measurements and modeling. Basic and Applied Ecology 4:167-183) from the RANGEFLUX and WORLDGRASSAGRIFLUX data sets supplemented by 46 sites from the FLUXNET La Thuile data set partitioned with the use of the temperature-response method (Reichstein, M., E. Falge, D. Baldocchi, D. Papale, R. Valentini, M. Aubinet, P. Berbigier, C. Bernhofer, N. Buchmann, M. Falk, T. Gilmanov, A. Granier, T. Grunwald, K. Havrankova, D. Janous, A. Knohl, T. Laurela, A. Lohila, D. Loustau, G. Matteucci, T. Meyers, F. Miglietta, J.M. Ourcival, D. Perrin, J. Pumpanen, S. Rambal, E. Rotenberg, M. Sanz, J. Tenhunen, G. Seufert, F. Vaccari, T. Vesala, and D. Yakir. 2005. On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm. Global Change Biology 11: 1.424-1439). Maximum values of the quantum yield (alpha = 75 mmol.mol(-1)), photosynthetic capacity (A(max) = 3.4 mg CO(2) . m(-2).s-1), gross photosynthesis (P(g,max) = 1.16 g CO(2) . m(-2).d(-1)), and ecological light-use efficiency (epsilon(ecol) = 59 mmol . mol(-1)) of managed grasslands and high-production croplands exceeded those of most forest ecosystems, indicating the potential of nonforest ecosystems for uptake of atmospheric CO(2). Maximum values of gross primary production (8 600 g CO(2) . m(-2).yr(-1)), total ecosystem respiration (7 900 g CO(2) . m(-2).yr(-1)), and net CO(2) exchange (2 400 g CO(2) . m(-2).yr(-1)) were observed for intensively managed grasslands and high-yield crops, and are comparable to or higher than those for forest ecosystems, excluding some tropical forests. On average, 80% of the nonforest sites were apparent sinks for atmospheric CO(2), with mean net uptake of 700 g CO(2) . m(-2).yr(-1) for intensive grasslands and 933 g CO(2) . m(-2).d(-1) for croplands. However, part of these apparent sinks is accumulated in crops and forage, which are carbon pools that are harvested, transported, and decomposed off site. Therefore, although agricultural fields may be predominantly sinks for atmospheric CO(2), this does not imply that they are necessarily increasing their carbon stock. |
BibTeX:
@article{gilmanov10a,
author = {Gilmanov, Tagir G. and Aires, L. and Barcza, Z. and Baron, V. S. and Belelli, L. and Beringer, J. and Billesbach, D. and Bonal, D. and Bradford, J. and Ceschia, E. and Cook, D. and Corradi, C. and Frank, A. and Gianelle, D. and Gimeno, C. and Gruenwald, T. and Guo, Haiqiang and Hanan, N. and Haszpra, L. and Heilman, J. and Jacobs, A. and Jones, M. B. and Johnson, D. A. and Kiely, G. and Li, Shenggong and Magliulo, V. and Moors, E. and Nagy, Z. and Nasyrov, M. and Owensby, C. and Pinter, K. and Pio, C. and Reichstein, M. and Sanz, M. J. and Scott, R. and Soussana, J. F. and Stoy, P. C. and Svejcar, T. and Tuba, Z. and Zhou, Guangsheng},
title = {Productivity, Respiration, and Light-Response Parameters of World Grassland and Agroecosystems Derived From Flux-Tower Measurements},
journal = {RANGELAND ECOLOGY & MANAGEMENT},
year = {2010},
volume = {63},
number = {1},
pages = {16--39},
doi = {10.2111/REM-D-09-00072.1}
}
|
| Glaser R, Castello-Blindt PO and Yin J (2013), "Biomimetic Approaches to Reversible CO2 Capture from Air. N-Methylcarbaminic Acid Formation in Rubsico-Inspired Models", New and Future Developments in Catalysis: Activation of Carbon Dioxide. , pp. 501-534. |
BibTeX:
@article{glaser13a,
author = {Glaser, Rainer and Castello-Blindt, Paula O and Yin, Jian},
title = {Biomimetic Approaches to Reversible CO2 Capture from Air. N-Methylcarbaminic Acid Formation in Rubsico-Inspired Models},
journal = {New and Future Developments in Catalysis: Activation of Carbon Dioxide},
year = {2013},
pages = {501--534},
url = {https://faculty.missouri.edu/ glaserr/vitpub/NMCA_Chapter.pdf}
}
|
| Gockede M, Michalak AM, Vickers D, Turner DP and Law BE ({2010}), "Atmospheric inverse modeling to constrain regional-scale CO2 budgets at high spatial and temporal resolution", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., AUG 14, {2010}. Vol. {115} |
| Abstract: We present an inverse modeling framework designed to constrain CO2 budgets at regional scales. The approach captures atmospheric transport processes in high spatiotemporal resolution by coupling a mesoscale model with Lagrangian Stochastic backward trajectories. Terrestrial biosphere CO2 emissions are generated through a simple diagnostic flux model that splits the net ecosystem exchange into its major components of gross primary productivity and autotrophic and heterotrophic respirations. The modeling framework assimilates state-of-the-art data sets for advected background CO2 and anthropogenic fossil fuel emissions as well as highly resolved remote sensing products. We introduce a Bayesian inversion setup, optimizing a posteriori flux base rates for surface types that are defined through remote sensing information. This strategy significantly reduces the number of parameters to be optimized compared with solving fluxes for each individual grid cell, thus permitting description of the surface in a very high resolution. The model is tested using CO2 concentrations measured in the fall and winter of 2006 at two AmeriFlux sites in Oregon. Because this database does not cover a full seasonal cycle, we focus on conducting model sensitivity tests rather than producing quantitative CO2 flux estimates. Sensitivity tests on the influence of spatial and temporal resolution indicate that optimum results can be obtained using 4 h time steps and grid sizes of 6 km or less. Further tests demonstrate the importance of dividing biome types by ecoregions to capture their different biogeochemical responses to external forcings across climatic gradients. Detailed stand age information was shown to have a positive effect on model performance. |
BibTeX:
@article{gockede10a,
author = {Gockede, Mathias and Michalak, Anna M. and Vickers, Dean and Turner, David P. and Law, Beverly E.},
title = {Atmospheric inverse modeling to constrain regional-scale CO2 budgets at high spatial and temporal resolution},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2010},
volume = {115},
doi = {10.1029/2009JD012257}
}
|
| Gockede M, Turner DP, Michalak AM, Vickers D and Law BE ({2010}), "Sensitivity of a subregional scale atmospheric inverse CO2 modeling framework to boundary conditions", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 23, {2010}. Vol. {115} |
| Abstract: We present an atmospheric inverse modeling framework to constrain terrestrial biosphere CO2 exchange processes at subregional scales. The model is operated at very high spatial and temporal resolution, using the state of Oregon in the northwestern United States as the model domain. The modeling framework includes mesoscale atmospheric simulations coupled to Lagrangian transport, a biosphere flux model that considers, e.g., the effects of drought stress and disturbance on photosynthesis and respiration CO2 fluxes, and a Bayesian optimization approach. This study focuses on the impact of uncertainties in advected background mixing ratios and fossil fuel emissions on simulated flux fields, both taken from external data sets. We found the simulations to be highly sensitive to systematic changes in advected background CO2, while shifts in fossil fuel emissions played a minor role. Correcting for offsets in the background mixing ratios shifted annual CO2 budgets by about 47% and improved the correspondence with the output produced by bottom-up modeling frameworks. Inversion results were robust against shifts in fossil fuel emissions, which is likely a consequence of relatively low emission rates in Oregon. |
BibTeX:
@article{gockede10b,
author = {Gockede, Mathias and Turner, David P. and Michalak, Anna M. and Vickers, Dean and Law, Beverly E.},
title = {Sensitivity of a subregional scale atmospheric inverse CO2 modeling framework to boundary conditions},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2010},
volume = {115},
doi = {10.1029/2010JD014443}
}
|
| Gomes D, Vicente LE, Silva R, Paula S, Maçorano RP, Victoria D and Batistella M (2013), "Uso de dados MODIS e AIRS para obten¸ cão de parâmetros de corre¸ cão atmosférica", Simpósio Brasileiro de Sensoriamento Remoto. Vol. 16, pp. 8019-8026. |
BibTeX:
@article{gomes13a,
author = {Gomes, Daniel and Vicente, Luiz Eduardo and Silva, RFB and Paula, SC and Maçorano, Renan Pfister and Victoria, DC and Batistella, Mateus},
title = {Uso de dados MODIS e AIRS para obten¸ cão de parâmetros de corre¸ cão atmosférica},
journal = {Simpósio Brasileiro de Sensoriamento Remoto},
year = {2013},
volume = {16},
pages = {8019--8026},
url = {https://ainfo.cnptia.embrapa.br/digital/bitstream/item/82762/1/DanielSBSR.pdf}
}
|
| Gourdji SM, Hirsch AI, Mueller KL, Yadav V, Andrews AE and Michalak AM ({2010}), "Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({13}), pp. 6151-6167. |
| Abstract: A series of synthetic data experiments is performed to investigate the ability of a regional atmospheric inversion to estimate grid-scale CO2 fluxes during the growing season over North America. The inversions are performed within a geostatistical framework without the use of any prior flux estimates or auxiliary variables, in order to focus on the atmospheric constraint provided by the nine towers collecting continuous, calibrated CO2 measurements in 2004. Using synthetic measurements and their associated concentration footprints, flux and model-data mismatch covariance parameters are first optimized, and then fluxes and their uncertainties are estimated at three different temporal resolutions. These temporal resolutions, which include a four-day average, a four-day-average diurnal cycle with 3-hourly increments, and 3-hourly fluxes, are chosen to help assess the impact of temporal aggregation errors on the estimated fluxes and covariance parameters. Estimating fluxes at a temporal resolution that can adjust the diurnal variability is found to be critical both for recovering covariance parameters directly from the atmospheric data, and for inferring accurate ecoregion-scale fluxes. Accounting for both spatial and temporal a priori covariance in the flux distribution is also found to be necessary for recovering accurate a posteriori uncertainty bounds on the estimated fluxes. Overall, the results suggest that even a fairly sparse network of 9 towers collecting continuous CO2 measurements across the continent, used with no auxiliary information or prior estimates of the flux distribution in time or space, can be used to infer relatively accurate monthly ecoregion scale CO2 surface fluxes over North America within estimated uncertainty bounds. Simulated random transport error is shown to decrease the quality of flux estimates in under-constrained areas at the ecoregion scale, although the uncertainty bounds remain realistic. While these synthetic data inversions do not consider all potential issues associated with using actual measurement data, e.g. systematic transport errors or problems with the boundary conditions, they help to highlight the impact of inversion setup choices, and help to provide a baseline set of CO2 fluxes for comparison with estimates from future real-data inversions. |
BibTeX:
@article{gourdji10a,
author = {Gourdji, S. M. and Hirsch, A. I. and Mueller, K. L. and Yadav, V. and Andrews, A. E. and Michalak, A. M.},
title = {Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2010},
volume = {10},
number = {13},
pages = {6151--6167},
doi = {10.5194/acp-10-6151-2010}
}
|
| Gourdji SM (2011), "Improved estimates of regional-scale land-atmosphere Carbon dioxide exchange using geostatistical atmospheric inverse models". Thesis at: University of Michigan. |
BibTeX:
@phdthesis{gourdji11a,
author = {Gourdji, Sharon Muzli},
title = {Improved estimates of regional-scale land-atmosphere Carbon dioxide exchange using geostatistical atmospheric inverse models},
school = {University of Michigan},
year = {2011},
url = {http://search.proquest.com/openview/331603ec402236ba8e528454f7373a97/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Gourdji SM, Mueller KL, Yadav V, Huntzinger DN, Andrews AE, Trudeau M, Petron G, Nehrkorn T, Eluszkiewicz J, Henderson J, Wen D, Lin J, Fischer M, Sweeney C and Michalak AM ({2012}), "North American CO2 exchange: inter-comparison of modeled estimates with results from a fine-scale atmospheric inversion", BIOGEOSCIENCES. Vol. {9}({1}), pp. 457-475. |
| Abstract: Atmospheric inversion models have the potential to quantify CO2 fluxes at regional, sub-continental scales by taking advantage of near-surface CO2 mixing ratio observations collected in areas with high flux variability. This study presents results from a series of regional geostatistical inverse models (GIM) over North America for 2004, and uses them as the basis for an inter-comparison to other inversion studies and estimates from biospheric models collected through the North American Carbon Program Regional and Continental Interim Synthesis. Because the GIM approach does not require explicit prior flux estimates and resolves fluxes at fine spatiotemporal scales (i.e. 1 degrees x 1 degrees, 3-hourly in this study), it avoids temporal and spatial aggregation errors and allows for the recovery of realistic spatial patterns from the atmospheric data relative to previous inversion studies. Results from a GIM inversion using only available atmospheric observations and a fine-scale fossil fuel inventory were used to confirm the quality of the inventory and inversion setup. An inversion additionally including auxiliary variables from the North American Regional Reanalysis found inferred relationships with flux consistent with physiological understanding of the biospheric carbon cycle. Comparison of GIM results with bottom-up biospheric models showed stronger agreement during the growing relative to the dormant season, in part because most of the biospheric models do not fully represent agricultural land-management practices and the fate of both residual biomass and harvested products. Comparison to earlier inversion studies pointed to aggregation errors as a likely source of bias in previous subcontinental scale flux estimates, particularly for inversions that adjust fluxes at the coarsest scales and use atmospheric observations averaged over long periods. Finally, whereas the continental CO2 boundary conditions used in the GIM inversions have a minor impact on spatial patterns, they have a substantial impact on the continental carbon budget, with a difference of 0.8 PgC yr(-1) in the total continental flux resulting from the use of two plausible sets of boundary CO2 mixing ratios. Overall, this inter-comparison study helps to assess the state of the science in estimating regional-scale CO2 fluxes, while pointing towards the path forward for improvements in future top-down and bottom-up modeling efforts. |
BibTeX:
@article{gourdji12a,
author = {Gourdji, S. M. and Mueller, K. L. and Yadav, V. and Huntzinger, D. N. and Andrews, A. E. and Trudeau, M. and Petron, G. and Nehrkorn, T. and Eluszkiewicz, J. and Henderson, J. and Wen, D. and Lin, J. and Fischer, M. and Sweeney, C. and Michalak, A. M.},
title = {North American CO2 exchange: inter-comparison of modeled estimates with results from a fine-scale atmospheric inversion},
journal = {BIOGEOSCIENCES},
year = {2012},
volume = {9},
number = {1},
pages = {457--475},
doi = {10.5194/bg-9-457-2012}
}
|
| Graven HD and Gruber N ({2011}), "Continental-scale enrichment of atmospheric (CO2)-C-14 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({23}), pp. 12339-12349. |
| Abstract: The C-14-free fossil carbon added to atmospheric CO2 by combustion dilutes the atmospheric C-14/C ratio (Delta C-14), potentially providing a means to verify fossil CO2 emissions calculated using economic inventories. However, sources of C-14 from nuclear power generation and spent fuel reprocessing can counteract this dilution and may bias C-14/C-based estimates of fossil fuel-derived CO2 if these nuclear influences are not correctly accounted for. Previous studies have examined nuclear influences on local scales, but the potential for continental-scale influences on Delta C-14 has not yet been explored. We estimate annual C-14 emissions from each nuclear site in the world and conduct an Eulerian transport modeling study to investigate the continental-scale, steady-state gradients of Delta C-14 caused by nuclear activities and fossil fuel combustion. Over large regions of Europe, North America and East Asia, nuclear enrichment may offset at least 20% of the fossil fuel dilution in Delta C-14, corresponding to potential biases of more than -0.25 ppm in the CO2 attributed to fossil fuel emissions, larger than the bias from plant and soil respiration in some areas. Model grid cells including high C-14-release reactors or fuel reprocessing sites showed much larger nuclear enrichment, despite the coarse model resolution of 1.8 degrees x 1.8 degrees. The recent growth of nuclear C-14 emissions increased the potential nuclear bias over 1985-2005, suggesting that changing nuclear activities may complicate the use of Delta C-14 observations to identify trends in fossil fuel emissions. The magnitude of the potential nu-clear bias is largely independent of the choice of reference station in the context of continental-scale Eulerian transport and inversion studies, but could potentially be reduced by an appropriate choice of reference station in the context of local-scale assessments. |
BibTeX:
@article{graven11a,
author = {Graven, H. D. and Gruber, N.},
title = {Continental-scale enrichment of atmospheric (CO2)-C-14 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2011},
volume = {11},
number = {23},
pages = {12339--12349},
doi = {10.5194/acp-11-12339-2011}
}
|
| Guan K (2013), "Hydrological variability on vegetation seasonality, productivity and composition in tropical ecosystems of Africa". Thesis at: Princeton University. |
BibTeX:
@phdthesis{guan13a,
author = {Guan, Kaiyu},
title = {Hydrological variability on vegetation seasonality, productivity and composition in tropical ecosystems of Africa},
school = {Princeton University},
year = {2013},
url = {http://search.proquest.com/openview/bdb3c89d79b0a9555cf6e3419d6a81d0/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Guan K, Medvigy D, Wood EF, Caylor KK, Li S and Jeong S-J ({2014}), "Deriving Vegetation Phenological Time and Trajectory Information Over Africa Using SEVIRI Daily LAI", IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING., FEB, {2014}. Vol. {52}({2}), pp. 1113-1130. |
| Abstract: Vegetation phenology is closely connected to the terrestrial carbon budget, and interacts with the atmosphere through surface water and energy exchange. A comprehensive and detailed characterization of the spatio-temporal pattern of vegetation phenology can be used to improve the understanding of interactions between vegetation and climate in Africa. This research provides an approach to derive phenology time and trajectory parameters by optimally fitting a double-logistic curve to daily remotely sensed leaf area index (LAI) from the spinning enhanced visible and infrared imager. The proposed algorithm can reconstruct the temporal LAI trajectory based on the optimized parameters with a high accuracy, and provides user-defined phenological timing information (e.g., start/end of the growing season) and trajectory information (e.g., leaf emergence/senescence rate and length) using these fitted parameters. Both single and double growing-season cases have been considered with a spatial classification scheme implemented over Africa. The newly derived vegetation phenology of Africa exhibits emerging spatial patterns in growing season length, asymmetric green-up and green-off length/rate, and distinctive phenological features of cropland and natural vegetation. This approach has the potential to be applied globally, and the derived vegetation phenological information will improve dynamic vegetation modeling and climate prediction. |
BibTeX:
@article{guan14a,
author = {Guan, Kaiyu and Medvigy, David and Wood, Eric F. and Caylor, Kelly K. and Li, Shi and Jeong, Su-Jong},
title = {Deriving Vegetation Phenological Time and Trajectory Information Over Africa Using SEVIRI Daily LAI},
journal = {IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING},
year = {2014},
volume = {52},
number = {2},
pages = {1113--1130},
doi = {10.1109/TGRS.2013.2247611}
}
|
| Guerlet S, Butz A, Schepers D, Basu S, Hasekamp OP, Kuze A, Yokota T, Blavier JF, Deutscher NM, Griffith DWT, Hase F, Kyro E, Morino I, Sherlock V, Sussmann R, Galli A and Aben I ({2013}), "Impact of aerosol and thin cirrus on retrieving and validating XCO2 from GOSAT shortwave infrared measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 27, {2013}. Vol. {118}({10}), pp. 4887-4905. |
| Abstract: Inadequate treatment of aerosol scattering can be a significant source of error when retrieving column-averaged dry-air mole fractions of CO2 (XCO2) from space-based measurements of backscattered solar shortwave radiation. We have developed a retrieval algorithm, RemoTeC, that retrieves three aerosol parameters (amount, size, and height) simultaneously with XCO2. Here we evaluate the ability of RemoTeC to account for light path modifications by clouds, subvisual cirrus, and aerosols when retrieving XCO2 from Greenhouse Gases Observing Satellite (GOSAT) Thermal and Near-infrared Sensor for carbon Observation (TANSO)-Fourier Transform Spectrometer (FTS) measurements. We first evaluate a cloud filter based on measurements from the Cloud and Aerosol Imager and a cirrus filter that uses radiances measured by TANSO-FTS in the 2micron spectral region, with strong water absorption. For the cloud-screened scenes, we then evaluate errors due to aerosols. We find that RemoTeC is well capable of accounting for scattering by aerosols for values of aerosol optical thickness at 750nm up to 0.25. While no significant correlation of errors is found with albedo, correlations are found with retrieved aerosol parameters. To further improve the XCO2 accuracy, we propose and evaluate a bias correction scheme. Measurements from 12 ground-based stations of the Total Carbon Column Observing Network (TCCON) are used as a reference in this study. We show that spatial colocation criteria may be relaxed using additional constraints based on modeled XCO2 gradients, to increase the size and diversity of validation data and provide a more robust evaluation of GOSAT retrievals. Global-scale validation of satellite data remains challenging and would be improved by increasing TCCON coverage. |
BibTeX:
@article{guerlet13a,
author = {Guerlet, S. and Butz, A. and Schepers, D. and Basu, S. and Hasekamp, O. P. and Kuze, A. and Yokota, T. and Blavier, J. -F. and Deutscher, N. M. and Griffith, D. W. T. and Hase, F. and Kyro, E. and Morino, I. and Sherlock, V. and Sussmann, R. and Galli, A. and Aben, I.},
title = {Impact of aerosol and thin cirrus on retrieving and validating XCO2 from GOSAT shortwave infrared measurements},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2013},
volume = {118},
number = {10},
pages = {4887--4905},
doi = {10.1002/jgrd.50332}
}
|
| Halloran PR ({2012}), "Does atmospheric CO2 seasonality play an important role in governing the air-sea flux of CO2?", BIOGEOSCIENCES. Vol. {9}({6}), pp. 2311-2323. |
| Abstract: The amplitude, phase, and form of the seasonal cycle of atmospheric CO2 concentrations varies on many time and space scales (Peters et al., 2007). Intra-annual CO2 variation is primarily driven by seasonal uptake and release of CO2 by the terrestrial biosphere (Machta et al., 1977; Buchwitz et al., 2007), with a small (Cadule et al., 2010; Heimann et al., 1998), but potentially changing (Gorgues et al., 2010) contribution from the ocean. Variability in the magnitude, spatial distribution, and seasonal drivers of terrestrial net primary productivity (NPP) will be induced by, amongst other factors, anthropogenic CO2 release (Keeling et al., 1996), land-use change (Zimov et al., 1999) and planetary orbital variability, and will lead to changes in CO2atm seasonality. Despite CO2atm seasonality being a dynamic and prominent feature of the Earth System, its potential to drive changes in the air-sea flux of CO2 has not previously (to the best of my knowledge) been explored. It is important that we investigate the impact of CO2atm seasonality change, and the potential for carbon-cycle feedbacks to operate through the modification of the CO2atm seasonal cycle, because the decision had been made to prescribe CO2atm concentrations (rather than emissions) within model simulations for the fifth IPCC climate assessment (Taylor et al., 2009). In this study I undertake ocean-model simulations within which different magnitude CO2atm seasonal cycles are prescribed. These simulations allow me to examine the effect of a change in CO2atm seasonal cycle magnitude on the air-sea CO2 flux. I then use an offline model to isolate the drivers of the identified air-sea CO2 flux change, and propose mechanisms by which this change may come about. Three mechanisms are identified by which co-variability of the seasonal cycles in atmospheric CO2 concentration, and seasonality in sea-ice extent, wind-speed and ocean temperature, could potentially lead to changes in the air-sea flux of CO2 at mid-to-high latitudes. The sea-ice driven mechanism responds to an increase in CO2atm seasonality by pumping CO2 into the ocean, the wind-speed and solubility-driven mechanisms, by releasing CO2 from the ocean (in a relative sense). The relative importance of the mechanisms will be determined by, amongst other variables, the seasonal extent of sea-ice. To capture the described feedbacks within earth system models, CO2atm concentrations must be allowed to evolve freely, forced only by anthropogenic emissions rather than prescribed CO2atm concentrations; however, time-integrated ocean simulations imply that the cumulative net air-sea flux could be at most equivalent to a few ppm CO2atm. The findings presented here suggest that, at least under pre-industrial conditions, the prescription of CO2atm concentrations rather than emissions within simulations will have little impact on the marine anthropogenic CO2 sink. |
BibTeX:
@article{halloran12a,
author = {Halloran, P. R.},
title = {Does atmospheric CO2 seasonality play an important role in governing the air-sea flux of CO2?},
journal = {BIOGEOSCIENCES},
year = {2012},
volume = {9},
number = {6},
pages = {2311--2323},
doi = {10.5194/bg-9-2311-2012}
}
|
| Haszpra L, Ramonet M, Schmidt M, Barcza Z, Patkai Z, Tarczay K, Yver C, Tarniewicz J and Ciais P ({2012}), "Variation of CO2 mole fraction in the lower free troposphere, in the boundary layer and at the surface", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({18}), pp. 8865-8875. |
| Abstract: Eight years of occasional flask air sampling and 3 years of frequent in situ measurements of carbon dioxide (CO2) vertical profiles on board of a small aircraft, over a tall tower greenhouse gases monitoring site in Hungary are used for the analysis of the variations of vertical profile of CO2 mole fraction. Using the airborne vertical profiles and the measurements along the 115 m tall tower it is shown that the measurements at the top of the tower estimate the mean boundary layer CO2 mole fraction during the mid-afternoon fairly well, with an underestimation of 0.27-0.85 mu mol mol(-1) in summer, and an overestimation of 0.66-1.83 mu mol mol(-1) in winter. The seasonal cycle of CO2 mole fraction is damped with elevation. While the amplitude of the seasonal cycle is 28.5 mu mol mol(-1) at 10 m above the ground, it is only 10.7 mu mol mol(-1) in the layer of 2500-3000 m corresponding to the lower free atmosphere above the well-mixed boundary layer. The maximum mole fraction in the layer of 2500-3000 m can be observed around 25 March on average, two weeks ahead of that of the marine boundary layer reference (GLOBALVIEW). By contrast, close to the ground, the maximum CO2 mole fraction is observed late December, early January. The specific seasonal behavior is attributed to the climatology of vertical mixing of the atmosphere in the Carpathian Basin. |
BibTeX:
@article{haszpra12a,
author = {Haszpra, L. and Ramonet, M. and Schmidt, M. and Barcza, Z. and Patkai, Zs and Tarczay, K. and Yver, C. and Tarniewicz, J. and Ciais, P.},
title = {Variation of CO2 mole fraction in the lower free troposphere, in the boundary layer and at the surface},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2012},
volume = {12},
number = {18},
pages = {8865--8875},
doi = {10.5194/acp-12-8865-2012}
}
|
| Hayashida S, Ono A, Yoshizaki S, Frankenberg C, Takeuchi W and Yan X ({2013}), "Methane concentrations over Monsoon Asia as observed by SCIAMACHY: Signals of methane emission from rice cultivation", REMOTE SENSING OF ENVIRONMENT., DEC, {2013}. Vol. {139}, pp. 246-256. |
| Abstract: We have analyzed the column-averaged CH4 concentration (xCH(4)) using scanning imaging absorption spectrometer for atmospheric chartography (SCIAMACHY) and compared the data with the bottom-up emission inventory data sets and other satellite-derived indices such as the land-surface water coverge (LSWC) and the normalized difference vegetation index (NDVI). The geographical distribution of high CH4 values corresponds to strong emissions from regions where rice is cultivated, as indicated in the inventory maps. The Pearson's correlation coefficients (r) between xCH(4) and the rice emission inventory data are observed to be greater than similar to 0.6 over typical rice fields, with outstanding r-values of similar to 0.8 in the Ganges Basin, Myanmar, and Thailand. This suggests that the emission of CH4 from rice cultivation mainly controls the seasonality of the CH4 concentration over such regions. The correlation between xCH(4) and LSWC and NDVI is also as large as 0.6. In Southeast Asia, the r-values of xCH4 with bottom-up inventory data that includes all categories are not as high as those with the emission, as estimated from the rice category only. This is indicative of the relative importance of rice emissions among all other emission categories in Southeast Asia. (C) 2013 Elsevier Inc. All rights reserved. |
BibTeX:
@article{hayashida13a,
author = {Hayashida, S. and Ono, A. and Yoshizaki, S. and Frankenberg, C. and Takeuchi, W. and Yan, X.},
title = {Methane concentrations over Monsoon Asia as observed by SCIAMACHY: Signals of methane emission from rice cultivation},
journal = {REMOTE SENSING OF ENVIRONMENT},
year = {2013},
volume = {139},
pages = {246--256},
doi = {10.1016/j.rse.2013.08.008}
}
|
| Hayes DJ, Turner DP, Stinson G, McGuire AD, Wei Y, West TO, Heath LS, Dejong B, McConkey BG, Birdsey RA, Kurz WA, Jacobson AR, Huntzinger DN, Pan Y, Mac Post W and Cook RB ({2012}), "Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data", GLOBAL CHANGE BIOLOGY., APR, {2012}. Vol. {18}({4}), pp. 1282-1299. |
| Abstract: We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000-2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a -327 similar to +/-similar to 252 similar to TgC similar to yr-1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (-248 similar to TgC similar to yr-1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (-297 similar to TgC similar to yr-1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 similar to TgC similar to yr-1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated to be a small net source (+18 similar to TgC similar to yr-1) due to land use change between 1993 and 2002. We compare these inventory-based estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is -511 similar to TgC similar to yr-1 and -931 similar to TgC similar to yr-1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional -239 similar to TgC similar to yr-1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches. |
BibTeX:
@article{hayes12a,
author = {Hayes, Daniel J. and Turner, David P. and Stinson, Graham and McGuire, A. David and Wei, Yaxing and West, Tristram O. and Heath, Linda S. and Dejong, Bernardus and McConkey, Brian G. and Birdsey, Richard A. and Kurz, Werner A. and Jacobson, Andrew R. and Huntzinger, Deborah N. and Pan, Yude and Mac Post, W. and Cook, Robert B.},
title = {Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data},
journal = {GLOBAL CHANGE BIOLOGY},
year = {2012},
volume = {18},
number = {4},
pages = {1282--1299},
doi = {10.1111/j.1365-2486.2011.02627.x}
}
|
| Hayes D and Turner D (2012), "The need for ``apples‐to‐apples'' comparisons of carbon dioxide source and sink estimates", Eos, Transactions American Geophysical Union. Vol. 93(41), pp. 404-405. |
BibTeX:
@article{hayes12b,
author = {Hayes, Daniel and Turner, David},
title = {The need for ``apples‐to‐apples'' comparisons of carbon dioxide source and sink estimates},
journal = {Eos, Transactions American Geophysical Union},
year = {2012},
volume = {93},
number = {41},
pages = {404--405},
doi = {10.1029/2012EO410007/full}
}
|
| Hazan L, Tarniewicz J, Ramonet M, Laurent O and Abbaris A ({2016}), "Automatic processing of atmospheric CO2 and CH4 mole fractions at the ICOS Atmosphere Thematic Centre", ATMOSPHERIC MEASUREMENT TECHNIQUES., SEP 22, {2016}. Vol. {9}({9}), pp. 4719-4736. |
| Abstract: The Integrated Carbon Observation System Atmosphere Thematic Centre (ICOS ATC) automatically processes atmospheric greenhouse gases mole fractions of data coming from sites of the ICOS network. Daily transferred raw data files are automatically processed and archived. Data are stored in the ICOS atmospheric database, the backbone of the system, which has been developed with an emphasis on the traceability of the data processing. Many data products, updated daily, explore the data through different angles to support the quality control of the dataset performed by the principal operators in charge of the instruments. The automatic processing includes calibration and water vapor corrections as described in the paper. The mole fractions calculated in near-real time (NRT) are automatically revaluated as soon as a new instrument calibration is processed or when the station supervisors perform quality control. By analyzing data from 11 sites, we determined that the average calibration corrections are equal to 1.7 +/- 0.3 mu mol mol(-1) for CO2 and 2.8 +/- 3 nmol mol(-1) for CH4. These biases are important to correct to avoid artificial gradients between stations that could lead to error in flux estimates when using atmospheric inversion techniques. We also calculated that the average drift between two successive calibrations separated by 15 days amounts to +/- 0.05 mu mol mol(-1) and +/- 0.7 nmol mol(-1) for CO2 and CH4, respectively. Outliers are generally due to errors in the instrument configuration and can be readily detected thanks to the data products provided by the ATC. Several developments are still ongoing to improve the processing, including automated spike detection and calculation of time-varying uncertainties. |
BibTeX:
@article{hazan16a,
author = {Hazan, Lynn and Tarniewicz, Jerome and Ramonet, Michel and Laurent, Olivier and Abbaris, Amara},
title = {Automatic processing of atmospheric CO2 and CH4 mole fractions at the ICOS Atmosphere Thematic Centre},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2016},
volume = {9},
number = {9},
pages = {4719--4736},
doi = {10.5194/amt-9-4719-2016}
}
|
| He Z, Zeng Z-C, Lei L, Bie N and Yang S ({2017}), "A Data-Driven Assessment of Biosphere-Atmosphere Interaction Impact on Seasonal Cycle Patterns of XCO2 Using GOSAT and MODIS Observations", REMOTE SENSING., MAR, {2017}. Vol. {9}({3}) |
| Abstract: Using measurements of the column-averaged CO2 dry air mole fraction (XCO2) from GOSAT and biosphere parameters, including normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), leaf area index (LAI), gross primary production (GPP), and land surface temperature (LST) from MODIS, this study proposes a data-driven approach to assess the impacts of terrestrial biosphere activities on the seasonal cycle pattern of XCO2. A unique global land mapping dataset of XCO2 with a resolution of 1 degrees by 1 degrees in space, and three days in time, from June 2009 to May 2014, which facilitates the assessment at a fine scale, is first produced from GOSAT XCO2 retrievals. We then conduct a statistical fitting method to obtain the global map of seasonal cycle amplitudes (SCA) of XCO2 and NDVI, and implement correlation analyses of seasonal variation between XCO2 and the vegetation parameters. As a result, the spatial distribution of XCO2 SCA decreases globally with latitude from north to south, which is in good agreement with that of simulated XCO2 from CarbonTracker. The spatial pattern of XCO2 SCA corresponds well to the vegetation seasonal activity revealed by NDVI, with a strong correlation coefficient of 0.74 in the northern hemisphere (NH). Some hotspots in the subtropical areas, including Northern India (with SCA of 8.68 +/- 0.49 ppm on average) and Central Africa (with SCA of 8.33 +/- 0.25 ppm on average), shown by satellite measurements, but missed by model simulations, demonstrate the advantage of satellites in observing the biosphere-atmosphere interactions at local scales. Results from correlation analyses between XCO2 and NDVI, EVI, LAI, or GPP show a consistent spatial distribution, and NDVI and EVI have stronger negative correlations over all latitudes. This may suggest that NDVI and EVI can be better vegetation parameters in characterizing the seasonal variations of XCO2 and its driving terrestrial biosphere activities. We, furthermore, present the global distribution of phase lags of XCO2 compared to NDVI in seasonal variation, which, to our knowledge, is the first such map derived from a completely data-driven approach using satellite observations. The impact of retrieval error of GOSAT data on the mapping data, especially over high-latitude areas, is further discussed. Results from this study provide reference for better understanding the distribution of the strength of carbon sink by terrestrial ecosystems and utilizing remote sensing data in assessing the impact of biosphere-atmosphere interactions on the seasonal cycle pattern of atmospheric CO2 columns. |
BibTeX:
@article{he17a,
author = {He, Zhonghua and Zeng, Zhao-Cheng and Lei, Liping and Bie, Nian and Yang, Shaoyuan},
title = {A Data-Driven Assessment of Biosphere-Atmosphere Interaction Impact on Seasonal Cycle Patterns of XCO2 Using GOSAT and MODIS Observations},
journal = {REMOTE SENSING},
year = {2017},
volume = {9},
number = {3},
doi = {10.3390/rs9030251}
}
|
| He Z, Lei L, Welp LR, Zeng Z-C, Bie N, Yang S and Liu L (2018), "Detection of Spatiotemporal Extreme Changes in Atmospheric CO2 Concentration Based on Satellite Observations", Remote Sensing. Vol. 10 |
BibTeX:
@article{he18a,
author = {Zhonghua He and Liping Lei and Lisa R. Welp and Zhao-Cheng Zeng and Nian Bie and Shaoyuan Yang and Liangyun Liu},
title = {Detection of Spatiotemporal Extreme Changes in Atmospheric CO2 Concentration Based on Satellite Observations},
journal = {Remote Sensing},
year = {2018},
volume = {10},
url = {https://www.mdpi.com/2072-4292/10/6/839}
}
|
| He W, Ju W, Schwaim CR, Sippel S, Wu X, He Q, Song L, Zhang C, Li J, Sitch S, Viovy N, Friedlingstein P and Jain AK ({2018}), "Large-Scale Droughts Responsible for Dramatic Reductions of Terrestrial Net Carbon uptake Over North America in 2011 and 2012", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., JUL, {2018}. Vol. {123}({7}), pp. {2053-2071}. |
| Abstract: Recently, severe droughts that occurred in North America are likely to have impacted its terrestrial carbon sink. However, process-based understanding of how meteorological conditions prior to the onset of drought, for instance warm or cold springs, affect drought-induced carbon cycle effects remains scarce. Here we assess and compare the response of terrestrial carbon fluxes to summer droughts in 2011 and 2012 characterized by contrasting spring conditions. The analysis is based on a comprehensive ensemble of carbon cycle models, including FLUXCOM, TRENDY v5, SiBCASA, CarbonTracker Europe, and CarbonTracker, and emerging Earth observations. In 2011, large reductions of net ecosystem production (NEP; -0.24 +/- 0.17 Pg C/year) are due to decreased gross primary production (-0.17 +/- 0.18 Pg C/year) and slightly increased ecosystem respiration (+0.07 +/- 0.17 Pg C/year). Conversely, in 2012, NEP reductions (-0.17 +/- 0.25 Pg C/year) are attributed to a larger increase of ecosystem respiration (+0.48 +/- 0.27 Pg C/year) than gross primary production (+0.31 +/- 0.29 Pg C/year), induced predominantly by an extra warmer spring prior to summer drought. Two temperate ecoregions crops/agriculture and the grass/shrubs contribute largest to these reductions and also dominate the interannual variations of NEP during 2007-2014. Moreover, the warming spring compensated largely the negative carbon anomaly due to summer drought, consistent with earlier studies; however, the compensation occurred only in some specific ecoregions. Overall, our analysis offers a refined view on recent carbon cycle variability and extremes in North America. It corroborates earlier results but also highlights differences with respect to ecoregion-specific carbon cycle responses to drought and heat. |
BibTeX:
@article{he18b,
author = {He, Wei and Ju, Weimin and Schwaim, Christopher R. and Sippel, Sebastian and Wu, Xiaocui and He, Qiaoning and Song, Lian and Zhang, Chunhua and Li, Jing and Sitch, Stephen and Viovy, Nicolas and Friedlingstein, Pierre and Jain, Atul K.},
title = {Large-Scale Droughts Responsible for Dramatic Reductions of Terrestrial Net Carbon uptake Over North America in 2011 and 2012},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2018},
volume = {123},
number = {7},
pages = {2053-2071},
doi = {{10.1029/2018JG004520}}
}
|
| He W, van der Velde IR, Andrews AE, Sweeney C, Miller J, Tans P, van der Laan-Luijkx IT, Nehrkorn T, Mountain M, Ju W, Peters W and Chen H (2018), "CTDAS-Lagrange v1. 0: A high-resolution data assimilation system for regional carbon dioxide observations", GEOSCIENTIFIC MODEL DEVELOPMENT., AUG, 2018. Vol. 11, pp. 3515-3536. |
BibTeX:
@article{he18c,
author = {Wei He and Ivar R. van der Velde and Arlyn E. Andrews and Colm Sweeney and John Miller and Pieter Tans and Ingrid T. van der Laan-Luijkx and Thomas Nehrkorn and Marikate Mountain and Weimin Ju and Wouter Peters and Huilin Chen},
title = {CTDAS-Lagrange v1. 0: A high-resolution data assimilation system for regional carbon dioxide observations},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2018},
volume = {11},
pages = {3515-3536},
url = {https://www.geosci-model-dev.net/11/3515/2018/gmd-11-3515-2018.pdf}
}
|
| Helbig M, Chasmer LE, Desai AR, Kljun N, Quinton WL and Sonnentag O ({2017}), "Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest-wetland landscape", GLOBAL CHANGE BIOLOGY., AUG, {2017}. Vol. {23}({8}), pp. 3231-3248. |
| Abstract: In the sporadic permafrost zone of northwestern Canada, boreal forest carbon dioxide (CO2) fluxes will be altered directly by climate change through changing meteorological forcing and indirectly through changes in landscape functioning associated with thaw-induced collapse-scar bog (` wetland') expansion. However, their combined effect on landscape-scale net ecosystem CO2 exchange (NEELAND), resulting from changing gross primary productivity (GPP) and ecosystem respiration (ER), remains unknown. Here, we quantify indirect land cover change impacts on NEELAND and direct climate change impacts on modeled temperature-and light-limited NEELAND of a boreal forestwetland landscape. Using nested eddy covariance flux towers, we find both GPP and ER to be larger at the landscape compared to the wetland level. However, annual NEELAND (-20 g C m(-2)) and wetland NEE (-24 g C m(-2)) were similar, suggesting negligible wetland expansion effects on NEELAND. In contrast, we find non-negligible direct climate change impacts when modeling NEELAND using projected air temperature and incoming shortwave radiation. At the end of the 21st century, modeled GPP mainly increases in spring and fall due to reduced temperature limitation, but becomes more frequently light-limited in fall. In a warmer climate, ER increases year-round in the absence of moisture stress resulting in net CO2 uptake increases in the shoulder seasons and decreases during the summer. Annually, landscape net CO2 uptake is projected to decline by 25 +/- 14 g C m(-2) for a moderate and 103 +/- 38 g C m(-2) for a high warming scenario, potentially reversing recently observed positive net CO2 uptake trends across the boreal biome. Thus, even without moisture stress, net CO2 uptake of boreal forest-wetland landscapes may decline, and ultimately, these landscapes may turn into net CO2 sources under continued anthropogenic CO2 emissions. We conclude that NEELAND changes are more likely to be driven by direct climate change rather than by indirect land cover change impacts. |
BibTeX:
@article{helbig17a,
author = {Helbig, Manuel and Chasmer, Laura E. and Desai, Ankur R. and Kljun, Natascha and Quinton, William L. and Sonnentag, Oliver},
title = {Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest-wetland landscape},
journal = {GLOBAL CHANGE BIOLOGY},
year = {2017},
volume = {23},
number = {8},
pages = {3231--3248},
doi = {10.1111/gcb.13638}
}
|
| Hernandez-Carrasco I, Sudre J, Garcon V, Yahia H, Garbe C, Paulmier A, Dewitte B, Illig S, Dadou I, Gonzalez-Davila M and Santana-Casiano JM ({2015}), "Reconstruction of super-resolution ocean pCO(2) and air-sea fluxes of CO2 from satellite imagery in the southeastern Atlantic", BIOGEOSCIENCES. Vol. {12}({17}), pp. 5229-5245. |
| Abstract: An accurate quantification of the role of the ocean as source/sink of greenhouse gases (GHGs) requires to access the high-resolution of the GHG air-sea flux at the interface. In this paper we present a novel method to reconstruct maps of surface ocean partial pressure of CO2 (pCO(2)) and air-sea CO2 fluxes at super resolution (4 km, i.e., 1/32 degrees at these latitudes) using sea surface temperature (SST) and ocean color (OC) data at this resolution, and CarbonTracker CO2 fluxes data at low resolution (110 km). Inference of super-resolution pCO(2) and air-sea CO2 fluxes is performed using novel nonlinear signal processing methodologies that prove efficient in the context of oceanography. The theoretical background comes from the microcanonical multi-fractal formalism which unlocks the geometrical determination of cascading properties of physical intensive variables. As a consequence, a multi-resolution analysis performed on the signal of the so-called singularity exponents allows for the correct and near optimal cross-scale inference of GHG fluxes, as the inference suits the geometric realization of the cascade. We apply such a methodology to the study offshore of the Benguela area. The inferred representation of oceanic partial pressure of CO2 improves and enhances the description provided by CarbonTracker, capturing the small-scale variability. We examine different combinations of ocean color and sea surface temperature products in order to increase the number of valid points and the quality of the inferred pCO(2) field. The methodology is validated using in situ measurements by means of statistical errors. We find that mean absolute and relative errors in the inferred values of pCO(2) with respect to in situ measurements are smaller than for CarbonTracker. |
BibTeX:
@article{hernandez-carrasco15a,
author = {Hernandez-Carrasco, I. and Sudre, J. and Garcon, V. and Yahia, H. and Garbe, C. and Paulmier, A. and Dewitte, B. and Illig, S. and Dadou, I. and Gonzalez-Davila, M. and Santana-Casiano, J. M.},
title = {Reconstruction of super-resolution ocean pCO(2) and air-sea fluxes of CO2 from satellite imagery in the southeastern Atlantic},
journal = {BIOGEOSCIENCES},
year = {2015},
volume = {12},
number = {17},
pages = {5229--5245},
doi = {10.5194/bg-12-5229-2015}
}
|
| Hernandez-Carrasco I, Garcon V, Sudre J, Garbe C and Yahia H ({2018}), "Increasing the Resolution of Ocean pCO(2) Maps in the South Eastern Atlantic Ocean Merging Multifractal Satellite-Derived Ocean Variables", IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING., NOV, {2018}. Vol. {56}({11}), pp. {6596-6610}. |
| Abstract: A new methodology has been developed in order to improve the description of the spatial and temporal variability of not well-resolved oceanic variables from other well-observed high-resolution oceanic variables. The method is based on the cross-scale inference of information, incorporating the common features of different multifractal high-resolution variables into a coarser one. An exercise of validation of the methodology has been performed based on the outputs of coupled physical-biogeochemical Regional Ocean Modeling System adapted to the eastern boundary upwelling systems at two spatial resolutions. Once the algorithm has been proved to he effective in increasing the spatial resolution of modeled partial pressure of CO2 at the surface ocean (pCO(2)), we have investigated the capability of our methodology when it is applied to remote sensing data, focusing on the improvement of the temporal description. In this regard, we have inferred daily pCO(2) maps at high resolution (4 km, i.e., 1/24 degrees) fusing monthly pCO(2) data at low resolution (100 kin, i.e., 1 degrees) with the small-scale features contained in daily high-resolution maps of satellite sea surface temperature and Chlorophyll-a. The algorithm has been applied to the South Eastern Atlantic Ocean opening the possibility to obtain an accurate quantification of the CO2 fluxes in relevant coastal regions, such as the eastern boundary upwelling systems. Outputs of our algorithm have been compared with in situ measurements, showing that daily maps inferred from monthly products are in average 6 mu atm closer to the in situ values than the original coarser monthly maps. Furthermore, values of pCO(2) have been improved in points close to the coast with respect to the original input data. |
BibTeX:
@article{hernandez-carrasco18a,
author = {Hernandez-Carrasco, Ismael and Garcon, Veronique and Sudre, Joel and Garbe, Christoph and Yahia, Hussein},
title = {Increasing the Resolution of Ocean pCO(2) Maps in the South Eastern Atlantic Ocean Merging Multifractal Satellite-Derived Ocean Variables},
journal = {IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING},
year = {2018},
volume = {56},
number = {11},
pages = {6596-6610},
doi = {{10.1109/TGRS.2018.2840526}}
}
|
| Heymann J, Schneising O, Reuter M, Buchwitz M, Rozanov VV, Velazco VA, Bovensmann H and Burrows JP ({2012}), "SCIAMACHY WFM-DOAS XCO2: comparison with CarbonTracker XCO2 focusing on aerosols and thin clouds", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({8}), pp. 1935-1952. |
| Abstract: Carbon dioxide (CO2) is the most important greenhouse gas whose atmospheric loading has been significantly increased by anthropogenic activity leading to global warming. Accurate measurements and models are needed in order to reliably predict our future climate. This, however, has challenging requirements. Errors in measurements and models need to be identified and minimised. In this context, we present a comparison between satellite-derived column-averaged dry air mole fractions of CO2, denoted XCO2, retrieved from SCIAMACHY/ENVISAT using the WFM-DOAS (weighting function modified differential optical absorption spectroscopy) algorithm, and output from NOAA's global CO2 modelling and assimilation system CarbonTracker. We investigate to what extent differences between these two data sets are influenced by systematic retrieval errors due to aerosols and unaccounted clouds. We analyse seven years of SCIAMACHY WFM-DOAS version 2.1 retrievals (WFMDv2.1) using CarbonTracker version 2010. We investigate to what extent the difference between SCIAMACHY and CarbonTracker XCO2 are temporally and spatially correlated with global aerosol and cloud data sets. For this purpose, we use a global aerosol data set generated within the European GEMS project, which is based on assimilated MODIS satellite data. For clouds, we use a data set derived from CALIOP/CALIPSO. We find significant correlations of the SCIAMACHY minus CarbonTracker XCO2 difference with thin clouds over the Southern Hemisphere. The maximum temporal correlation we find for Darwin, Australia (r(2) = 54. Large temporal correlations with thin clouds are also observed over other regions of the Southern Hemisphere (e. g. 43% for South America and 31% for South Africa). Over the Northern Hemisphere the temporal correlations are typically much lower. An exception is India, where large temporal correlations with clouds and aerosols have also been found. For all other regions the temporal correlations with aerosol are typically low. For the spatial correlations the picture is less clear. They are typically low for both aerosols and clouds, but depending on region and season, they may exceed 30% (the maximum value of 46% has been found for Darwin during September to November). Overall we find that the presence of thin clouds can potentially explain a significant fraction of the difference between SCIAMACHY WFMDv2.1 XCO2 and CarbonTracker over the Southern Hemisphere. Aerosols appear to be less of a problem. Our study indicates that the quality of the satellite derived XCO2 will significantly benefit from a reduction of scattering related retrieval errors at least for the Southern Hemisphere. |
BibTeX:
@article{heymann12a,
author = {Heymann, J. and Schneising, O. and Reuter, M. and Buchwitz, M. and Rozanov, V. V. and Velazco, V. A. and Bovensmann, H. and Burrows, J. P.},
title = {SCIAMACHY WFM-DOAS XCO2: comparison with CarbonTracker XCO2 focusing on aerosols and thin clouds},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2012},
volume = {5},
number = {8},
pages = {1935--1952},
doi = {10.5194/amt-5-1935-2012}
}
|
| Heymann J, Bovensmann H, Buchwitz M, Burrows JP, Deutscher NM, Notholt J, Rettinger M, Reuter M, Schneising O, Sussmann R and Warneke T ({2012}), "SCIAMACHY WFM-DOAS XCO2: reduction of scattering related errors", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({10}), pp. 2375-2390. |
| Abstract: Global observations of column-averaged dry air mole fractions of carbon dioxide (CO2), denoted by XCO2, retrieved from SCIAMACHY on-board ENVISAT can provide important and missing global information on the distribution and magnitude of regional CO2 surface fluxes. This application has challenging precision and accuracy requirements. In a previous publication (Heymann et al., 2012), it has been shown by analysing seven years of SCIAMACHY WFM-DOAS XCO2 (WFMDv2.1) that unaccounted thin cirrus clouds can result in significant errors. In order to enhance the quality of the SCIAMACHY XCO2 data product, we have developed a new version of the retrieval algorithm (WFMDv2.2), which is described in this manuscript. It is based on an improved cloud filtering and correction method using the 1.4 mu m strong water vapour absorption and 0.76 mu m O-2-A bands. The new algorithm has been used to generate a SCIAMACHY XCO2 data set covering the years 2003-2009. The new XCO2 data set has been validated using ground-based observations from the Total Carbon Column Observing Network (TCCON). The validation shows a significant improvement of the new product (v2.2) in comparison to the previous product (v2.1). For example, the standard deviation of the difference to TCCON at Darwin, Australia, has been reduced from 4 ppm to 2 ppm. The monthly regional-scale scatter of the data (defined as the mean intra-monthly standard deviation of all quality filtered XCO2 retrievals within a radius of 350 km around various locations) has also been reduced, typically by a factor of about 1.5. Overall, the validation of the new WFMDv2.2 XCO2 data product can be summarised by a single measurement precision of 3.8 ppm, an estimated regional-scale (radius of 500 km) precision of monthly averages of 1.6 ppm and an estimated regional-scale relative accuracy of 0.8 ppm. In addition to the comparison with the limited number of TCCON sites, we also present a comparison with NOAA's global CO2 modelling and assimilation system Carbon-Tracker. This comparison also shows significant improvements especially over the Southern Hemisphere. |
BibTeX:
@article{heymann12b,
author = {Heymann, J. and Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Deutscher, N. M. and Notholt, J. and Rettinger, M. and Reuter, M. and Schneising, O. and Sussmann, R. and Warneke, T.},
title = {SCIAMACHY WFM-DOAS XCO2: reduction of scattering related errors},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2012},
volume = {5},
number = {10},
pages = {2375--2390},
doi = {10.5194/amt-5-2375-2012}
}
|
| Heymann J (2013), "Satellite measurements of carbon dioxide: impact and consideration of atmospheric scattering on the data retrieval and interpretation". Thesis at: Universität Bremen. |
BibTeX:
@phdthesis{heymann13a,
author = {Heymann, Jens},
title = {Satellite measurements of carbon dioxide: impact and consideration of atmospheric scattering on the data retrieval and interpretation},
school = {Universität Bremen},
year = {2013},
url = {https://d-nb.info/1072047985/34}
}
|
| Heymann J, Reuter M, Hilker M, Buchwitz M, Schneising O, Bovensmann H, Burrows JP, Kuze A, Suto H, Deutscher NM, Dubey MK, Griffith DWT, Hase F, Kawakami S, Kivi R, Morino I, Petri C, Roehl C, Schneider M, Sherlock V, Sussmann R, Velazco VA, Warneke T and Wunch D ({2015}), "Consistent satellite XCO2 retrievals from SCIAMACHY and GOSAT using the BESD algorithm", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({7}), pp. 2961-2980. |
| Abstract: Consistent and accurate long-term data sets of global atmospheric concentrations of carbon dioxide (CO2) are required for carbon cycle and climate-related research. However, global data sets based on satellite observations may suffer from inconsistencies originating from the use of products derived from different satellites as needed to cover a long enough time period. One reason for inconsistencies can be the use of different retrieval algorithms. We address this potential issue by applying the same algorithm, the Bremen Optimal Estimation DOAS (BESD) algorithm, to different satellite instruments, SCIAMACHY on-board ENVISAT (March 2002-April 2012) and TANSO-FTS onboard GOSAT (launched in January 2009), to retrieve XCO2, the column-averaged dry-air mole fraction of CO2. BESD has been initially developed for SCIAMACHY XCO2 retrievals. Here, we present the first detailed assessment of the new GOSAT BESD XCO2 product. GOSAT BESD XCO2 is a product generated and delivered to the MACC project for assimilation into ECMWF's Integrated Forecasting System. We describe the modifications of the BESD algorithm needed in order to retrieve XCO2 from GOSAT and present de-tailed comparisons with ground-based observations of XCO2 from the Total Carbon Column Observing Network (TCCON). We discuss detailed comparison results between all three XCO2 data sets (SCIAMACHY, GOSAT and TCCON). The comparison results demonstrate the good consistency between SCIAMACHY and GOSAT XCO2. For example, we found a mean difference for daily averages of -0.60 +/- 1.56 ppm (mean difference +/- standard deviation) for GOSAT-SCIAMACHY (linear correlation coefficient r = 0.82), -0.34 +/- 1.37 ppm (r = 0.86) for GOSAT-TCCON and 0.10 +/- 1.79 ppm (r = 0.75) for SCIAMACHY-TCCON. The remaining differences between GOSAT and SCIAMACHY are likely due to non-perfect collocation (+/- 2 h, 10 degrees x 10 degrees around TCCON sites), i.e. the observed air masses are not exactly identical but likely also due to a still non-perfect BESD retrieval algorithm, which will be continuously improved in the future. Our overarching goal is to generate a satellite-derived XCO2 data set appropriate for climate and carbon cycle research covering the longest possible time period. We therefore also plan to extend the existing SCIAMACHY and GOSAT data set discussed here by also using data from other missions (e.g. OCO-2, GOSAT-2, CarbonSat) in the future. |
BibTeX:
@article{heymann15a,
author = {Heymann, J. and Reuter, M. and Hilker, M. and Buchwitz, M. and Schneising, O. and Bovensmann, H. and Burrows, J. P. and Kuze, A. and Suto, H. and Deutscher, N. M. and Dubey, M. K. and Griffith, D. W. T. and Hase, F. and Kawakami, S. and Kivi, R. and Morino, I. and Petri, C. and Roehl, C. and Schneider, M. and Sherlock, V. and Sussmann, R. and Velazco, V. A. and Warneke, T. and Wunch, D.},
title = {Consistent satellite XCO2 retrievals from SCIAMACHY and GOSAT using the BESD algorithm},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2015},
volume = {8},
number = {7},
pages = {2961--2980},
doi = {10.5194/amt-8-2961-2015}
}
|
| Heymann J, Reuter M, Buchwitz M, Schneising O, Bovensmann H, Burrows JP, Massart S, Kaiser JW and Crisp D ({2017}), "CO2 emission of Indonesian fires in 2015 estimated from satellite-derived atmospheric CO2 concentrations", GEOPHYSICAL RESEARCH LETTERS., FEB 16, {2017}. Vol. {44}({3}), pp. 1537-1544. |
| Abstract: Indonesia experienced an exceptional number of fires in 2015 as a result of droughts related to the recent El Nio event and human activities. These fires released large amounts of carbon dioxide (CO2) into the atmosphere. Emission databases such as the Global Fire Assimilation System version 1.2 and the Global Fire Emission Database version 4s estimated the CO2 emission to be approximately 1100 MtCO(2) in the time period from July to November 2015. This emission was indirectly estimated by using parameters like burned area, fire radiative power, and emission factors. In the study presented in this paper, we estimate the Indonesian fire CO2 emission by using the column-averaged dry air mole fraction of CO2, XCO2, derived from measurements of the Orbiting Carbon Observatory-2 satellite mission. The estimated CO2 emission is 748 +/- 209 MtCO(2), which is about 30% lower than provided by the emission databases. |
BibTeX:
@article{heymann17a,
author = {Heymann, J. and Reuter, M. and Buchwitz, M. and Schneising, O. and Bovensmann, H. and Burrows, J. P. and Massart, S. and Kaiser, J. W. and Crisp, D.},
title = {CO2 emission of Indonesian fires in 2015 estimated from satellite-derived atmospheric CO2 concentrations},
journal = {GEOPHYSICAL RESEARCH LETTERS},
year = {2017},
volume = {44},
number = {3},
pages = {1537--1544},
doi = {10.1002/2016GL072042}
}
|
| Hilton TW (2011), "Spatial structure in North American terrestrial biological carbon fluxes and flux model errors evaluated with a simple land surface model". Thesis at: The Pennsylvania State University. |
BibTeX:
@phdthesis{hilton11a,
author = {Hilton, Timothy William},
title = {Spatial structure in North American terrestrial biological carbon fluxes and flux model errors evaluated with a simple land surface model},
school = {The Pennsylvania State University},
year = {2011},
url = {http://search.proquest.com/openview/ad1f013a7f8d52fe468d7ba861602aa1/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Hilton TW, Davis KJ, Keller K and Urban NM ({2013}), "Improving North American terrestrial CO2 flux diagnosis using spatial structure in land surface model residuals", BIOGEOSCIENCES. Vol. {10}({7}), pp. 4607-4625. |
| Abstract: We evaluate spatial structure in North American CO2 flux observations using a simple diagnostic land surface model. The vegetation photosynthesis respiration model (VPRM) calculates net ecosystem exchange (NEE) using locally observed temperature and photosynthetically active radiation (PAR) along with satellite-derived phenology and moisture. We use observed NEE from a group of 65 North American eddy covariance tower sites spanning North America to estimate VPRM parameters for these sites. We investigate spatial coherence in regional CO2 fluxes at several different time scales by using geostatistical methods to examine the spatial structure of model-data residuals. We find that persistent spatial structure does exist in the model-data residuals at a length scale of approximately 400 km (median 402 km, mean 712 km, standard deviation 931 km). This spatial structure defines a flux-tower-based VPRM residual covariance matrix. The residual covariance matrix is useful in constructing prior fluxes for atmospheric CO2 concentration inversion calculations, as well as for constructing a VPRM North American CO2 flux map optimized to eddy covariance observations. Finally (and secondarily), the estimated VPRM parameter values do not separate clearly by plant functional type (PFT). This calls into question whether PFTs can successfully partition ecosystems' fundamental ecological drivers when the viewing lens is a simple model. |
BibTeX:
@article{hilton13a,
author = {Hilton, T. W. and Davis, K. J. and Keller, K. and Urban, N. M.},
title = {Improving North American terrestrial CO2 flux diagnosis using spatial structure in land surface model residuals},
journal = {BIOGEOSCIENCES},
year = {2013},
volume = {10},
number = {7},
pages = {4607--4625},
doi = {10.5194/bg-10-4607-2013}
}
|
| Hilton TW, Davis KJ and Keller K ({2014}), "Evaluating terrestrial CO2 flux diagnoses and uncertainties from a simple land surface model and its residuals", BIOGEOSCIENCES. Vol. {11}({2}), pp. 217-235. |
| Abstract: Global terrestrial atmosphere-ecosystem carbon dioxide fluxes are well constrained by the concentration and isotopic composition of atmospheric carbon dioxide. In contrast, considerable uncertainty persists surrounding regional contributions to the net global flux as well as the impacts of atmospheric and biological processes that drive the net flux. These uncertainties severely limit our ability to make confident predictions of future terrestrial biological carbon fluxes. Here we use a simple light-use efficiency land surface model (the Vegetation Photosynthesis Respiration Model, VPRM) driven by remotely sensed temperature, moisture, and phenology to diagnose North American gross ecosystem exchange (GEE), ecosystem respiration, and net ecosystem exchange (NEE) for the period 2001 to 2006. We optimize VPRM parameters to eddy covariance (EC) NEE observations from 65 North American FluxNet sites. We use a separate set of 27 cross-validation FluxNet sites to evaluate a range of spatial and temporal resolutions for parameter estimation. With these results we demonstrate that different spatial and temporal groupings of EC sites for parameter estimation achieve similar sum of squared residuals values through radically different spatial patterns of NEE. We also derive a regression model to estimate observed VPRM errors as a function of VPRM NEE, temperature, and precipitation. Because this estimate is based on model-observation residuals it is comprehensive of all the error sources present in modeled fluxes. We find that 1 km interannual variability in VPRM NEE is of similar magnitude to estimated 1 km VPRM NEE errors. |
BibTeX:
@article{hilton14a,
author = {Hilton, T. W. and Davis, K. J. and Keller, K.},
title = {Evaluating terrestrial CO2 flux diagnoses and uncertainties from a simple land surface model and its residuals},
journal = {BIOGEOSCIENCES},
year = {2014},
volume = {11},
number = {2},
pages = {217--235},
doi = {10.5194/bg-11-217-2014}
}
|
| Houweling S, Aben I, Breon F-M, Chevallier F, Deutscher N, Engelen R, Gerbig C, Griffith D, Hungershoefer K, Macatangay R, Marshall J, Notholt J, Peters W and Serrar S ({2010}), "The importance of transport model uncertainties for the estimation of CO2 sources and sinks using satellite measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({20}), pp. 9981-9992. |
| Abstract: This study presents a synthetic model intercomparison to investigate the importance of transport model errors for estimating the sources and sinks of CO2 using satellite measurements. The experiments were designed for testing the potential performance of the proposed CO2 lidar A-SCOPE, but also apply to other space borne missions that monitor total column CO2. The participating transport models IFS, LMDZ, TM3, and TM5 were run in forward and inverse mode using common a priori CO2 fluxes and initial concentrations. Forward simulations of column averaged CO2 (xCO(2)) mixing ratios vary between the models by sigma = 0.5 ppm over the continents and sigma = 0.27 ppm over the oceans. Despite the fact that the models agree on average on the sub-ppm level, these modest differences nevertheless lead to significant discrepancies in the inverted fluxes of 0.1 PgC/yr per 10(6) km(2) over land and 0.03 PgC/yr per 10(6) km(2) over the ocean. These transport model induced flux uncertainties exceed the target requirement that was formulated for the A-SCOPE mission of 0.02 PgC/yr per 10(6) km(2), and could also limit the overall performance of other CO2 missions such as GOSAT. A variable, but overall encouraging agreement is found in comparison with FTS measurements at Park Falls, Darwin, Spitsbergen, and Bremen, although systematic differences are found exceeding the 0.5 ppm level. Because of this, our estimate of the impact of transport model uncerainty is likely to be conservative. It is concluded that to make use of the remote sensing technique for quantifying the sources and sinks of CO2 not only requires highly accurate satellite instruments, but also puts stringent requirements on the performance of atmospheric transport models. Improving the accuracy of these models should receive high priority, which calls for a closer collaboration between experts in atmospheric dynamics and tracer transport. |
BibTeX:
@article{houweling10a,
author = {Houweling, S. and Aben, I. and Breon, F-M and Chevallier, F. and Deutscher, N. and Engelen, R. and Gerbig, C. and Griffith, D. and Hungershoefer, K. and Macatangay, R. and Marshall, J. and Notholt, J. and Peters, W. and Serrar, S.},
title = {The importance of transport model uncertainties for the estimation of CO2 sources and sinks using satellite measurements},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2010},
volume = {10},
number = {20},
pages = {9981--9992},
doi = {10.5194/acp-10-9981-2010}
}
|
| Houweling S, Krol M, Bergamaschi P, Frankenberg C, Dlugokencky EJ, Morino I, Notholt J, Sherlock V, Wunch D, Beck V, Gerbig C, Chen H, Kort EA, Rockmann T and Aben I ({2014}), "A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({8}), pp. 3991-4012. |
| Abstract: This study investigates the use of total column CH4 (XCH4) retrievals from the SCIAMACHY satellite instrument for quantifying large-scale emissions of methane. A unique data set from SCIAMACHY is available spanning almost a decade of measurements, covering a period when the global CH4 growth rate showed a marked transition from stable to increasing mixing ratios. The TM5 4DVAR inverse modelling system has been used to infer CH4 emissions from a combination of satellite and surface measurements for the period 2003-2010. In contrast to earlier inverse modelling studies, the SCIAMACHY retrievals have been corrected for systematic errors using the TCCON network of ground-based Fourier transform spectrometers. The aim is to further investigate the role of bias correction of satellite data in inversions. Methods for bias correction are discussed, and the sensitivity of the optimized emissions to alternative bias correction functions is quantified. It is found that the use of SCIAMACHY retrievals in TM5 4DVAR increases the estimated inter-annual variability of large-scale fluxes by 22% compared with the use of only surface observations. The difference in global methane emissions between 2-year periods before and after July 2006 is estimated at 27-35 Tg yr(-1). The use of SCIAMACHY retrievals causes a shift in the emissions from the extra-tropics to the tropics of 50 +/- 25 Tg yr(-1). The large uncertainty in this value arises from the uncertainty in the bias correction functions. Using measurements from the HIPPO and BARCA aircraft campaigns, we show that systematic errors in the SCIAMACHY measurements are a main factor limiting the performance of the inversions. To further constrain tropical emissions of methane using current and future satellite missions, extended validation capabilities in the tropics are of critical importance. |
BibTeX:
@article{houweling14a,
author = {Houweling, S. and Krol, M. and Bergamaschi, P. and Frankenberg, C. and Dlugokencky, E. J. and Morino, I. and Notholt, J. and Sherlock, V. and Wunch, D. and Beck, V. and Gerbig, C. and Chen, H. and Kort, E. A. and Rockmann, T. and Aben, I.},
title = {A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2014},
volume = {14},
number = {8},
pages = {3991--4012},
doi = {10.5194/acp-14-3991-2014}
}
|
| Houweling S, Bergamaschi P, Chevallier F, Heimann M, Kaminski T, Krol M, Michalak AM and Patra P ({2017}), "Global inverse modeling of CH4 sources and sinks: an overview of methods", ATMOSPHERIC CHEMISTRY AND PHYSICS., JAN 4, {2017}. Vol. {17}({1}), pp. 235-256. |
| Abstract: The aim of this paper is to present an overview of inverse modeling methods that have been developed over the years for estimating the global sources and sinks of CH4. It provides insight into how techniques and estimates have evolved over time and what the remaining shortcomings are. As such, it serves a didactical purpose of introducing apprentices to the field, but it also takes stock of developments so far and reflects on promising new directions. The main focus is on methodological aspects that are particularly relevant for CH4, such as its atmospheric oxidation, the use of methane isotopologues, and specific challenges in atmospheric transport modeling of CH4. The use of satellite retrievals receives special attention as it is an active field of methodological development, with special requirements on the sampling of the model and the treatment of data uncertainty. Regional scale flux estimation and attribution is still a grand challenge, which calls for new methods capable of combining information from multiple data streams of different measured parameters. A process model representation of sources and sinks in atmospheric transport inversion schemes allows the integrated use of such data. These new developments are needed not only to improve our understanding of the main processes driving the observed global trend but also to support international efforts to reduce greenhouse gas emissions. |
BibTeX:
@article{houweling17a,
author = {Houweling, Sander and Bergamaschi, Peter and Chevallier, Frederic and Heimann, Martin and Kaminski, Thomas and Krol, Maarten and Michalak, Anna M. and Patra, Prabir},
title = {Global inverse modeling of CH4 sources and sinks: an overview of methods},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {1},
pages = {235--256},
doi = {10.5194/acp-17-235-2017}
}
|
| Hsueh D (2009), "New York City's Metropolitan Dome: past and present CO2 concentration patterns from an urban to rural gradient". Thesis at: Columbia University, New York.
[BibTeX] |
BibTeX:
@mastersthesis{hsueh09a,
author = {Hsueh, Diana},
title = {New York City's Metropolitan Dome: past and present CO2 concentration patterns from an urban to rural gradient},
school = {Columbia University, New York},
year = {2009}
}
|
| Hu L, Montzka SA, Miller JB, Andrews AE, Lehman SJ, Miller BR, Thoning K, Sweeney C, Chen H, Godwin DS, Masarie K, Bruhwiler L, Fischer ML, Biraud SC, Torn MS, Mountain M, Nehrkorn T, Eluszkiewicz J, Miller S, Draxler RR, Stein AF, Hall BD, Elkins JW and Tans PP ({2015}), "US emissions of HFC-134a derived for 2008-2012 from an extensive flask-air sampling network", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 27, {2015}. Vol. {120}({2}), pp. 801-825. |
| Abstract: U.S. national and regional emissions of HFC-134a are derived for 2008-2012 based on atmospheric observations from ground and aircraft sites across the U.S. and a newly developed regional inverse model. Synthetic data experiments were first conducted to optimize the model assimilation design and to assess model-data mismatch errors and prior flux error covariances computed using a maximum likelihood estimation technique. The synthetic data experiments also tested the sensitivity of derived national and regional emissions to a range of assumed prior emissions, with the goal of designing a system that was minimally reliant on the prior. We then explored the influence of additional sources of error in inversions with actual observations, such as those associated with background mole fractions and transport uncertainties. Estimated emissions of HFC-134a range from 52 to 61 Gg yr(-1) for the contiguous U.S. during 2008-2012 for inversions using air transport from Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model driven by the 12km resolution meteorogical data from North American Mesoscale Forecast System (NAM12) and all tested combinations of prior emissions and background mole fractions. Estimated emissions for 2008-2010 were 20% lower when specifying alternative transport from Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by the Weather Research and Forecasting (WRF) meteorology. Our estimates (for HYSPLIT-NAM12) are consistent with annual emissions reported by U.S. Environmental Protection Agency for the full study interval. The results suggest a 10-20% drop in U.S. national HFC-134a emission in 2009 coincident with a reduction in transportation-related fossil fuel CO2 emissions, perhaps related to the economic recession. All inversions show seasonal variation in national HFC-134a emissions in all years, with summer emissions greater than winter emissions by 20-50%. |
BibTeX:
@article{hu15a,
author = {Hu, Lei and Montzka, Stephen A. and Miller, John B. and Andrews, Aryln E. and Lehman, Scott J. and Miller, Benjamin R. and Thoning, Kirk and Sweeney, Colm and Chen, Huilin and Godwin, David S. and Masarie, Kenneth and Bruhwiler, Lori and Fischer, Marc L. and Biraud, Sebastien C. and Torn, Margaret S. and Mountain, Marikate and Nehrkorn, Thomas and Eluszkiewicz, Janusz and Miller, Scot and Draxler, Roland R. and Stein, Ariel F. and Hall, Bradley D. and Elkins, James W. and Tans, Pieter P.},
title = {US emissions of HFC-134a derived for 2008-2012 from an extensive flask-air sampling network},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2015},
volume = {120},
number = {2},
pages = {801--825},
doi = {10.1002/2014JD022617}
}
|
| Hu C, Griffis TJ, Lee X, Millet DB, Chen Z, Baker JM and Xiao K ({2018}), "Top-Down Constraints on Anthropogenic CO2 Emissions Within an Agricultural-Urban Landscape", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 16, {2018}. Vol. {123}({9}), pp. {4674-4694}. |
| Abstract: Anthropogenic carbon dioxide (CO2) emissions dominate the atmospheric greenhouse gas radiative forcing budget. However, these emissions are poorly constrained at the regional (10(2)-10(6)km(2)) and seasonal scales. Here we use a combination of tall tower CO2 mixing ratio and carbon isotope ratio observations and inverse modeling techniques to constrain anthropogenic CO2 emissions within a highly heterogeneous agricultural landscape near Saint Paul, Minnesota, in the Upper Midwestern United States. The analyses indicate that anthropogenic emissions contributed 6.6, 6.8, and 7.4mol/mol annual CO2 enhancements (i.e., departures from the background values) in 2008, 2009, and 2010, respectively. Oil refinery, the energy industry (power and heat generation), and residential emissions (home heating and cooking) contributed 2.9 (42.5, 1.4 (19.8, and 1.1mol/mol (15.8 of the total anthropogenic enhancement over the 3-year period according to a priori inventories. The total anthropogenic signal was further partitioned into CO2 emissions derived from fuel oil, natural gas, coal, gasoline, and diesel consumption using inverse modeling and carbon isotope ratio analyses. The results indicate that fuel oil and natural gas consumption accounted for 52.5% of the anthropogenic CO2 sources in winter. Here the a posteriori CO2 emission from natural gas was 79.04.1% (a priori 20.0 and accounted for 63% of the total CO2 enhancement including both biological and anthropogenic sources. The a posteriori CO2 emission from fuel oil was 8.43.8% (a priori 32.5suggesting a more important role of residential heating in winter. The modeled carbon isotope ratio of the CO2 source (delta C-13(s), -29.3 +/- 0.4 was relatively more enriched in C-13-CO2 compared to that derived from Miller-Tans plot analyses (-35.5 parts per thousand to -34.8 parts per thousand), supporting that natural gas consumption was underestimated for this region. |
BibTeX:
@article{hu18a,
author = {Hu, Cheng and Griffis, Timothy J. and Lee, Xuhui and Millet, Dylan B. and Chen, Zichong and Baker, John M. and Xiao, Ke},
title = {Top-Down Constraints on Anthropogenic CO2 Emissions Within an Agricultural-Urban Landscape},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2018},
volume = {123},
number = {9},
pages = {4674-4694},
doi = {{10.1029/2017JD027881}}
}
|
| Hu H, Landgraf J, Detmers R, Borsdorff T, de Brugh JA, Aben I, Butz A and Hasekamp O ({2018}), "Toward Global Mapping of Methane With TROPOMI: First Results and Intersatellite Comparison to GOSAT", GEOPHYSICAL RESEARCH LETTERS., APR 28, {2018}. Vol. {45}({8}), pp. {3682-3689}. |
| Abstract: The TROPOspheric Monitoring Instrument (TROPOMI), launched on 13 October 2017, aboard the Sentinel-5 Precursor satellite, measures reflected sunlight in the ultraviolet, visible, near-infrared, and shortwave infrared spectral range. It enables daily global mapping of key atmospheric species for monitoring air quality and climate. We present the first methane observations from November and December 2017, using TROPOMI radiance measurements in the shortwave infrared band around 2.3 mu m. We compare our results with the methane product obtained from the Greenhouse gases Observing SAT-ellite (GOSAT). Although different spectral ranges and retrieval methods are used, we find excellent agreement between the methane products acquired from the two satellites with a mean difference of 13.6 ppb, standard deviation of 19.6 ppb, and Pearson's correlation coefficient of 0.95. Our preliminary results capture the latitudinal gradient and show expected regional enhancements, for example, in the African Sudd wetlands, with much more detail than has been observed before. Plain Language Summary Methane is the second most important anthropogenic greenhouse gas. Improved knowledge about methane variations and detection of localized sources is of great importance for scientists, policy makers, and private companies. One of the goals of the recently launched European Space Agency Sentinel-5 Precursor satellite, with on board the cutting-edge TROPOspheric Monitoring Instrument (TROPOMI), is to measure methane with an unprecedented combination of accuracy, spatial coverage, and resolution. This work presents the first TROPOMI methane measurements and shows that these are in excellent agreement with methane measurements from the validated Japanese Greenhouse gases Observing SATellite satellite. |
BibTeX:
@article{hu18b,
author = {Hu, Haili and Landgraf, Jochen and Detmers, Rob and Borsdorff, Tobias and de Brugh, Joost Aan and Aben, Ilse and Butz, Andre and Hasekamp, Otto},
title = {Toward Global Mapping of Methane With TROPOMI: First Results and Intersatellite Comparison to GOSAT},
journal = {GEOPHYSICAL RESEARCH LETTERS},
year = {2018},
volume = {45},
number = {8},
pages = {3682-3689},
doi = {{10.1002/2018GL077259}}
}
|
| Hu C, Liu S, Wang Y, Zhang M, Xiao W, Wang W and Xu J ({2018}), "Anthropogenic CO2 emissions from a megacity in the Yangtze River Delta of China", ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH., AUG, {2018}. Vol. {25}({23, SI}), pp. {23157-23169}. |
| Abstract: Anthropogenic CO2 emissions from cities represent a major source contributing to the global atmospheric CO2 burden. Here, we examined the enhancement of atmospheric CO2 mixing ratios by anthropogenic emissions within the Yangtze River Delta (YRD), China, one of the world's most densely populated regions (population greater than 150 million). Tower measurements of CO2 mixing ratios were conducted from March 2013 to August 2015 and were combined with numerical source footprint modeling to help constrain the anthropogenic CO2 emissions. We simulated the CO2 enhancements (i.e., fluctuations superimposed on background values) for winter season (December, January, and February). Overall, we observed mean diurnal variation of CO2 enhancement of 23.5 similar to 49.7 mu mol mol(-1), 21.4 similar to 52.4 mu mol mol(-1), 28.1 similar to 55.4 mu mol mol(-1), and 29.5 similar to 42.4 mu mol mol(-1) in spring, summer, autumn, and winter, respectively. These enhancements were much larger than previously reported values for other countries. The diurnal CO2 enhancements reported here showed strong similarity for all 3 years of the study. Results from source footprint modeling indicated that our tower observations adequately represent emissions from the broader YRD area. Here, the east of Anhui and the west of Jiangsu province contributed significantly more to the anthropogenic CO2 enhancement compared to the other sectors of YRD. The average anthropogenic CO2 emission in 2014 was 0.162 (+/- 0.005) mg m(-2) s(-1) and was 7 +/- 3br> higher than 2010 for the YRD. Overall, our emission estimates were significantly smaller (9.5 than those estimated (0.179 mg m(-2) s(-1)) from the EDGAR emission database. |
BibTeX:
@article{hu18c,
author = {Hu, Cheng and Liu, Shoudong and Wang, Yongwei and Zhang, Mi and Xiao, Wei and Wang, Wei and Xu, Jiaping},
title = {Anthropogenic CO2 emissions from a megacity in the Yangtze River Delta of China},
journal = {ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH},
year = {2018},
volume = {25},
number = {23, SI},
pages = {23157-23169},
doi = {{10.1007/s11356-018-2325-3}}
}
|
| Humpage N, Boesch H, Palmer PI, Vick A, Parr-Burman P, Wells M, Pearson D, Strachan J and Bezawada N ({2018}), "GreenHouse gas Observations of the Stratosphere and Troposphere (GHOST): an airborne shortwave-infrared spectrometer for remote sensing of greenhouse gases", ATMOSPHERIC MEASUREMENT TECHNIQUES., SEP 12, {2018}. Vol. {11}({9}), pp. {5199-5222}. |
| Abstract: GHOST is a novel, compact shortwave-infrared grating spectrometer, designed for remote sensing of tropospheric columns of greenhouse gases (GHGs) from an airborne platform. It observes solar radiation at medium to high spectral resolution (better than 0.3 nm), which has been reflected by the Earth's surface using similar methods to those used by polar-orbiting satellites such as the JAXA GOSAT mission, NASA's OCO-2, and the Copernicus Sentinel-5 Precursor. By using an original design comprising optical fibre inputs along with a single diffraction grating and detector array, GHOST is able to observe CO2 absorption bands centred around 1.61 and 2.06 mu m (the same wavelength regions used by OCO-2 and GOSAT) whilst simultaneously measuring CH4 absorption at 1.65 mu m (also observed by GOSAT) and CH4 and CO at 2.30 mu m (observed by Sentinel-5P). With emissions expected to become more concentrated towards city sources as the global population residing in urban areas increases, there emerges a clear requirement to bridge the spatial scale gap between small-scale urban emission sources and global-scale GHG variations. In addition to the benefits achieved in spatial coverage through being able to remotely sense GHG tropospheric columns from an aircraft, the overlapping spectral ranges and comparable spectral resolutions mean that GHOST has unique potential for providing validation opportunities for these platforms, particularly over the ocean, where ground-based validation measurements are not available. In this paper we provide an overview of the GHOST instrument, calibration, and data processing, demonstrating the instrument's performance and suitability for GHG remote sensing. We also report on the first GHG observations made by GHOST during its maiden science flights on board the NASA Global Hawk unmanned aerial vehicle, which took place over the eastern Pacific Ocean in March 2015 as part of the CAST/ATTREX joint Global Hawk flight campaign. |
BibTeX:
@article{humpage18a,
author = {Humpage, Neil and Boesch, Hartmut and Palmer, Paul I. and Vick, Andy and Parr-Burman, Phil and Wells, Martyn and Pearson, David and Strachan, Jonathan and Bezawada, Naidu},
title = {GreenHouse gas Observations of the Stratosphere and Troposphere (GHOST): an airborne shortwave-infrared spectrometer for remote sensing of greenhouse gases},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2018},
volume = {11},
number = {9},
pages = {5199-5222},
doi = {{10.5194/amt-11-5199-2018}}
}
|
| Hungershoefer K, Breon FM, Peylin P, Chevallier F, Rayner P, Klonecki A, Houweling S and Marshall J ({2010}), "Evaluation of various observing systems for the global monitoring of CO2 surface fluxes", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({21}), pp. 10503-10520. |
| Abstract: In the context of rising greenhouse gas concentrations, and the potential feedbacks between climate and the carbon cycle, there is an urgent need to monitor the exchanges of carbon between the atmosphere and both the ocean and the land surfaces. In the so-called top-down approach, the surface fluxes of CO2 are inverted from the observed spatial and temporal concentration gradients. The concentrations of CO2 are measured in-situ at a number of surface stations unevenly distributed over the Earth while several satellite missions may be used to provide a dense and better-distributed set of observations to complement this network. In this paper, we compare the ability of different CO2 concentration observing systems to constrain surface fluxes. The various systems are based on realistic scenarios of sampling and precision for satellite and in-situ measurements. It is shown that satellite measurements based on the differential absorption technique (such as those of SCIAMACHY, GOSAT or OCO) provide more information than the thermal infrared observations (such as those of AIRS or IASI). The OCO observations will provide significantly better information than those of GOSAT. A CO2 monitoring mission based on an active (lidar) technique could potentially provide an even better constraint. This constraint can also be realized with the very dense surface network that could be built with the same funding as that of the active satellite mission. Despite the large uncertainty reductions on the surface fluxes that may be expected from these various observing systems, these reductions are still insufficient to reach the highly demanding requirements for the monitoring of anthropogenic emissions of CO2 or the oceanic fluxes at a spatial scale smaller than that of oceanic basins. The scientific objective of these observing system should therefore focus on the fluxes linked to vegetation and land ecosystem dynamics. |
BibTeX:
@article{hungershoefer10a,
author = {Hungershoefer, K. and Breon, F. -M. and Peylin, P. and Chevallier, F. and Rayner, P. and Klonecki, A. and Houweling, S. and Marshall, J.},
title = {Evaluation of various observing systems for the global monitoring of CO2 surface fluxes},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2010},
volume = {10},
number = {21},
pages = {10503--10520},
doi = {10.5194/acp-10-10503-2010}
}
|
| Huntzinger DN, Gourdji SM, Mueller KL and Michalak AM ({2011}), "The utility of continuous atmospheric measurements for identifying biospheric CO2 flux variability", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 23, {2011}. Vol. {116} |
| Abstract: Motivated by the need to improve the modeling of land-atmosphere carbon exchange, this study examines the extent to which continuous atmospheric carbon dioxide (CO2) observations can be used to evaluate flux variability at regional scales. The net ecosystem exchange estimates of four terrestrial biospheric models (TBMs) are used to represent plausible scenarios of surface flux distributions, which are compared in terms of their resulting atmospheric signals. The analysis focuses on North America using the nine towers of the continuous observation network that were operational in 2004. Four test cases are designed to isolate the influence on the atmospheric observations of (1) overall flux differences, (2) magnitude differences in flux across large regions, (3) differences in the flux patterns within ecoregions, and (4) flux variability in the near and far field of observation locations. The CO2 signals generated from the different representations of surface flux distribution are compared using a Chi-square test of variance. Differences found to be significant are driven primarily by differences in flux magnitude over large scales, and the fine-scale (primarily temporal) variability of fluxes within the near field of observation locations. Differences in the spatial distribution of fluxes within individual ecoregions, on the other hand, do not translate into significant differences in the observed signals at the towers. Thus, given the types of variation in flux represented by the four TBMs, the atmospheric data may be most informative in the evaluation of aggregated fluxes over large spatial scales (e. g., ecoregions), as well as in the improvement of how the diurnal cycle of fluxes is represented in TBMs, particularly in areas close to tower locations. |
BibTeX:
@article{huntzinger11a,
author = {Huntzinger, Deborah N. and Gourdji, Sharon M. and Mueller, Kimberly L. and Michalak, Anna M.},
title = {The utility of continuous atmospheric measurements for identifying biospheric CO2 flux variability},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2010JD015048}
}
|
| Huntzinger DN, Gourdji SM, Mueller KL and Michalak AM ({2011}), "A systematic approach for comparing modeled biospheric carbon fluxes across regional scales", BIOGEOSCIENCES. Vol. {8}({6}), pp. 1579-1593. |
| Abstract: Given the large differences between biospheric model estimates of regional carbon exchange, there is a need to understand and reconcile the predicted spatial variability of fluxes across models. This paper presents a set of quantitative tools that can be applied to systematically compare flux estimates despite the inherent differences in model formulation. The presented methods include variogram analysis, variable selection, and geostatistical regression. These methods are evaluated in terms of their ability to assess and identify differences in spatial variability in flux estimates across North America among a small subset of models, as well as differences in the environmental drivers that best explain the spatial variability of predicted fluxes. The examined models are the Simple Biosphere (SiB 3.0), Carnegie Ames Stanford Approach (CASA), and CASA coupled with the Global Fire Emissions Database (CASA GFEDv2), and the analyses are performed on model-predicted net ecosystem exchange, gross primary production, and ecosystem respiration. Variogram analysis reveals consistent seasonal differences in spatial variability among modeled fluxes at a 1 degrees x 1 degrees spatial resolution. However, significant differences are observed in the overall magnitude of the carbon flux spatial variability across models, in both net ecosystem exchange and component fluxes. Results of the variable selection and geostatistical regression analyses suggest fundamental differences between the models in terms of the factors that explain the spatial variability of predicted flux. For example, carbon flux is more strongly correlated with percent land cover in CASA GFEDv2 than in SiB or CASA. Some of the differences in spatial patterns of estimated flux can be linked back to differences in model formulation, and would have been difficult to identify simply by comparing net fluxes between models. Overall, the systematic approach presented here provides a set of tools for comparing predicted grid-scale fluxes across models, a task that has historically been difficult unless standardized forcing data were prescribed, or a detailed sensitivity analysis performed. |
BibTeX:
@article{huntzinger11b,
author = {Huntzinger, D. N. and Gourdji, S. M. and Mueller, K. L. and Michalak, A. M.},
title = {A systematic approach for comparing modeled biospheric carbon fluxes across regional scales},
journal = {BIOGEOSCIENCES},
year = {2011},
volume = {8},
number = {6},
pages = {1579--1593},
doi = {10.5194/bg-8-1579-2011}
}
|
| Hutjes RWA, Vellinga US, Gioli B and Miglietta F ({2010}), "Dis-aggregation of airborne flux measurements using footprint analysis", AGRICULTURAL AND FOREST METEOROLOGY., JUL 15, {2010}. Vol. {150}({7-8}), pp. 966-983. |
| Abstract: Aircraft measurements of turbulent fluxes are generally being made with the objective to obtain an estimate of regional exchanges between land surface and atmosphere, to investigate the spatial variability of these fluxes, but also to learn something about the fluxes from some or all of the land cover types that make up the landscape. In this study we develop a method addressing this last objective, an approach to disentangle blended fluxes from a landscape into the component fluxes emanating from the various land cover classes making up that landscape. The method relies on using a footprint model to determine which part of the landscape the airborne flux observation refers to, using a high resolution land cover map to determine the fractional covers of the various land cover classes within that footprint, and finally using multiple linear regression on many such flux/fractional cover data records to estimate the component fluxes. The method is developed in the context of three case studies of increasing complexity and the analysis covers three scalar fluxes: sensible and latent heat fluxes and carbon dioxide flux, as well as the momentum flux. A basic assumption under the dis-aggregation method is that the composite flux, i.e. the landscape flux, is a linear average of the component fluxes, i.e. the fluxes from the various land elements. We test and justify this assumption by comparing linear averages of component fluxes in simple `binary landscapes', weighted by their relative area, with directly aircraft observed fluxes. In all case studies dis-aggregation of mixed values for fluxes from heterogeneous areas into component land cover class specific fluxes is feasible using robust least squares regression, both in simple binary `landscapes' and in more complex cases. Both the differences between land cover classes and the differences between synoptic conditions can be resolved, for those land cover classes that make up sufficiently large fractions of the landscape. The regression F-statistic and the closely associated p-values are good indicators for this latter prerequisite and for other sources of uncertainty in the dis-aggregated flux estimates that render it meaningful or not. An analysis of the effect of various sources of errors in input data, footprint estimates and of skewed land cover class distributions is presented. A validation of flux estimates obtained through the dis-aggregation method against independent ground data proved satisfactorily. Recommendations for the use of the method are given as are suggestions for further development. (C) 2010 Elsevier B.V. All rights reserved. |
BibTeX:
@article{hutjes10a,
author = {Hutjes, R. W. A. and Vellinga, U. S. and Gioli, B. and Miglietta, F.},
title = {Dis-aggregation of airborne flux measurements using footprint analysis},
journal = {AGRICULTURAL AND FOREST METEOROLOGY},
year = {2010},
volume = {150},
number = {7-8},
pages = {966--983},
doi = {10.1016/j.agrformet.2010.03.004}
}
|
| Hutjes R, Bosveld F, Dolman A, Houweling S, Peters W, Meesters A, Moene A, Neubert R, KleinBaltink H, Unal C and others (2012), "Titel rapport AN ASSESSMENT OF THE POTENTIAL FOR ATMOSPHERIC EMISSION VERIFICATION IN THE NETHERLANDS". Thesis at: Wageningen University and Research Centre. |
BibTeX:
@techreport{hutjes12a,
author = {Hutjes, RWA and Bosveld, FC and Dolman, AJ and Houweling, S and Peters, W and Meesters, AGCA and Moene, A and Neubert, REM and KleinBaltink, H and Unal, CMH and others},
title = {Titel rapport AN ASSESSMENT OF THE POTENTIAL FOR ATMOSPHERIC EMISSION VERIFICATION IN THE NETHERLANDS},
school = {Wageningen University and Research Centre},
year = {2012},
url = {https://www.researchgate.net/profile/Ronald_Hutjes/publication/283419017_An_assessment_of_the_potential_for_atmospheric_emission_verification_in_The_Netherlands/links/5640741a08ae34e98c4e8221/An-assessment-of-the-potential-for-atmospheric-emission-verification-in-The-Netherlands.pdf}
}
|
| Isaac LID, Lauvaux T, Davis KJ, Miles NL, Richardson SJ, Jacobson AR and Andrews AE ({2014}), "Model-data comparison of MCI field campaign atmospheric CO2 mole fractions", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., SEP 16, {2014}. Vol. {119}({17}) |
| Abstract: Atmospheric transport model errors are a major contributor to uncertainty in CO2 inverse flux estimates. Our study compares CO2 mole fraction observations from the North American Carbon Program Mid-Continental Intensive (MCI) field campaign and modeled mole fractions from two atmospheric transport models: the global Transport Model 5 from NOAA's CarbonTracker system and the mesoscale Weather Research and Forecasting model. Both models are coupled to identical CO2 fluxes and lateral boundary conditions from CarbonTracker (CT2009 release). Statistical analyses were performed for two periods of 2007 using observed daily daytime average mole fractions of CO2 to test the ability of these models to reproduce the observations and to infer possible causes of the discrepancies. TM5-CT2009 overestimates midsummer planetary boundary layer CO2 for sites in the U. S. corn belt by 10 ppm. Weather Research and Forecasting (WRF)-CT2009 estimates diverge from the observations with similar magnitudes, but the signs of the differences vary from site to site. The modeled mole fractions are highly correlated with the observed seasonal cycle (r >= 0.7) but less correlated in the growing season, where weather-related changes in CO2 dominate the observed variability. Spatial correlations in residuals from TM5-CT2009 are higher than WRF-CT2009 perhaps due to TM5's coarse horizontal resolution and shallow vertical mixing. Vertical mixing appears to have influenced CO2 residuals from both models. TM5-CT2009 has relatively weak vertical mixing near the surface limiting the connection between local CO2 surface fluxes and boundary layer. WRF-CT2009 has stronger vertical mixing that may increase the connections between local surface fluxes and the boundary layer. |
BibTeX:
@article{isaac14a,
author = {Isaac, Liza I. Diaz and Lauvaux, Thomas and Davis, Kenneth J. and Miles, Natasha L. and Richardson, Scott J. and Jacobson, Andrew R. and Andrews, Arlyn E.},
title = {Model-data comparison of MCI field campaign atmospheric CO2 mole fractions},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2014},
volume = {119},
number = {17},
doi = {10.1002/2014JD021593}
}
|
| Ishidoya S, Aoki S, Goto D, Nakazawa T, Taguchi S and Patra PK ({2012}), "Time and space variations of the O-2/N-2 ratio in the troposphere over Japan and estimation of the global CO2 budget for the period 2000-2010", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {64} |
| Abstract: Systematic measurements of the atmospheric O-2/N-2 ratio have been made using aircraft and ground-based stations in Japan since 1999. The observed seasonal cycles of the O-2/N-2 ratio and atmospheric potential oxygen (APO) vary almost in opposite phase to that of the CO2 concentration at all altitudes, and their amplitudes and phases are generally reduced and delayed, respectively, with increasing altitude. Simulations of APO using two atmospheric transport models reproduce general features of the observed seasonal cycle, but both models fail to reproduce the phase at an altitude ranging from 8 km to the tropopause. By analysing the observed secular trends of APO and CO2 concentration, and assuming a global net oceanic O-2 outgassing of 0.2 +/- 0.5 GtC yr(-1), we estimate global average terrestrial biospheric and oceanic CO2 uptake for the period 2000-2010 to be 1.0 +/- 0.8 and 2.5 +/- 0.7 GtC yr(-1), respectively. |
BibTeX:
@article{ishidoya12a,
author = {Ishidoya, Shigeyuki and Aoki, Shuji and Goto, Daisuke and Nakazawa, Takakiyo and Taguchi, Shoichi and Patra, Prabir K.},
title = {Time and space variations of the O-2/N-2 ratio in the troposphere over Japan and estimation of the global CO2 budget for the period 2000-2010},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2012},
volume = {64},
doi = {10.3402/tellusb.v64i0.18964}
}
|
| Ishii M, Feely RA, Rodgers KB, Park GH, Wanninkhof R, Sasano D, Sugimoto H, Cosca CE, Nakaoka S, Telszewski M, Nojiri Y, Fletcher SEM, Niwa Y, Patra PK, Valsala V, Nakano H, Lima I, Doney SC, Buitenhuis ET, Aumont O, Dunne JP, Lenton A and Takahashi T ({2014}), "Air-sea CO2 flux in the Pacific Ocean for the period 1990-2009", BIOGEOSCIENCES. Vol. {11}({3}), pp. 709-734. |
| Abstract: Air-sea CO2 fluxes over the Pacific Ocean are known to be characterized by coherent large-scale structures that reflect not only ocean subduction and upwelling patterns, but also the combined effects of wind-driven gas exchange and biology. On the largest scales, a large net CO2 influx into the extratropics is associated with a robust seasonal cycle, and a large net CO2 efflux from the tropics is associated with substantial interannual variability. In this work, we have synthesized estimates of the net air-sea CO2 flux from a variety of products, drawing upon a variety of approaches in three sub-basins of the Pacific Ocean, i. e., the North Pacific extratropics (18-66 degrees N), the tropical Pacific (18 degrees S-18 degrees N), and the South Pacific extratropics (44.5-18 degrees S). These approaches include those based on the measurements of CO2 partial pressure in surface seawater (pCO(2)sw), inversions of ocean-interior CO2 data, forward ocean biogeochemistry models embedded in the ocean general circulation models (OBGCMs), a model with assimilation of pCO(2)sw data, and inversions of atmospheric CO2 measurements. Long-term means, interannual variations and mean seasonal variations of the regionally integrated fluxes were compared in each of the sub-basins over the last two decades, spanning the period from 1990 through 2009. A simple average of the long-term mean fluxes obtained with surface water pCO(2) diagnostics and those obtained with ocean-interior CO2 inversions are -0.47 +/- 0.13 Pg Cyr(-1) in the North Pacific extratropics, +/- 0.44 +/- 0.14 Pg Cyr(-1) in the tropical Pacific, and -0.37 +/- 0.08 Pg C yr(-1) in the South Pacific extratropics, where positive fluxes are into the atmosphere. This suggests that approximately half of the CO2 taken up over the North and South Pacific extratropics is released back to the atmosphere from the tropical Pacific. These estimates of the regional fluxes are also supported by the estimates from OBGCMs after adding the riverine CO2 flux, i.e., -0.49 +/- 0.02 Pg Cyr(-1) in the North Pacific extratropics, +0.41 +/- 0.05 Pg Cyr(-1) in the tropical Pacific, and -0.39 +/- 0.11 Pg Cyr(-1) in the South Pacific extratropics. The estimates from the atmospheric CO2 inversions show large variations amongst different inversion systems, but their median fluxes are consistent with the estimates from climatological pCO(2)sw data and pCO(2)sw diagnostics. In the South Pacific extratropics, where CO2 variations in the surface and ocean interior are severely undersampled, the difference in the air-sea CO2 flux estimates between the diagnostic models and ocean-interior CO2 inversions is larger (0.18 Pg Cyr(-1)). The range of estimates from forward OBGCMs is also large (-0.19 to -0.72 Pg Cyr(-1)). Regarding interannual variability of air-sea CO2 fluxes, positive and negative anomalies are evident in the tropical Pacific during the cold and warm events of the El Nino-Southern Oscillation in the estimates from pCO(2)sw diagnostic models and from OBGCMs. They are consistent in phase with the Southern Oscillation Index, but the peak-to-peak amplitudes tend to be higher in OBGCMs (0.40 +/- 0.09 Pg Cyr(-1)) than in the diagnostic models (0.27 +/- 0.07 Pg Cyr(-1)). |
BibTeX:
@article{ishii14a,
author = {Ishii, M. and Feely, R. A. and Rodgers, K. B. and Park, G. -H. and Wanninkhof, R. and Sasano, D. and Sugimoto, H. and Cosca, C. E. and Nakaoka, S. and Telszewski, M. and Nojiri, Y. and Fletcher, S. E. Mikaloff and Niwa, Y. and Patra, P. K. and Valsala, V. and Nakano, H. and Lima, I. and Doney, S. C. and Buitenhuis, E. T. and Aumont, O. and Dunne, J. P. and Lenton, A. and Takahashi, T.},
title = {Air-sea CO2 flux in the Pacific Ocean for the period 1990-2009},
journal = {BIOGEOSCIENCES},
year = {2014},
volume = {11},
number = {3},
pages = {709--734},
doi = {10.5194/bg-11-709-2014}
}
|
| Ito A ({2011}), "Decadal Variability in the Terrestrial Carbon Budget Caused by the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation", JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN., OCT, {2011}. Vol. {89}({5}), pp. 441-454. |
| Abstract: The terrestrial carbon dioxide (CO2) budget interacts with the Earth's climate system on diurnal to centennial and longer time scales, making it critical for climatic prediction and stabilization. Atmospheric observations and global syntheses of CO2 data indicate that the terrestrial biosphere is one the major sources of interannual variability, but the underlying mechanisms operating on different time-scales and the potential impacts of this on future projections remain unclear. Here it is shown that the El Nino and Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) regime affect temporal variability in the terrestrial carbon budget with different time scales. The terrestrial carbon budget, estimated using a process-based model (VISIT) for the period 1910-2005, was correlated with the indices of PDO, AMO, and ENSO with various smoothing periods and lag lengths. ENSO showed the highest short-term correlation, corresponding to interannual terrestrial variability, whereas PDO and AMO had higher correlations at the decadal time scale. Such correlations with the meteorological regimes occurred heterogeneously over the land surface. Tin; study suggests that long-term monitoring is needed to elucidate the temporal variability, and that decadal predictability of climate and terrestrial models should be improved further. |
BibTeX:
@article{ito11a,
author = {Ito, Akihiko},
title = {Decadal Variability in the Terrestrial Carbon Budget Caused by the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation},
journal = {JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN},
year = {2011},
volume = {89},
number = {5},
pages = {441--454},
doi = {10.2151/jmsj.2011-503}
}
|
| Jacob DJ, Turner AJ, Maasakkers JD, Sheng J, Sun K, Liu X, Chance K, Aben I, McKeever J and Frankenberg C ({2016}), "Satellite observations of atmospheric methane and their value for quantifying methane emissions", ATMOSPHERIC CHEMISTRY AND PHYSICS., NOV 18, {2016}. Vol. {16}({22}), pp. 14371-14396. |
| Abstract: Methane is a greenhouse gas emitted by a range of natural and anthropogenic sources. Atmospheric methane has been measured continuously from space since 2003, and new instruments are planned for launch in the near future that will greatly expand the capabilities of space-based observations. We review the value of current, future, and proposed satellite observations to better quantify and understand methane emissions through inverse analyses, from the global scale down to the scale of point sources and in combination with suborbital (surface and aircraft) data. Current global observations from Greenhouse Gases Observing Satellite (GOSAT) are of high quality but have sparse spatial coverage. They can quantify methane emissions on a regional scale (100-1000 km) through multiyear averaging. The Tropospheric Monitoring Instrument (TROPOMI), to be launched in 2017, is expected to quantify daily emissions on the regional scale and will also effectively detect large point sources. A different observing strategy by GHGSat (launched in June 2016) is to target limited viewing domains with very fine pixel resolution in order to detect a wide range of methane point sources. Geostationary observation of methane, still in the proposal stage, will have the unique capability of mapping source regions with high resolution, detecting transient ``super-emitter'' point sources and resolving diurnal variation of emissions from sources such as wetlands and manure. Exploiting these rapidly expanding satellite measurement capabilities to quantify methane emissions requires a parallel effort to construct high-quality spatially and sectorally resolved emission inventories. Partnership between top-down inverse analyses of atmospheric data and bottom-up construction of emission inventories is crucial to better understanding methane emission processes and subsequently informing climate policy. |
BibTeX:
@article{jacob16a,
author = {Jacob, Daniel J. and Turner, Alexander J. and Maasakkers, Joannes D. and Sheng, Jianxiong and Sun, Kang and Liu, Xiong and Chance, Kelly and Aben, Ilse and McKeever, Jason and Frankenberg, Christian},
title = {Satellite observations of atmospheric methane and their value for quantifying methane emissions},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2016},
volume = {16},
number = {22},
pages = {14371--14396},
doi = {10.5194/acp-16-14371-2016}
}
|
| Jamroensan A (2013), "Improving bottom-up and top-down estimates of carbon fluxes in the Midwestern USA". Thesis at: The University of Iowa. |
BibTeX:
@phdthesis{jamroensan13a,
author = {Jamroensan, Aditsuda},
title = {Improving bottom-up and top-down estimates of carbon fluxes in the Midwestern USA},
school = {The University of Iowa},
year = {2013},
url = {http://search.proquest.com/openview/0101c608a315817af6e44eee3c2c3053/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Jiang F, Wang HW, Chen JM, Zhou LX, Ju WM, Ding AJ, Liu LX and Peters W ({2013}), "Nested atmospheric inversion for the terrestrial carbon sources and sinks in China", BIOGEOSCIENCES. Vol. {10}({8}), pp. 5311-5324. |
| Abstract: In this study, we establish a nested atmospheric inversion system with a focus on China using the Bayesian method. The global surface is separated into 43 regions based on the 22 TransCom large regions, with 13 small regions in China. Monthly CO2 concentrations from 130 GlobalView sites and 3 additional China sites are used in this system. The core component of this system is an atmospheric transport matrix, which is created using the TM5 model with a horizontal resolution of 3 degrees x 2 degrees. The net carbon fluxes over the 43 global land and ocean regions are inverted for the period from 2002 to 2008. The inverted global terrestrial carbon sinks mainly occur in boreal Asia, South and Southeast Asia, eastern America and southern South America. Most China areas appear to be carbon sinks, with strongest carbon sinks located in Northeast China. From 2002 to 2008, the global terrestrial carbon sink has an increasing trend, with the lowest carbon sink in 2002. The inter-annual variation (IAV) of the land sinks shows remarkable correlation with the El Nino Southern Oscillation (ENSO). The terrestrial carbon sinks in China also show an increasing trend. However, the IAV in China is not the same as that of the globe. There is relatively stronger land sink in 2002, lowest sink in 2006, and strongest sink in 2007 in China. This IAV could be reasonably explained with the IAVs of temperature and precipitation in China. The mean global and China terrestrial carbon sinks over the period 2002-2008 are -3.20 +/- 0.63 and -0.28 +/- 0.18 PgC yr(-1), respectively. Considering the carbon emissions in the form of reactive biogenic volatile organic compounds (BVOCs) and from the import of wood and food, we further estimate that China's land sink is about -0.31 PgC yr(-1). |
BibTeX:
@article{jiang13a,
author = {Jiang, F. and Wang, H. W. and Chen, J. M. and Zhou, L. X. and Ju, W. M. and Ding, A. J. and Liu, L. X. and Peters, W.},
title = {Nested atmospheric inversion for the terrestrial carbon sources and sinks in China},
journal = {BIOGEOSCIENCES},
year = {2013},
volume = {10},
number = {8},
pages = {5311--5324},
doi = {10.5194/bg-10-5311-2013}
}
|
| Jiang F, Chen JM, Zhou L, Ju W, Zhang H, Machida T, Ciais P, Peters W, Wang H, Chen B, Liu L, Zhang C, Matsueda H and Sawa Y ({2016}), "A comprehensive estimate of recent carbon sinks in China using both top-down and bottom-up approaches", SCIENTIFIC REPORTS., FEB 29, {2016}. Vol. {6} |
| Abstract: Atmospheric inversions use measurements of atmospheric CO2 gradients to constrain regional surface fluxes. Current inversions indicate a net terrestrial CO2 sink in China between 0.16 and 0.35 PgC/yr. The uncertainty of these estimates is as large as the mean because the atmospheric network historically contained only one high altitude station in China. Here, we revisit the calculation of the terrestrial CO2 flux in China, excluding emissions from fossil fuel burning and cement production, by using two inversions with three new CO2 monitoring stations in China as well as aircraft observations over Asia. We estimate a net terrestrial CO2 uptake of 0.39-0.51 PgC/yr with a mean of 0.45 PgC/yr in 2006-2009. After considering the lateral transport of carbon in air and water and international trade, the annual mean carbon sink is adjusted to 0.35 PgC/yr. To evaluate this top-down estimate, we constructed an independent bottom-up estimate based on ecosystem data, and giving a net land sink of 0.33 PgC/yr. This demonstrates closure between the top-down and bottom-up estimates. Both top-down and bottom-up estimates give a higher carbon sink than previous estimates made for the 1980s and 1990s, suggesting a trend towards increased uptake by land ecosystems in China. |
BibTeX:
@article{jiang16a,
author = {Jiang, Fei and Chen, Jing M. and Zhou, Lingxi and Ju, Weimin and Zhang, Huifang and Machida, Toshinobu and Ciais, Philippe and Peters, Wouter and Wang, Hengmao and Chen, Baozhang and Liu, Lixin and Zhang, Chunhua and Matsueda, Hidekazu and Sawa, Yousuke},
title = {A comprehensive estimate of recent carbon sinks in China using both top-down and bottom-up approaches},
journal = {SCIENTIFIC REPORTS},
year = {2016},
volume = {6},
doi = {10.1038/srep22130}
}
|
| Jiang X, Crisp D, Olsen ET, Kulawik SS, Miller CE, Pagano TS, Liang M and Yung YL (2016), "CO2 annual and semiannual cycles from multiple satellite retrievals and models", Earth and Space Science. Vol. 3(2), pp. 78-87. |
BibTeX:
@article{jiang16b,
author = {Jiang, Xun and Crisp, David and Olsen, Edward T and Kulawik, Susan S and Miller, Charles E and Pagano, Thomas S and Liang, Maochang and Yung, Yuk L},
title = {CO2 annual and semiannual cycles from multiple satellite retrievals and models},
journal = {Earth and Space Science},
year = {2016},
volume = {3},
number = {2},
pages = {78--87},
doi = {10.1002/2014EA000045/full}
}
|
| Jing Y, Shi J, Wang T and Sussmann R ({2014}), "Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution", ATMOSPHERE., DEC, {2014}. Vol. {5}({4}), pp. 870-888. |
| Abstract: Satellite measurements of the spatiotemporal distributions of atmospheric CO2 concentrations are a key component for better understanding global carbon cycle characteristics. Currently, several satellite instruments such as the Greenhouse gases Observing SATellite (GOSAT), SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY), and Orbiting Carbon Observatory-2 can be used to measure CO2 column-averaged dry air mole fractions. However, because of cloud effects, a single satellite can only provide limited CO2 data, resulting in significant uncertainty in the characterization of the spatiotemporal distribution of atmospheric CO2 concentrations. In this study, a new physical data fusion technique is proposed to combine the GOSAT and SCIAMACHY measurements. On the basis of the fused dataset, a gap-filling method developed by modeling the spatial correlation structures of CO2 concentrations is presented with the goal of generating global land CO2 distribution maps with high spatiotemporal resolution. The results show that, compared with the single satellite dataset (i.e., GOSAT or SCIAMACHY), the global spatial coverage of the fused dataset is significantly increased (reaching up to approximately 20, and the temporal resolution is improved by two or three times. The spatial coverage and monthly variations of the generated global CO2 distributions are also investigated. Comparisons with ground-based Total Carbon Column Observing Network (TCCON) measurements reveal that CO2 distributions based on the gap-filling method show good agreement with TCCON records despite some biases. These results demonstrate that the fused dataset as well as the gap-filling method are rather effective to generate global CO2 distribution with high accuracies and high spatiotemporal resolution. |
BibTeX:
@article{jing14a,
author = {Jing, Yingying and Shi, Jiancheng and Wang, Tianxing and Sussmann, Ralf},
title = {Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution},
journal = {ATMOSPHERE},
year = {2014},
volume = {5},
number = {4},
pages = {870--888},
doi = {10.3390/atmos5040870}
}
|
| Jing Y, Shi J and Wang T ({2014}), "FUSION OF SPACE-BASED CO2 PRODUCTS AND ITS COMPARISON WITH OTHER AVAILABLE CO2 ESTIMATES", In 2014 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS). , pp. 2363-2366. |
| Abstract: Currently, ascertaining and quantifying the global distribution of carbon dioxide from space-based measurements are greatly valuable for understanding the causes of global warming and predicting the tendency of climate change. Nevertheless, the number of valid XCO2 data points from a single space-based sensor is generally limited on the earth. Based on this problem, a fused XCO2 dataset is used to generate a continuous spatio-temporal distribution of global CO2 concentration by combining GOSAT with SCIAMACHY in this study. And this dataset is also compared with a data assimilation system Carbon Tracker as well as ground-based TCCON sites. The results reveal that the spatial coverage of the fused data is wider than individual space-based XCO2 measurements (GOSAT or SCIAMCHY) on the global scale. Meanwhile, compared to that of GOSAT or SCIAMACHY, the correlation between the fused data and Carbon Tracker is relatively better. In addition, the fused data show a good agreement with CO2 retrieval of ACOS and BESD as well as that of TCCON sites although a little biases exist. |
BibTeX:
@inproceedings{jing14b,
author = {Jing, Yingying and Shi, Jiancheng and Wang, Tianxing},
title = {FUSION OF SPACE-BASED CO2 PRODUCTS AND ITS COMPARISON WITH OTHER AVAILABLE CO2 ESTIMATES},
booktitle = {2014 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS)},
year = {2014},
pages = {2363--2366},
note = {IEEE Joint International Geoscience and Remote Sensing Symposium (IGARSS) / 35th Canadian Symposium on Remote Sensing, Quebec City, CANADA, JUL 13-18, 2014},
doi = {10.1109/IGARSS.2014.6946946}
}
|
| Jing Y, Wang T and Shi J ({2014}), "TOWARD ACCURATE XCO2 LEVEL 2 MEASUREMENTS BY COMBINING DIFFERENT CO2 RETRIEVALS FROM GOSAT AND SCIAMACHY", In 2014 THIRD INTERNATIONAL WORKSHOP ON EARTH OBSERVATION AND REMOTE SENSING APPLICATIONS (EORSA 2014). |
| Abstract: Carbon dioxide (CO2) is one of the most important anthropogenic greenhouse gases causing global warming. Although various space-based observations have been used to derive and identify regional and global distribution of CO2 source and sink, uncertainties and biases are still subsistent. A high spatial and temporal resolution is important to remove the CO2 uncertainties and biases. In this study, an improved ensemble median algorithm is developed by fully accounting for the variation of XCO2 on synoptic timescales. Based on this, XCO2 data sets from the improved method and EMMA are compared in terms of their spatiotemporal distributions and correlations. Meanwhile, XCO2 measurements from three TCCON sites are used to compare with these two datasets. The results reveal that although there is a good correlation between the XCO2 from improved method and that of EMMA at annual scale, large discrepancies can be still detected at most places over the world. It seems that a higher time resolution is necessary to remove the outliers. In addition, the season cycle of the two methods is generally in agreement with ground measurements. However, our improved method shows less divergence compared to that of EMMA at three ground sites. To some extent, these results proved the effectiveness of our new method and thus demonstrated the necessity for refining the Level 2 XCO2 measurements at a shorter time averaging period. |
BibTeX:
@inproceedings{jing14c,
author = {Jing, Yingying and Wang, Tianxing and Shi, Jiancheng},
editor = {Weng, Q and Gamba, P and Xian, G and Wang, G and Zhu, J},
title = {TOWARD ACCURATE XCO2 LEVEL 2 MEASUREMENTS BY COMBINING DIFFERENT CO2 RETRIEVALS FROM GOSAT AND SCIAMACHY},
booktitle = {2014 THIRD INTERNATIONAL WORKSHOP ON EARTH OBSERVATION AND REMOTE SENSING APPLICATIONS (EORSA 2014)},
year = {2014},
note = {3rd International Workshop on Earth Observation and Remote Sensing Applications (EORSA), Changsha, PEOPLES R CHINA, JUN 11-14, 2014}
}
|
| Jing Y, Shi J and Wang T ({2015}), "EVALUATION AND COMPARISON OF ATMOSPHERIC CO2 CONCENTRATIONS FROM MODELS AND SATELLITE RETRIEVALS", In 2015 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS). , pp. 2202-2205. |
| Abstract: In recent years, global warming caused by increased atmospheric CO2 has greatly drawn widespread attention from the public. Although satellite observations and model-simulation offer us two effective approaches to monitor and assess the global atmospheric CO2, quantification of the differences between these two different CO2 data is not fully investigated yet. In this paper, these CO2 products including satellite observations and model-simulation are inter-compared in terms of magnitude and their spatiotemporal distributions. The results reveal that these CO2 data from different data source show a good agreement all over the world, whereas many discrepancies still exist between satellite observations and model-simulation, especially in the Northern Sphere. |
BibTeX:
@inproceedings{jing15a,
author = {Jing, Yingying and Shi, Jiancheng and Wang, Tianxing},
title = {EVALUATION AND COMPARISON OF ATMOSPHERIC CO2 CONCENTRATIONS FROM MODELS AND SATELLITE RETRIEVALS},
booktitle = {2015 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS)},
year = {2015},
pages = {2202--2205},
note = {IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, ITALY, JUL 26-31, 2015}
}
|
| Jing Y, Wang T, Zhang P, Chen L, Xu N and Ma Y (2018), "Global Atmospheric CO2 Concentrations Simulated by GEOS-Chem: Comparison with GOSAT, Carbon Tracker and Ground-Based Measurements", Atmosphere. Vol. 9(5), pp. 175. |
BibTeX:
@article{jing18a,
author = {Jing, Yingying and Wang, Tianxing and Zhang, Peng and Chen, Lin and Xu, Na and Ma, Ya},
title = {Global Atmospheric CO2 Concentrations Simulated by GEOS-Chem: Comparison with GOSAT, Carbon Tracker and Ground-Based Measurements},
journal = {Atmosphere},
year = {2018},
volume = {9},
number = {5},
pages = {175},
url = {https://www.mdpi.com/2073-4433/9/5/175/htm}
}
|
| Jones LA, Kimball JS, Reichle RH, Madani N, Glassy J, Ardizzone JV, Colliander A, Cleverly J, Desai AR, Eamus D, Euskirchen ES, Hutley L, Macfarlane C and Scott RL ({2017}), "The SMAP Level 4 Carbon Product for Monitoring Ecosystem Land-Atmosphere CO2 Exchange", IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING., NOV, {2017}. Vol. {55}({11}), pp. 6517-6532. |
| Abstract: The National Aeronautics and Space Administration's Soil Moisture Active Passive (SMAP) mission Level 4 Carbon (L4C) product provides model estimates of the Net Ecosystem CO2 exchange (NEE) incorporating SMAP soil moisture information. The L4C product includes NEE, computed as total ecosystem respiration less gross photosynthesis, at a daily time step posted to a 9-km global grid by plant functional type. Component carbon fluxes, surface soil organic carbon stocks, underlying environmental constraints, and detailed uncertainty metrics are also included. The L4C model is driven by the SMAP Level 4 Soil Moisture data assimilation product, with additional inputs from the Goddard Earth Observing System, Version 5 weather analysis, and Moderate Resolution Imaging Spectroradiometer satellite vegetation data. The L4C data record extends from March 31, 2015 to present with ongoing production and 8-12 day latency. Comparisons against concurrent global CO2 eddy flux tower measurements, satellite solar-induced canopy florescence, and other independent observation benchmarks show favorable L4C performance and accuracy, capturing the dynamic biosphere response to recent weather anomalies. Model experiments and L4C spatiotemporal variability were analyzed to understand the independent value of soil moisture and SMAP observations relative to other sources of input information. This analysis highlights the potential for microwave observations to inform models where soil moisture strongly controls land CO2 flux variability; however, skill improvement relative to flux towers is not yet discernable within the relatively short validation period. These results indicate that SMAP provides a unique and promising capability for monitoring the linked global terrestrial water and carbon cycles. |
BibTeX:
@article{jones17a,
author = {Jones, Lucas A. and Kimball, John S. and Reichle, Rolf H. and Madani, Nima and Glassy, Joe and Ardizzone, Joe V. and Colliander, Andreas and Cleverly, James and Desai, Ankur R. and Eamus, Derek and Euskirchen, Eugenie S. and Hutley, Lindsay and Macfarlane, Craig and Scott, Russell L.},
title = {The SMAP Level 4 Carbon Product for Monitoring Ecosystem Land-Atmosphere CO2 Exchange},
journal = {IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING},
year = {2017},
volume = {55},
number = {11},
pages = {6517--6532},
doi = {10.1109/TGRS.2017.2729343}
}
|
| Kanakidou M, Dameris M, Elbern H, Beekmann M, Konovalov IB, Nieradzik L, Strunk A and Krol MC ({2011}), "Synergistic Use of Retrieved Trace Constituent Distributions and Numerical Modelling", In REMOTE SENSING OF TROPOSPHERIC COMPOSITION FROM SPACE. , pp. 451-492. Springer. |
BibTeX:
@incollection{kanakidou11a,
author = {Kanakidou, Maria and Dameris, Martin and Elbern, Hendrik and Beekmann, Matthias and Konovalov, Igor B. and Nieradzik, Lars and Strunk, Achim and Krol, Maarten C.},
editor = {Burrows, JP and Platt, U and Borrell, P},
title = {Synergistic Use of Retrieved Trace Constituent Distributions and Numerical Modelling},
booktitle = {REMOTE SENSING OF TROPOSPHERIC COMPOSITION FROM SPACE},
publisher = {Springer},
year = {2011},
pages = {451--492},
doi = {10.1007/978-3-642-14791-3\_9}
}
|
| Kang J-S, Kalnay E, Liu J, Fung I, Miyoshi T and Ide K ({2011}), "``Variable localization'' in an ensemble Kalman filter: Application to the carbon cycle data assimilation", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 12, {2011}. Vol. {116} |
| Abstract: In ensemble Kalman filter, space localization is used to reduce the impact of long-distance sampling errors in the ensemble estimation of the forecast error covariance. When two variables are not physically correlated, their error covariance is still estimated by the ensemble and, therefore, it is dominated by sampling errors. We introduce a ``variable localization'' method, zeroing out such covariances between unrelated variables to the problem of assimilating carbon dioxide concentrations into a dynamical model using the local ensemble transform Kalman filter (LETKF) in an observing system simulation experiments (OSSE) framework. A system where meteorological and carbon variables are simultaneously assimilated is used to estimate surface carbon fluxes that are not directly observed. A range of covariance structures are explored for the LETKF, with emphasis on configurations allowing nonzero error covariance between carbon variables and the wind field, which affects transport of atmospheric CO2, but not between CO2 and the other meteorological variables. Such variable localization scheme zeroes out the background error covariance among prognostic variables that are not physically related, thus reducing sampling errors. Results from the identical twin experiments show that the performance in the estimation of surface carbon fluxes obtained using variable localization is much better than that using a standard full covariance approach. The relative improvement increases when the surface fluxes change with time and model error becomes significant. |
BibTeX:
@article{kang11a,
author = {Kang, Ji-Sun and Kalnay, Eugenia and Liu, Junjie and Fung, Inez and Miyoshi, Takemasa and Ide, Kayo},
title = {``Variable localization'' in an ensemble Kalman filter: Application to the carbon cycle data assimilation},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2010JD014673}
}
|
| Kang J-S, Kalnay E, Miyoshi T, Liu J and Fung I ({2012}), "Estimation of surface carbon fluxes with an advanced data assimilation methodology", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 19, {2012}. Vol. {117} |
| Abstract: We perform every 6 h a simultaneous data assimilation of surface CO2 fluxes and atmospheric CO2 concentrations along with meteorological variables using the Local Ensemble Transform Kalman Filter (LETKF) within an Observing System Simulation Experiments framework. In this paper, we focus on the impact of advanced variance inflation methods and vertical localization of column CO2 data on the analysis of CO2. With both additive inflation and adaptive multiplicative inflation, we are able to obtain encouraging multiseasonal analyses of surface CO2 fluxes in addition to atmospheric CO2 and meteorological analyses. Furthermore, we examine strategies for vertical localization in the assimilation of simulated CO2 from GOSAT that has nearly uniform sensitivity from the surface to the upper troposphere. Since atmospheric CO2 is forced by surface fluxes, its short-term variability should be largest near the surface. We take advantage of this by updating observed changes only into the lower tropospheric CO2 rather than into the full column. This results in a more accurate analysis of CO2 in terms of both RMS error and spatial patterns. Assimilating synthetic CO2 ground-based observations and CO2 retrievals from GOSAT and AIRS with the enhanced LETKF, we obtain an accurate estimation of the evolving surface fluxes even in the absence of any a priori information. We also test the system with a longer assimilation window and find that a short window with an efficient treatment for wind uncertainty is beneficial to flux inversion. Since this study assumes a perfect forecast model, future research will explore the impact of model errors. Citation: Kang, J.-S., E. Kalnay, T. Miyoshi, J. Liu, and I. Fung (2012), Estimation of surface carbon fluxes with an advanced data assimilation methodology, J. Geophys. Res., 117, D24101, doi: 10.1029/2012JD018259. |
BibTeX:
@article{kang12a,
author = {Kang, Ji-Sun and Kalnay, Eugenia and Miyoshi, Takemasa and Liu, Junjie and Fung, Inez},
title = {Estimation of surface carbon fluxes with an advanced data assimilation methodology},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2012},
volume = {117},
doi = {10.1029/2012JD018259}
}
|
| Karion A, Sweeney C, Tans P and Newberger T ({2010}), "AirCore: An Innovative Atmospheric Sampling System", JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY., NOV, {2010}. Vol. {27}({11}), pp. 1839-1853. |
| Abstract: This work describes the Air Core, a simple and innovative atmospheric sampling system. The AirCore used in this study is a 150-m-long stainless steel tube, open at one end and closed at the other, that relies on positive changes in ambient pressure for passive sampling of the atmosphere. The Air Core evacuates while ascending to a high altitude and collects a sample of the ambient air as it descends. It is sealed upon recovery and measured with a continuous analyzer for trace gas mole fraction. The Air Core tubing can be shaped into a variety of configurations to accommodate any sampling platform; for the testing done in this work it was shaped into a 0,75-m-diameter coil. Measurements of CO(2) and CH(4) mole fractions in laboratory tests indicate a repeatability and lack of bias to better than 0.07 ppm (one sigma) for CO, and 0.4 ppb for CH(4) under various conditions. Comparisons of AirCore data with flask data from aircraft flights indicate a standard deviation of differences of 0.3 ppm and 5 ppb for CO(2) and CH(4), respectively, with no apparent bias. Accounting for longitudinal mixing, the expected measurement resolution for CO2 is 110 m at sea level, 260 m at 8000 m. and 1500 m at 20 000 m ASL after 3 h of storage, decreasing to 170, 390, and 2300 m, after 12 h. Validation tests confirm that the AirCore is a robust sampling device for many species on a variety of platforms, including balloons, unmanned aerial vehicles (UAVs), and aircraft. |
BibTeX:
@article{karion10a,
author = {Karion, Anna and Sweeney, Colm and Tans, Pieter and Newberger, Timothy},
title = {AirCore: An Innovative Atmospheric Sampling System},
journal = {JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY},
year = {2010},
volume = {27},
number = {11},
pages = {1839--1853},
doi = {10.1175/2010JTECHA1448.1}
}
|
| Kassem II, Joshi P, Sigler V, Heckathorn S and Wang Q ({2008}), "Effect of Elevated CO2 and Drought on Soil Microbial Communities Associated with Andropogon gerardii", JOURNAL OF INTEGRATIVE PLANT BIOLOGY., NOV, {2008}. Vol. {50}({11}), pp. 1406-1415. |
| Abstract: Our understanding of the effects of elevated atmospheric CO2, singly and in combination with other environmental changes, on plant-soil interactions is incomplete. Elevated CO2 effects on C-4 plants, though smaller than on C-3 species, are mediated mostly via decreased stomatal conductance and thus water loss. Therefore, we characterized the interactive effect of elevated CO2 and drought on soil microbial communities associated with a dominant C-4 prairie grass, Andropogon gerardii Vitman. Elevated CO2 and drought both affected resources available to the soil microbial community. For example, elevated CO2 increased the soil C:N ratio and water content during drought, whereas drought alone decreased both. Drought significantly decreased soil microbial biomass. In contrast, elevated CO2 increased biomass while ameliorating biomass decreases that were induced under drought. Total and active direct bacterial counts and carbon substrate use (overall use and number of used sources) increased significantly under elevated CO2. Denaturing gradient gel electrophoresis analysis revealed that drought and elevated CO2, singly and combined, did not affect the soil bacteria community structure. We conclude that elevated CO2 alone increased bacterial abundance and microbial activity and carbon use, probably in response to increased root exudation. Elevated CO2 also limited drought-related impacts on microbial activity and biomass, which likely resulted from decreased plant water use under elevated CO2. These are among the first results showing that elevated CO2 and drought work in opposition to modulate plant-associated soil-bacteria responses, which should then influence soil resources and plant and ecosystem function. |
BibTeX:
@article{kassem08a,
author = {Kassem, Issmat I. and Joshi, Puneet and Sigler, Von and Heckathorn, Scott and Wang, Qi},
title = {Effect of Elevated CO2 and Drought on Soil Microbial Communities Associated with Andropogon gerardii},
journal = {JOURNAL OF INTEGRATIVE PLANT BIOLOGY},
year = {2008},
volume = {50},
number = {11},
pages = {1406--1415},
doi = {10.1111/j.1744-7909.2008.00752.x}
}
|
| Kavitha M and Nair PR ({2016}), "Region-dependent seasonal pattern of methane over Indian region as observed by SCIAMACHY", ATMOSPHERIC ENVIRONMENT., APR, {2016}. Vol. {131}, pp. 316-325. |
| Abstract: The column averaged mixing ratio of methane (XCH4) from SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on-board satellite ENVISAT has been used to study its regional pattern and seasonal cycle over Indian region for the period 2003-2009. XCH4 varies from 1740 to 1890 ppbv over Indian region with distinct spatial and temporal features. The peak values are observed in monsoon and post monsoon and minimum in winter months, except over southern Peninsular India which shows the distinctly different seasonal behavior with peak in October/November. The mean background level of XCH4 over Indian region is estimated as similar to 1795 ppbv. While regional patterns are strongly associated with livestock distribution, wetland emissions, including rice fields, the seasonal variations in XCH4 are predominantly associated with the rice cultivation as revealed by analysis of NDVI. (C) 2016 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{kavitha16a,
author = {Kavitha, M. and Nair, Prabha R.},
title = {Region-dependent seasonal pattern of methane over Indian region as observed by SCIAMACHY},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2016},
volume = {131},
pages = {316--325},
doi = {10.1016/j.atmosenv.2016.02.008}
}
|
| Kavitha M and Nair PR ({2017}), "SCIAMACHY observed changes in the column mixing ratio of methane over the Indian region and a comparison with global scenario", ATMOSPHERIC ENVIRONMENT., OCT, {2017}. Vol. {166}, pp. 454-466. |
| Abstract: The trends in the column averaged mixing ratio of methane (XCH4) over the Indian region during 2003 2009 periods were studied using the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) observations. Considering the sensor degradation, the trends were analyzed for 2003 to 2005 and 2006 to 2009 separately. Over India, the trend in XCH4 varied from 5.2 to 7.6 ppb per year after 2005, exhibiting a 2-4 fold increase compared to 2003-2005. While the increase over Northern parts of India is attributed to increasing CH4 emissions from rice cultivation and livestock population, those over Southern regions are due to increased oil and gas mining activities. A comparison of these trends with those over most of the hotspot regions over the globe revealed that those regions exhibited higher growth rates of XCH4 compared to Indian regions during 2006-2009. The seasonal patterns of XCH4 and near-surface CH4 at selected global network stations were also examined in detail. This analysis revealed hemispheric difference and varying seasonal patterns suggesting the inhomogeneous vertical distribution of CH4. The observed differences in the seasonal patterns of near-surface CH4 and XCH4 suggest that the surface emissions need not replicate at higher altitudes due to long-range transport, the boundary layer meteorology and lifetime of CH4 in the atmosphere. (C) 2017 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{kavitha17a,
author = {Kavitha, M. and Nair, Prabha R.},
title = {SCIAMACHY observed changes in the column mixing ratio of methane over the Indian region and a comparison with global scenario},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2017},
volume = {166},
pages = {454--466},
doi = {10.1016/j.atmosenv.2017.07.044}
}
|
| Keeling R and Manning A (2014), "5.15 - Studies of Recent Changes in Atmospheric O2\ Content", In Treatise on Geochemistry (Second Edition). , pp. 385-404. Elsevier. |
| Abstract: Abstract A very close coupling exists between changes in atmospheric O2\ and CO2\ concentrations, owing to the chemistry of photosynthesis, respiration, and combustion. The coupling is not perfect, however, because CO2\ variations are partially buffered by reactions involving the inorganic carbon system in seawater, which has no effect on O2. Measurements over the past two decades document variations in O2\ on a range of space and time scales, including a long-term decrease driven mostly by fossil fuel burning and seasonal cycles driven by exchanges with the land biosphere and the oceans. In this chapter, these and other features seen in the measurements are described, also discussing variations in the tracer `atmospheric potential oxygen,' which is a linear combination of O2\ and CO2\ designed to be insensitive to exchanges from the land biosphere and thereby sensitive mostly to oceanic processes. Challenges associated with measuring variations in O2\ are addressed, and various applications of the observations are discussed, including quantifying the magnitude of the global land and ocean carbon sinks and testing ocean biogeochemical models. An updated budget for global carbon sinks based on O2\ measurements from the Scripps O2\ program is presented for the decades of the 1990s and 2000s. |
BibTeX:
@incollection{keeling14a,
author = {R.F. Keeling and A.C. Manning},
editor = {Holland, Heinrich D. and Turekian, Karl K.},
title = {5.15 - Studies of Recent Changes in Atmospheric O2\ Content},
booktitle = {Treatise on Geochemistry (Second Edition)},
publisher = {Elsevier},
year = {2014},
pages = {385--404},
url = {https://www.sciencedirect.com/science/article/pii/B9780080959757004204},
doi = {10.1016/B978-0-08-095975-7.00420-4}
}
|
| Keppel-Aleks G, Wennberg PO and Schneider T ({2011}), "Sources of variations in total column carbon dioxide", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({8}), pp. 3581-3593. |
| Abstract: Observations of gradients in the total CO(2) column, < CO(2)>, are expected to provide improved constraints on surface fluxes of CO(2). Here we use a general circulation model with a variety of prescribed carbon fluxes to investigate how variations in < CO(2)> arise. On diurnal scales, variations are small and are forced by both local fluxes and advection. On seasonal scales, gradients are set by the north-south flux distribution. On synoptic scales, variations arise due to large-scale eddy-driven disturbances of the meridional gradient. In this case, because variations in < CO(2)> are tied to synoptic activity, significant correlations exist between < CO(2)> and dynamical tracers. We illustrate how such correlations can be used to describe the north-south gradients of < CO(2)> and the underlying fluxes on continental scales. These simulations suggest a novel analysis framework for using column observations in carbon cycle science. |
BibTeX:
@article{keppel-aleks11a,
author = {Keppel-Aleks, G. and Wennberg, P. O. and Schneider, T.},
title = {Sources of variations in total column carbon dioxide},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2011},
volume = {11},
number = {8},
pages = {3581--3593},
doi = {10.5194/acp-11-3581-2011}
}
|
| Keppel-Aleks G, Wennberg PO, Washenfelder RA, Wunch D, Schneider T, Toon GC, Andres RJ, Blavier JF, Connor B, Davis KJ, Desai AR, Messerschmidt J, Notholt J, Roehl CM, Sherlock V, Stephens BB, Vay SA and Wofsy SC ({2012}), "The imprint of surface fluxes and transport on variations in total column carbon dioxide", BIOGEOSCIENCES. Vol. {9}({3}), pp. 875-891. |
| Abstract: New observations of the vertically integrated CO2 mixing ratio, aYCO(2)aY (c), from ground-based remote sensing show that variations in CO(2)aY (c) are primarily determined by large-scale flux patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large-scale and local fluxes. Observations of both aYCO(2)aY (c) and CO2 concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in aYCO(2)aY (c) in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface fluxes on atmospheric CO2, these synoptic-scale variations provide useful information that can be used to reveal the meridional flux distribution. We estimate the meridional gradient in aYCO(2)aY (c) from covariations in aYCO(2)aY (c) and potential temperature, theta, a dynamical tracer, on synoptic timescales to evaluate surface flux estimates commonly used in carbon cycle models. We find that simulations using Carnegie Ames Stanford Approach (CASA) biospheric fluxes underestimate both the aYCO(2)aY (c) seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes and the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal fluxes better fit the observations. Our simulations suggest that climatological mean CASA fluxes underestimate boreal growing season NEE (between 45-65A degrees N) by ˜40%. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink. |
BibTeX:
@article{keppel-aleks12a,
author = {Keppel-Aleks, G. and Wennberg, P. O. and Washenfelder, R. A. and Wunch, D. and Schneider, T. and Toon, G. C. and Andres, R. J. and Blavier, J. -F. and Connor, B. and Davis, K. J. and Desai, A. R. and Messerschmidt, J. and Notholt, J. and Roehl, C. M. and Sherlock, V. and Stephens, B. B. and Vay, S. A. and Wofsy, S. C.},
title = {The imprint of surface fluxes and transport on variations in total column carbon dioxide},
journal = {BIOGEOSCIENCES},
year = {2012},
volume = {9},
number = {3},
pages = {875--891},
doi = {10.5194/bg-9-875-2012}
}
|
| Keppel-Aleks G, Wennberg PO, O'Dell CW and Wunch D ({2013}), "Towards constraints on fossil fuel emissions from total column carbon dioxide", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({8}), pp. 4349-4357. |
| Abstract: We assess the large-scale, top-down constraints on regional fossil fuel emissions provided by observations of atmospheric total column CO2, X-CO2. Using an atmospheric general circulation model (GCM) with underlying fossil emissions, we determine the influence of regional fossil fuel emissions on global X-CO2 fields. We quantify the regional contrasts between source and upwind regions and probe the sensitivity of atmospheric X-CO2 to changes in fossil fuel emissions. Regional fossil fuel X-CO2 contrasts can exceed 0.7 ppm based on 2007 emission estimates, but have large seasonal variations due to biospheric fluxes. Contamination by clouds reduces the discernible fossil signatures. Nevertheless, our simulations show that atmospheric fossil X-CO2 can be tied to its source region and that changes in the regional XCO2 contrasts scale linearly with emissions. We test the GCM results against X-CO2 data from the GOSAT satellite. Regional X-CO2 contrasts in GOSAT data generally scale with the predictions from the GCM, but the comparison is limited by the moderate precision of and relatively few observations from the satellite. We discuss how this approach may be useful as a policy tool to verify national fossil emissions, as it provides an independent, observational constraint. |
BibTeX:
@article{keppel-aleks13a,
author = {Keppel-Aleks, G. and Wennberg, P. O. and O'Dell, C. W. and Wunch, D.},
title = {Towards constraints on fossil fuel emissions from total column carbon dioxide},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {8},
pages = {4349--4357},
doi = {10.5194/acp-13-4349-2013}
}
|
| Kim MG (2011), "Errors in mixed layer heights over North America: a multi-model comparison". Thesis at: University of Waterloo. |
BibTeX:
@mastersthesis{kim11a,
author = {Kim, Myung Gwang},
title = {Errors in mixed layer heights over North America: a multi-model comparison},
school = {University of Waterloo},
year = {2011},
url = {https://uwspace.uwaterloo.ca/handle/10012/5968}
}
|
| Kim J, Kim HM and Cho C-H (2012), "Application of Carbon Tracking System based on ensemble Kalman Filter on the diagnosis of Carbon Cycle in Asia", Atmosphere. Vol. 22(4), pp. 415-427. |
BibTeX:
@article{kim12a,
author = {Kim, JinWoong and Kim, Hyun Mee and Cho, Chun-Ho},
title = {Application of Carbon Tracking System based on ensemble Kalman Filter on the diagnosis of Carbon Cycle in Asia},
journal = {Atmosphere},
year = {2012},
volume = {22},
number = {4},
pages = {415--427},
url = {http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=KSHHDL_2012_v22n4_415}
}
|
| Kim J, Kim HM and Cho C-H ({2014}), "The effect of optimization and the nesting domain on carbon flux analyses in Asia using a carbon tracking system based on the ensemble Kalman filter", ASIA-PACIFIC JOURNAL OF ATMOSPHERIC SCIENCES., MAY, {2014}. Vol. {50}({3}), pp. 327-344. |
| Abstract: To estimate the surface carbon flux in Asia and investigate the effect of the nesting domain on carbon flux analyses in Asia, two experiments with different nesting domains were conducted using the CarbonTracker developed by the National Oceanic and Atmospheric Administration. CarbonTracker is an inverse modeling system that uses an ensemble Kalman filter (EnKF) to estimate surface carbon fluxes from surface CO2 observations. One experiment was conducted with a nesting domain centered in Asia and the other with a nesting domain centered in North America. Both experiments analyzed the surface carbon fluxes in Asia from 2001 to 2006. The results showed that prior surface carbon fluxes were underestimated in Asia compared with the optimized fluxes. The optimized biosphere fluxes of the two experiments exhibited roughly similar spatial patterns but different magnitudes. Weekly cumulative optimized fluxes showed more diverse patterns than the prior fluxes, indicating that more detailed flux analyses were conducted during the optimization. The nesting domain in Asia produced a detailed estimate of the surface carbon fluxes in Asia and exhibited better agreement with the CO2 observations. Finally, the simulated background atmospheric CO2 concentrations in the experiment with the nesting domain in Asia were more consistent with the observed CO2 concentrations than those in the experiment with the nesting domain in North America. The results of this study suggest that surface carbon fluxes in Asia can be estimated more accurately using an EnKF when the nesting domain is centered in Asian regions. |
BibTeX:
@article{kim14a,
author = {Kim, Jinwoong and Kim, Hyun Mee and Cho, Chun-Ho},
title = {The effect of optimization and the nesting domain on carbon flux analyses in Asia using a carbon tracking system based on the ensemble Kalman filter},
journal = {ASIA-PACIFIC JOURNAL OF ATMOSPHERIC SCIENCES},
year = {2014},
volume = {50},
number = {3},
pages = {327--344},
doi = {10.1007/s13143-014-0020-y}
}
|
| Kim J, Kim HM and Cho CH ({2014}), "Influence of CO2 observations on the optimized CO2 flux in an ensemble Kalman filter", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({24}), pp. 13515-13530. |
| Abstract: In this study, the effect of CO2 observations on an analysis of surface CO2 flux was calculated using an influence matrix in the CarbonTracker, which is an inverse modeling system for estimating surface CO2 flux based on an ensemble Kalman filter. The influence matrix represents a sensitivity of the analysis to observations. The experimental period was from January 2000 to December 2009. The diagonal element of the influence matrix (i.e., analysis sensitivity) is globally 4.8% on average, which implies that the analysis extracts 4.8% of the information from the observations and 95.2% from the background each assimilation cycle. Because the surface CO2 flux in each week is optimized by 5 weeks of observations, the cumulative impact over 5 weeks is 19.1 much greater than 4.8 %. The analysis sensitivity is inversely proportional to the number of observations used in the assimilation, which is distinctly apparent in continuous observation categories with a sufficient number of observations. The time series of the globally averaged analysis sensitivities shows seasonal variations, with greater sensitivities in summer and lower sensitivities in winter, which is attributed to the surface CO2 flux uncertainty. The time-averaged analysis sensitivities in the Northern Hemisphere are greater than those in the tropics and the Southern Hemisphere. The trace of the influence matrix (i.e., information content) is a measure of the total information extracted from the observations. The information content indicates an imbalance between the observation coverage in North America and that in other regions. Approximately half of the total observational information is provided by continuous observations, mainly from North America, which indicates that continuous observations are the most informative and that comprehensive coverage of additional observations in other regions is necessary to estimate the surface CO2 flux in these areas as accurately as in North America. |
BibTeX:
@article{kim14b,
author = {Kim, J. and Kim, H. M. and Cho, C. -H.},
title = {Influence of CO2 observations on the optimized CO2 flux in an ensemble Kalman filter},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2014},
volume = {14},
number = {24},
pages = {13515--13530},
doi = {10.5194/acp-14-13515-2014}
}
|
| Kim H, Kim HM, Kim J and Cho C-H (2016), "A Comparison of the Atmospheric CO2 Concentrations Obtained by an Inverse Modeling System and Passenger Aircraft Based Measurement", Atmosphere. Vol. 26(3), pp. 387-400. |
BibTeX:
@article{kim16a,
author = {Hyunjung Kim and Hyun Mee Kim and Jinwoong Kim and Chun-Ho Cho},
title = {A Comparison of the Atmospheric CO2 Concentrations Obtained by an Inverse Modeling System and Passenger Aircraft Based Measurement},
journal = {Atmosphere},
year = {2016},
volume = {26},
number = {3},
pages = {387--400},
url = {http://www.j-komes.or.kr/xml/07935/07935.pdf}
}
|
| Kim J, Kim HM, Cho C-H, Boo K-O, Jacobson AR, Sasakawa M, Machida T, Arshinov M and Fedoseev N ({2017}), "Impact of Siberian observations on the optimization of surface CO2 flux", ATMOSPHERIC CHEMISTRY AND PHYSICS., FEB 24, {2017}. Vol. {17}({4}), pp. 2881-2899. |
| Abstract: To investigate the effect of additional CO2 observations in the Siberia region on the Asian and global surface CO2 flux analyses, two experiments using different observation data sets were performed for 2000-2009. One experiment was conducted using a data set that includes additional observations of Siberian tower measurements (Japan-Russia Siberian Tall Tower Inland Observation Network: JR-STATION), and the other experiment was conducted using a data set without the above additional observations. The results show that the global balance of the sources and sinks of surface CO2 fluxes was maintained for both experiments with and without the additional observations. While the magnitude of the optimized surface CO2 flux uptake and flux uncertainty in Siberia decreased from 1.17 +/- 0.93 to 0.77 +/- 0.70 PgC yr(-1), the magnitude of the optimized surface CO2 flux uptake in the other regions (e.g., Europe) of the Northern Hemisphere (NH) land increased for the experiment with the additional observations, which affect the longitudinal distribution of the total NH sinks. This change was mostly caused by changes in the magnitudes of surface CO2 flux in June and July. The observation impact measured by uncertainty reduction and self-sensitivity tests shows that additional observations provide useful information on the estimated surface CO2 flux. The average uncertainty reduction of the conifer forest of Eurasian boreal (EB) is 29.1% and the average self-sensitivities at the JR-STATION sites are approximately 60% larger than those at the towers in North America. It is expected that the Siberian observations play an important role in estimating surface CO2 flux in the NH land (e.g., Siberia and Europe) in the future. |
BibTeX:
@article{kim17a,
author = {Kim, Jinwoong and Kim, Hyun Mee and Cho, Chun-Ho and Boo, Kyung-On and Jacobson, Andrew R. and Sasakawa, Motoki and Machida, Toshinobu and Arshinov, Mikhail and Fedoseev, Nikolay},
title = {Impact of Siberian observations on the optimization of surface CO2 flux},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {4},
pages = {2881--2899},
doi = {10.5194/acp-17-2881-2017}
}
|
| Kim H, Kim HM, Kim J and Cho C-H (2017), "Effect of data assimilation parameters on the optimized surface CO2 flux in Asia", Asia-Pacific Journal of Atmospheric Sciences., September, 2017. , pp. 1-17. |
| Abstract: In this study, CarbonTracker, an inverse modeling system based on the ensemble Kalman filter, was used to evaluate the effects of data assimilation parameters (assimilation window length and ensemble size) on the estimation of surface CO2 fluxes in Asia. Several experiments with different parameters were conducted, and the results were verified using CO2 concentration observations. The assimilation window lengths tested were 3, 5, 7, and 10 weeks, and the ensemble sizes were 100, 150, and 300. Therefore, a total of 12 experiments using combinations of these parameters were conducted. The experimental period was from January 2006 to December 2009. Differences between the optimized surface CO2 fluxes of the experiments were largest in the Eurasian Boreal (EB) area, followed by Eurasian Temperate (ET) and Tropical Asia (TA), and were larger in boreal summer than in boreal winter. The effect of ensemble size on the optimized biosphere flux is larger than the effect of the assimilation window length in Asia, but the importance of them varies in specific regions in Asia. The optimized biosphere flux was more sensitive to the assimilation window length in EB, whereas it was sensitive to the ensemble size as well as the assimilation window length in ET. The larger the ensemble size and the shorter the assimilation window length, the larger the uncertainty (i.e., spread of ensemble) of optimized surface CO2 fluxes. The 10-week assimilation window and 300 ensemble size were the optimal configuration for CarbonTracker in the Asian region based on several verifications using CO2 concentration measurements. |
BibTeX:
@article{kim17b,
author = {Kim, Hyunjung and Kim, Hyun Mee and Kim, Jinwoong and Cho, Chun-Ho},
title = {Effect of data assimilation parameters on the optimized surface CO2 flux in Asia},
journal = {Asia-Pacific Journal of Atmospheric Sciences},
year = {2017},
pages = {1--17},
doi = {10.1007/s13143-017-0049-9}
}
|
| Kim H, Kim HM, Cho M, Park J and Kim D-H ({2018}), "Development of the Aircraft CO2 Measurement Data Assimilation System to Improve the Estimation of Surface CO2 Fluxes Using an Inverse Modeling System", ATMOSPHERE-KOREA., JUN, {2018}. Vol. {28}({2}), pp. {113-121}. |
| Abstract: In order to monitor greenhouse gases including CO2, various types of surface-, aircraft-, and satellite-based measurement projects have been conducted. These data help understand the variations of greenhouse gases and are used in atmospheric inverse modeling systems to simulate surface fluxes for greenhouse gases. CarbonTracker is a system for estimating surface CO2 flux, using an atmospheric inverse modeling method, based on only surface observation data. Because of the insufficient surface observation data available for accurate estimation of the surface CO2 flux, additional observations would be required. In this study, a system that assimilates aircraft CO2 measurement data in CarbonTracker (CT2013B) is developed, and the estimated results from this data assimilation system are evaluated. The aircraft CO2 measurement data used are obtained from the Comprehensive Observation Network for Trace gases by the Airliner (CONTRAIL) project. The developed system includes the preprocessor of the raw observation data, the observation operator, and the ensemble Kalman filter (EnKF) data assimilation process. After preprocessing the raw data, the modeled value corresponding spatially and temporally to each observation is calculated using the observation operator. These modeled values and observations are then averaged in space and time, and used in the EnKF data assimilation process. The modeled values are much closer to the observations and show smaller biases and root-mean-square errors, after the assimilation of the aircraft CO2 measurement data. This system could also be used to assimilate other aircraft CO2 measurement data in CarbonTracker. |
BibTeX:
@article{kim18a,
author = {Kim, Hyunjung and Kim, Hyun Mee and Cho, Minkwang and Park, Jun and Kim, Dae-Hui},
title = {Development of the Aircraft CO2 Measurement Data Assimilation System to Improve the Estimation of Surface CO2 Fluxes Using an Inverse Modeling System},
journal = {ATMOSPHERE-KOREA},
year = {2018},
volume = {28},
number = {2},
pages = {113-121},
doi = {{10.14191/Atmos.2018.28.2.113}}
}
|
| King AW, Andres RJ, Davis KJ, Hafer M, Hayes DJ, Huntzinger DN, de Jong B, Kurz WA, McGuire AD, Vargas R, Wei Y, West TO and Woodall CW ({2015}), "North America's net terrestrial CO2 exchange with the atmosphere 1990-2009", BIOGEOSCIENCES. Vol. {12}({2}), pp. 399-414. |
| Abstract: Scientific understanding of the global carbon cycle is required for developing national and international policy to mitigate fossil fuel CO2 emissions by managing terrestrial carbon uptake. Toward that understanding and as a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP) project, this paper provides a synthesis of net land-atmosphere CO2 exchange for North America (Canada, United States, and Mexico) over the period 1990-2009. Only CO2 is considered, not methane or other greenhouse gases. This synthesis is based on results from three different methods: atmospheric inversion, inventory-based methods and terrestrial biosphere modeling. All methods indicate that the North American land surface was a sink for atmospheric CO2, with a net transfer from atmosphere to land. Estimates ranged from -890 to -280 TgC yr(-1), where the mean of atmospheric inversion estimates forms the lower bound of that range (a larger land sink) and the inventory-based estimate using the production approach the upper (a smaller land sink). This relatively large range is due in part to differences in how the approaches represent trade, fire and other disturbances and which ecosystems they include. Integrating across estimates, ``best'' estimates (i.e., measures of central tendency) are -472 +/- 281 TgC yr(-1) based on the mean and standard deviation of the distribution and -360 TgC yr(-1) (with an interquartile range of -496 to -337) based on the median. Considering both the fossil fuel emissions source and the land sink, our analysis shows that North America was, however, a net contributor to the growth of CO2 in the atmosphere in the late 20th and early 21st century. With North America's mean annual fossil fuel CO2 emissions for the period 1990-2009 equal to 1720 Tg C yr(-1) and assuming the estimate of -472 TgC yr(-1) as an approximation of the true terrestrial CO2 sink, the continent's source : sink ratio for this time period was 1720 : 472, or nearly 4 : 1. |
BibTeX:
@article{king15a,
author = {King, A. W. and Andres, R. J. and Davis, K. J. and Hafer, M. and Hayes, D. J. and Huntzinger, D. N. and de Jong, B. and Kurz, W. A. and McGuire, A. D. and Vargas, R. and Wei, Y. and West, T. O. and Woodall, C. W.},
title = {North America's net terrestrial CO2 exchange with the atmosphere 1990-2009},
journal = {BIOGEOSCIENCES},
year = {2015},
volume = {12},
number = {2},
pages = {399--414},
doi = {10.5194/bg-12-399-2015}
}
|
| Kivi R and Heikkinen P ({2016}), "Fourier transform spectrometer measurements of column CO2 at Sodankyla, Finland", GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS. Vol. {5}({2}), pp. 271-279. |
| Abstract: Fourier transform spectrometer (FTS) observations at Sodankyla, Finland (67.4 degrees N, 26.6 degrees E) have been performed since early 2009. The FTS instrument is participating in the Total Carbon Column Observing Network (TCCON) and has been optimized to measure abundances of the key greenhouse gases in the atmosphere. Sodankyla is the only TCCON station in the Fennoscandia region. Here we report the measured CO2 time series over a 7-year period (2009-2015) and provide a description of the FTS system and data processing at Sodankyla. We find the lowest monthly column CO2 values in August and the highest monthly values during the February-May season. Inter-annual variability is the highest in the June-September period, which correlates with the growing season. During the time period of FTS measurements from 2009 to 2015, we have observed a 2.2 +/- 0.2 ppm increase per year in column CO2. The monthly mean column CO2 values have exceeded 400 ppm level for the first time in February 2014. |
BibTeX:
@article{kivi16a,
author = {Kivi, Rigel and Heikkinen, Pauli},
title = {Fourier transform spectrometer measurements of column CO2 at Sodankyla, Finland},
journal = {GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS},
year = {2016},
volume = {5},
number = {2},
pages = {271--279},
doi = {10.5194/gi-5-271-2016}
}
|
| Klappenbach F, Bertleff M, Kostinek J, Hase F, Blumenstock T, Agusti-Panareda A, Razinger M and Butz A ({2015}), "Accurate mobile remote sensing of XCO2 and XCH4 latitudinal transects from aboard a research vessel", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({12}), pp. 5023-5038. |
| Abstract: A portable Fourier transform spectrometer (FTS), model EM27/SUN, was deployed onboard the research vessel Polarstern to measure the column-average dry air mole fractions of carbon dioxide (XCO2) and methane (XCH4) by means of direct sunlight absorption spectrometry. We report on technical developments as well as data calibration and reduction measures required to achieve the targeted accuracy of fractions of a percent in retrieved XCO2 and XCH4 while operating the instrument under field conditions onboard the moving platform during a 6-week cruise on the Atlantic from Cape Town (South Africa, 34 degrees S, 18 degrees E; 5 March 2014) to Bremerhaven (Germany, 54 degrees N, 19 degrees E; 14 April 2014). We demonstrate that our solar tracker typically achieved a tracking precision of better than 0.05 degrees toward the center of the sun throughout the ship cruise which facilitates accurate XCO2 and XCH4 retrievals even under harsh ambient wind conditions. We define several quality filters that screen spectra, e.g., when the field of view was partially obstructed by ship structures or when the lines-of-sight crossed the ship exhaust plume. The measurements in clean oceanic air, can be used to characterize a spurious air-mass dependency. After the campaign, deployment of the spectrometer alongside the TCCON (Total Carbon Column Observing Network) instrument at Karlsruhe, Germany, allowed for determining a calibration factor that makes the entire campaign record traceable to World Meteorological Organization (WMO) standards. Comparisons to observations of the GOSAT satellite and concentration fields modeled by the European Centre for Medium-Range Weather Forecasts (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) demonstrate that the observational setup is well suited to provide validation opportunities above the ocean and along interhemispheric transects. |
BibTeX:
@article{klappenbach15a,
author = {Klappenbach, F. and Bertleff, M. and Kostinek, J. and Hase, F. and Blumenstock, T. and Agusti-Panareda, A. and Razinger, M. and Butz, A.},
title = {Accurate mobile remote sensing of XCO2 and XCH4 latitudinal transects from aboard a research vessel},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2015},
volume = {8},
number = {12},
pages = {5023--5038},
doi = {10.5194/amt-8-5023-2015}
}
|
| Klappenbach FW (2016), "Mobile spectroscopic measurements of atmospheric carbon dioxide and methane". Thesis at: Karlsruher Instituts für Technologie. |
BibTeX:
@phdthesis{klappenbach16a,
author = {Klappenbach, Friedrich Wilhelm},
title = {Mobile spectroscopic measurements of atmospheric carbon dioxide and methane},
school = {Karlsruher Instituts für Technologie},
year = {2016},
url = {https://d-nb.info/1114312576/34}
}
|
| Koffi EN, Rayner PJ, Scholze M, Chevallier F and Kaminski T ({2013}), "Quantifying the constraint of biospheric process parameters by CO2 concentration and flux measurement networks through a carbon cycle data assimilation system", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({21}), pp. 10555-10572. |
| Abstract: The sensitivity of the process parameters of the Biosphere Energy Transfer HYdrology (BETHY) model to choices of atmospheric concentration network, high frequency terrestrial fluxes, and the choice of flux measurement network is investigated by using a carbon cycle data assimilation system. We use BETHY-generated fluxes as a proxy of flux measurements. Results show that monthly mean or low-frequency observations of CO2 concentration provide strong constraints on parameters relevant for net flux (NEP) but only weak constraints for parameters controlling gross fluxes. The use of high-frequency CO2 concentration observations, which has led to great refinement of spatial scales in inversions of net flux, adds little to the observing system in the Carbon Cycle Data Assimilation System (CCDAS) case. This unexpected result is explained by the fact that the stations of the CO2 concentration network we use are not well placed to measure such high frequency signals. Indeed, CO2 concentration sensitivities relevant for such high frequency fluxes are found to be largely confined in the vicinity of the corresponding fluxes, and are therefore not well observed by background monitoring stations. In contrast, our results clearly show the potential of flux measurements to better constrain the model parameters relevant for gross primary productivity (GPP) and net primary productivity (NPP). Given uncertainties in the spatial description of ecosystem functions, we recommend a combined observing strategy. |
BibTeX:
@article{koffi13a,
author = {Koffi, E. N. and Rayner, P. J. and Scholze, M. and Chevallier, F. and Kaminski, T.},
title = {Quantifying the constraint of biospheric process parameters by CO2 concentration and flux measurement networks through a carbon cycle data assimilation system},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {21},
pages = {10555--10572},
doi = {10.5194/acp-13-10555-2013}
}
|
| Kondo M, Ichii K, Takagi H and Sasakawa M ({2015}), "Comparison of the data-driven top-down and bottom-up global terrestrial CO2 exchanges: GOSAT CO2 inversion and empirical eddy flux upscaling", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., JUL, {2015}. Vol. {120}({7}), pp. 1226-1245. |
| Abstract: We examined the consistency between terrestrial biosphere fluxes (terrestrial CO2 exchanges) from data-driven top-down (GOSAT CO2 inversion) and bottom-up (empirical eddy flux upscaling based on a support vector regression (SVR) model) approaches over 42 global terrestrial regions from June 2009 to October 2011. Seasonal variations of the biosphere fluxes by the two approaches agreed well in boreal and temperate regions across the Northern Hemisphere. Both fluxes also exhibited strong anomalous signals in response to contrasting anomalous spring temperatures observed in North America and boreal Eurasia. This indicates that the CO2 concentration data integrated in the GOSAT inversion and the meteorological and vegetation data in the SVR models are equally effective in producing spatiotemporal variations of biosphere flux. Meanwhile, large differences in seasonality were found in subtropical and tropical South America, South Asia, and Africa. The GOSAT inversion showed seasonal variations that pivoted around CO2 neutral, while the SVR model showed seasonal variations that tended toward CO2 sink. Thus, a large difference in CO2 budget was identified between the two approaches in subtropical and tropical regions across the Southern Hemisphere. Examination of the integrated data revealed that the large tropical sink of CO2 by the SVR model was an artifact due to the underrepresented biosphere fluxes predicted by limited eddy flux data for tropical biomes. Because of the global coverage of CO2 concentration data, the GOSAT inversion provides better estimates of continental CO2 flux than the SVR model in the Southern Hemisphere. |
BibTeX:
@article{kondo15a,
author = {Kondo, Masayuki and Ichii, Kazuhito and Takagi, Hiroshi and Sasakawa, Motoki},
title = {Comparison of the data-driven top-down and bottom-up global terrestrial CO2 exchanges: GOSAT CO2 inversion and empirical eddy flux upscaling},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2015},
volume = {120},
number = {7},
pages = {1226--1245},
doi = {10.1002/2014JG002866}
}
|
| Konopka P, Ploeger F, Tao M and Riese M ({2017}), "Regionally Resolved Diagnostic of Transport: A Simplified Forward Model for CO2", JOURNAL OF THE ATMOSPHERIC SCIENCES., AUG, {2017}. Vol. {74}({8}), pp. 2689-2700. |
| Abstract: Simply diagnostic tools are useful for understanding transport processes in complex chemistry transport models (CTMs). For this purpose, a combined use of the airmass origin fractions (AOFs) and regionally resolved mean ages (RMAs) is presented. This approach merges the concept of the origin of air with the well-known theory of the mean age of air (AoA) for different regions covering the whole Earth. The authors show how the AoA calculated relative to Earth's surface can be decomposed into regionally resolved components (i.e., into RMAs). Using both AOFs and RMAs, the authors discuss differences in the seasonality of transport from the Northern and Southern Hemispheres into the tropical tropopause layer (TTL), the asymmetries of the interhemispheric exchange, and differences in relation to the continental or oceanic origin of air. Furthermore, a simplified transport model for a chemically passive species (tracer) is formulated that has some potential to approximate the full transport within a CTM. This analytic approach uses the AOFs as well as the RMAs as parameters to propagate a tracer prescribed on Earth's surface (lower boundary condition). This method is exactly valid for sources that change linearly with time in each of the considered regions. The authors analyze how well this approach approximates the propagation of CO2 from the planetary boundary layer (PBL) into the whole atmosphere. The CO2 values in the PBL are specified by the CarbonTracker dataset. The authors discuss how this approach can be used for inverse modeling of CO2. |
BibTeX:
@article{konopka17a,
author = {Konopka, Paul and Ploeger, Felix and Tao, Mengchu and Riese, Martin},
title = {Regionally Resolved Diagnostic of Transport: A Simplified Forward Model for CO2},
journal = {JOURNAL OF THE ATMOSPHERIC SCIENCES},
year = {2017},
volume = {74},
number = {8},
pages = {2689--2700},
doi = {10.1175/JAS-D-16-0367.1}
}
|
| Xing-Xia K, Zhang M-G and Peng Z (2013), "Numerical Simulation of CO2 Concentrations in East Asia with RAMS-CMAQ", Atmospheric and Oceanic Science Letters. Vol. 6(4), pp. 179-184.
[BibTeX] |
BibTeX:
@article{kou13a,
author = {Kou Xing-Xia and Zhang, Mei-Gen and Peng, Zhen},
title = {Numerical Simulation of CO2 Concentrations in East Asia with RAMS-CMAQ},
journal = {Atmospheric and Oceanic Science Letters},
year = {2013},
volume = {6},
number = {4},
pages = {179--184}
}
|
| Kou X, Zhang M, Peng Z and Wang Y ({2015}), "Assessment of the biospheric contribution to surface atmospheric CO2 concentrations over East Asia with a regional chemical transport model", ADVANCES IN ATMOSPHERIC SCIENCES., MAR, {2015}. Vol. {32}({3}), pp. 287-300. |
| Abstract: A regional chemical transport model, RAMS-CMAQ, was employed to assess the impacts of biosphere-atmosphere C-2 exchange on seasonal variations in atmospheric C-2 concentrations over East Asia. Simulated C-2 concentrations were compared with observations at 12 surface stations and the comparison showed they were generally in good agreement. Both observations and simulations suggested that surface C-2 over East Asia features a summertime trough due to biospheric absorption, while in some urban areas surface C-2 has a distinct summer peak, which could be attributed to the strong impact from anthropogenic emissions. Analysis of the model results indicated that biospheric fluxes and fossil-fuel emissions are comparably important in shaping spatial distributions of C-2 near the surface over East Asia. Biospheric flux plays an important role in the prevailing spatial pattern of C-2 enhancement and reduction on the synoptic scale due to the strong seasonality of biospheric C-2 flux. The elevation of C-2 levels by the biosphere during winter was found to be larger than 5 ppm in North China and Southeast China, and during summertime a significant depletion (a (c) 3/4 7 ppm) occurred in most areas, except for the Indo-China Peninsula where positive bioflux values were found. |
BibTeX:
@article{kou15a,
author = {Kou, Xingxia and Zhang, Meigen and Peng, Zhen and Wang, Yinghong},
title = {Assessment of the biospheric contribution to surface atmospheric CO2 concentrations over East Asia with a regional chemical transport model},
journal = {ADVANCES IN ATMOSPHERIC SCIENCES},
year = {2015},
volume = {32},
number = {3},
pages = {287--300},
doi = {10.1007/s00376-014-4059-6}
}
|
| Kou X, Tian X, Zhang M, Peng Z and Zhang X ({2017}), "Accounting for CO2 Variability over East Asia with a Regional Joint Inversion System and Its Preliminary Evaluation", JOURNAL OF METEOROLOGICAL RESEARCH., OCT, {2017}. Vol. {31}({5}), pp. 834-851. |
| Abstract: A regional surface carbon dioxide (CO2) flux inversion system, the Tan-Tracker-Region, was developed by incorporating an assimilation scheme into the Community Multiscale Air Quality (CMAQ) regional chemical transport model to resolve fine-scale CO2 variability over East Asia. The proper orthogonal decomposition-based ensemble four-dimensional variational data assimilation approach (POD-4DVar) is the core algorithm for the joint assimilation framework, and simultaneous assimilations of CO2 concentrations and surface CO2 fluxes are applied to help reduce the uncertainty in initial CO2 concentrations. A persistence dynamical model was developed to describe the evolution of the surface CO2 fluxes and help avoid the ``signal-to-noise'' problem; thus, CO2 fluxes could be estimated as a whole at the model grid scale, with better use of observation information. The performance of the regional inversion system was evaluated through a group of single-observation-based observing system simulation experiments (OSSEs). The results of the experiments suggest that a reliable performance of Tan-Tracker-Region is dependent on certain assimilation parameter choices, for example, an optimized window length of approximately 3 h, an ensemble size of approximately 100, and a covariance localization radius of approximately 320 km. This is probably due to the strong diurnal variation and spatial heterogeneity in the fine-scale CMAQ simulation, which could affect the performance of the regional inversion system. In addition, because all observations can be artificially obtained in OSSEs, the performance of Tan-Tracker-Region was further evaluated through different densities of the artificial observation network in different CO2 flux situations. The results indicate that more observation sites would be useful to systematically improve the estimation of CO2 concentration and flux in large areas over the model domain. The work presented here forms a foundation for future research in which a thorough estimation of CO2 flux variability over East Asia could be performed with the regional inversion system. |
BibTeX:
@article{kou17a,
author = {Kou, Xingxia and Tian, Xiangjun and Zhang, Meigen and Peng, Zhen and Zhang, Xiaoling},
title = {Accounting for CO2 Variability over East Asia with a Regional Joint Inversion System and Its Preliminary Evaluation},
journal = {JOURNAL OF METEOROLOGICAL RESEARCH},
year = {2017},
volume = {31},
number = {5},
pages = {834--851},
doi = {10.1007/s13351-017-6149-8}
}
|
| Kountouris P, Gerbig C, Totsche KU, Dolman AJ, Meesters AGCA, Broquet G, Maignan F, Gioli B, Montagnani L and Helfter C ({2015}), "An objective prior error quantification for regional atmospheric inverse applications", BIOGEOSCIENCES. Vol. {12}({24}), pp. 7403-7421. |
| Abstract: Assigning proper prior uncertainties for inverse modelling of CO2 is of high importance, both to regularise the otherwise ill-constrained inverse problem and to quantitatively characterise the magnitude and structure of the error between prior and `true' flux. We use surface fluxes derived from three biosphere models - VPRM, ORCHIDEE, and 5PM - and compare them against daily averaged fluxes from 53 eddy covariance sites across Europe for the year 2007 and against repeated aircraft flux measurements encompassing spatial transects. In addition we create synthetic observations using modelled fluxes instead of the observed ones to explore the potential to infer prior uncertainties from model-model residuals. To ensure the realism of the synthetic data analysis, a random measurement noise was added to the modelled tower fluxes which were used as reference. The temporal autocorrelation time for tower model-data residuals was found to be around 30 days for both VPRM and ORCHIDEE but significantly different for the 5PM model with 70 days. This difference is caused by a few sites with large biases between the data and the 5PM model. The spatial correlation of the model-data residuals for all models was found to be very short, up to few tens of kilometres but with uncertainties up to 100 % of this estimation. Propagating this error structure to annual continental scale yields an uncertainty of 0.06 Gt C and strongly underestimates uncertainties typically used from atmospheric inversion systems, revealing another potential source of errors. Long spatial e-folding correlation lengths up to several hundreds of kilometres were determined when synthetic data were used. Results from repeated aircraft transects in south-western France are consistent with those obtained from the tower sites in terms of spatial autocorrelation (35 km on average) while temporal autocorrelation is markedly lower (13 days). Our findings suggest that the different prior models have a common temporal error structure. Separating the analysis of the statistics for the model data residuals by seasons did not result in any significant differences of the spatial e-folding correlation lengths. |
BibTeX:
@article{kountouris15a,
author = {Kountouris, P. and Gerbig, C. and Totsche, K. -U. and Dolman, A. J. and Meesters, A. G. C. A. and Broquet, G. and Maignan, F. and Gioli, B. and Montagnani, L. and Helfter, C.},
title = {An objective prior error quantification for regional atmospheric inverse applications},
journal = {BIOGEOSCIENCES},
year = {2015},
volume = {12},
number = {24},
pages = {7403--7421}
}
|
| Kountouris P, Gerbig C, Rodenbeck C, Karstens U, Koch TF and Heimann M ({2018}), "Technical Note: Atmospheric CO2 inversions on the mesoscale using data-driven prior uncertainties: methodology and system evaluation", ATMOSPHERIC CHEMISTRY AND PHYSICS., MAR 2, {2018}. Vol. {18}({4}), pp. {3027-3045}. |
| Abstract: Atmospheric inversions are widely used in the optimization of surface carbon fluxes on a regional scale using information from atmospheric CO2 dry mole fractions. In many studies the prior flux uncertainty applied to the inversion schemes does not directly reflect the true flux uncertainties but is used to regularize the inverse problem. Here, we aim to implement an inversion scheme using the Jena inversion system and applying a prior flux error structure derived from a model-data residual analysis using high spatial and temporal resolution over a full year period in the European domain. We analyzed the performance of the inversion system with a synthetic experiment, in which the flux constraint is derived following the same residual analysis but applied to the model-model mismatch. The synthetic study showed a quite good agreement between posterior and ``true'' fluxes on European, country, annual and monthly scales. Posterior monthly and country-aggregated fluxes improved their correlation coefficient with the ``known truth'' by 7% compared to the prior estimates when compared to the reference, with a mean correlation of 0.92. The ratio of the SD between the posterior and reference and between the prior and reference was also reduced by 33% with a mean value of 1.15. We identified temporal and spatial scales on which the inversion system maximizes the derived information; monthly temporal scales at around 200 km spatial resolution seem to maximize the information gain. |
BibTeX:
@article{kountouris18a,
author = {Kountouris, Panagiotis and Gerbig, Christoph and Rodenbeck, Christian and Karstens, Ute and Koch, Thomas Frank and Heimann, Martin},
title = {Technical Note: Atmospheric CO2 inversions on the mesoscale using data-driven prior uncertainties: methodology and system evaluation},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2018},
volume = {18},
number = {4},
pages = {3027-3045},
doi = {{10.5194/acp-18-3027-2018}}
}
|
| Koven CD (2016), "Role of CO2, climate and land use in regulating the seasonal amplitude increase of carbon fluxes in terrestrial ecosystems: a multimodel analysis", Biogeosciences. Vol. 13(17), pp. 5121. |
BibTeX:
@article{koven16a,
author = {Koven, Charles D},
title = {Role of CO2, climate and land use in regulating the seasonal amplitude increase of carbon fluxes in terrestrial ecosystems: a multimodel analysis},
journal = {Biogeosciences},
year = {2016},
volume = {13},
number = {17},
pages = {5121},
url = {http://search.proquest.com/openview/6b2e171c3b3e9903f77f7fd2002927a3/1?pq-origsite=gscholar&cbl=105740}
}
|
| Kretschmer R, Gerbig C, Karstens U and Koch FT ({2012}), "Error characterization of CO2 vertical mixing in the atmospheric transport model WRF-VPRM", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({5}), pp. 2441-2458. |
| Abstract: One of the dominant uncertainties in inverse estimates of regional CO2 surface-atmosphere fluxes is related to model errors in vertical transport within the planetary boundary layer (PBL). In this study we present the results from a synthetic experiment using the atmospheric model WRF-VPRM to realistically simulate transport of CO2 for large parts of the European continent at 10 km spatial resolution. To elucidate the impact of vertical mixing error on modeled CO2 mixing ratios we simulated a month during the growing season (August 2006) with different commonly used parameterizations of the PBL (Mellor-Yamada-JanjiA double dagger (MYJ) and Yonsei-University (YSU) scheme). To isolate the effect of transport errors we prescribed the same CO2 surface fluxes for both simulations. Differences in simulated CO2 mixing ratios (model bias) were on the order of 3 ppm during daytime with larger values at night. We present a simple method to reduce this bias by 70-80% when the true height of the mixed layer is known. |
BibTeX:
@article{kretschmer12a,
author = {Kretschmer, R. and Gerbig, C. and Karstens, U. and Koch, F. -T.},
title = {Error characterization of CO2 vertical mixing in the atmospheric transport model WRF-VPRM},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2012},
volume = {12},
number = {5},
pages = {2441--2458},
doi = {10.5194/acp-12-2441-2012}
}
|
| Kulawik SS, Jones DBA, Nassar R, Irion FW, Worden JR, Bowman KW, Machida T, Matsueda H, Sawa Y, Biraud SC, Fischer ML and Jacobson AR ({2010}), "Characterization of Tropospheric Emission Spectrometer (TES) CO2 for carbon cycle science", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({12}), pp. 5601-5623. |
BibTeX:
@article{kulawik10a,
author = {Kulawik, S. S. and Jones, D. B. A. and Nassar, R. and Irion, F. W. and Worden, J. R. and Bowman, K. W. and Machida, T. and Matsueda, H. and Sawa, Y. and Biraud, S. C. and Fischer, M. L. and Jacobson, A. R.},
title = {Characterization of Tropospheric Emission Spectrometer (TES) CO2 for carbon cycle science},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2010},
volume = {10},
number = {12},
pages = {5601--5623},
doi = {10.5194/acp-10-5601-2010}
}
|
| Kulawik SS, Worden JR, Wofsy SC, Biraud SC, Nassar R, Jones DBA, Olsen ET, Jimenez R, Park S, Santoni GW, Daube BC, Pittman JV, Stephens BB, Kort EA, Osterman GB and Team T ({2013}), "Comparison of improved Aura Tropospheric Emission Spectrometer CO2 with HIPPO and SGP aircraft profile measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({6}), pp. 3205-3225. |
BibTeX:
@article{kulawik13a,
author = {Kulawik, S. S. and Worden, J. R. and Wofsy, S. C. and Biraud, S. C. and Nassar, R. and Jones, D. B. A. and Olsen, E. T. and Jimenez, R. and Park, S. and Santoni, G. W. and Daube, B. C. and Pittman, J. V. and Stephens, B. B. and Kort, E. A. and Osterman, G. B. and TES Team},
title = {Comparison of improved Aura Tropospheric Emission Spectrometer CO2 with HIPPO and SGP aircraft profile measurements},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {6},
pages = {3205--3225},
doi = {10.5194/acp-13-3205-2013}
}
|
| Kulawik S, Wunch D, O'Dell C, Frankenberg C, Reuter M, Oda T, Chevallier F, Sherlock V, Buchwitz M, Osterman G, Miller CE, Wennberg PO, Griffith D, Morino I, Dubey MK, Deutscher NM, Notholt J, Hase F, Warneke T, Sussmann R, Robinson J, Strong K, Schneider M, De Maziere M, Shiomi K, Feist DG, Iraci LT and Wolf J ({2016}), "Consistent evaluation of ACOS-GOSAT, BESD-SCIAMACHY, CarbonTracker, and MACC through comparisons to TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({2}), pp. 683-709. |
| Abstract: Consistent validation of satellite CO2 estimates is a prerequisite for using multiple satellite CO2 measurements for joint flux inversion, and for establishing an accurate long-term atmospheric CO2 data record. Harmonizing satellite CO2 measurements is particularly important since the differences in instruments, observing geometries, sampling strategies, etc. imbue different measurement characteristics in the various satellite CO2 data products. We focus on validating model and satellite observation attributes that impact flux estimates and CO2 assimilation, including accurate error estimates, correlated and random errors, overall biases, biases by season and latitude, the impact of coincidence criteria, validation of seasonal cycle phase and amplitude, yearly growth, and daily variability. We evaluate dry-air mole fraction (X-CO2) for Greenhouse gases Observing SATellite (GOSAT) (Atmospheric CO2 Observations from Space, ACOS b3.5) and SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) (Bremen Optimal Estimation DOAS, BESD v2.00.08) as well as the CarbonTracker (CT2013b) simulated CO2 mole fraction fields and the Monitoring Atmospheric Composition and Climate (MACC) CO2 inversion system (v13.1) and compare these to Total Carbon Column Observing Network (TCCON) observations (GGG2012/2014). We find standard deviations of 0.9, 0.9, 1.7, and 2.1 ppm vs. TCCON for CT2013b, MACC, GOSAT, and SCIAMACHY, respectively, with the single observation errors 1.9 and 0.9 times the predicted errors for GOSAT and SCIAMACHY, respectively. We quantify how satellite error drops with data averaging by interpreting according to error(2) = a(2) + b(2) / n (with n being the number of observations averaged, a the systematic (correlated) errors, and b the random (uncorrelated) errors). a and b are estimated by satellites, coincidence criteria, and hemisphere. Biases at individual stations have year-to-year variability of similar to 0.3 ppm, with biases larger than the TCCON-predicted bias uncertainty of 0.4 ppm at many stations. We find that GOSAT and CT2013b underpredict the seasonal cycle amplitude in the Northern Hemisphere (NH) between 46 and 53 degrees N, MACC overpredicts between 26 and 37 ffi N, and CT2013b underpredicts the seasonal cycle amplitude in the Southern Hemisphere (SH). The seasonal cycle phase indicates whether a data set or model lags another data set in time. We find that the GOSAT measurements improve the seasonal cycle phase substantially over the prior while SCIAMACHY measurements improve the phase significantly for just two of seven sites. The models reproduce the measured seasonal cycle phase well except for at Lauder125HR (CT2013b) and Darwin (MACC). We compare the variability within 1 day between TCCON and models in JJA; there is correlation between 0.2 and 0.8 in the NH, with models showing 10-50% the variability of TCCON at different stations and CT2013b showing more variability than MACC. This paper highlights findings that provide inputs to estimate flux errors in model assimilations, and places where models and satellites need further investigation, e.g., the SH for models and 4567 ffi N for GOSAT and CT2013b. |
BibTeX:
@article{kulawik16a,
author = {Kulawik, Susan and Wunch, Debra and O'Dell, Christopher and Frankenberg, Christian and Reuter, Maximilian and Oda, Tomohiro and Chevallier, Frederic and Sherlock, Vanessa and Buchwitz, Michael and Osterman, Greg and Miller, Charles E. and Wennberg, Paul O. and Griffith, David and Morino, Isamu and Dubey, Manvendra K. and Deutscher, Nicholas M. and Notholt, Justus and Hase, Frank and Warneke, Thorsten and Sussmann, Ralf and Robinson, John and Strong, Kimberly and Schneider, Matthias and De Maziere, Martine and Shiomi, Kei and Feist, Dietrich G. and Iraci, Laura T. and Wolf, Joyce},
title = {Consistent evaluation of ACOS-GOSAT, BESD-SCIAMACHY, CarbonTracker, and MACC through comparisons to TCCON},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2016},
volume = {9},
number = {2},
pages = {683--709},
doi = {10.5194/amt-9-683-2016}
}
|
| Kulawik SS, O'Dell C, Payne VH, Kuai L, Worden HM, Biraud SC, Sweeney C, Stephens B, Iraci LT, Yates EL and Tanaka T ({2017}), "Lower-tropospheric CO2 from near-infrared ACOS-GOSAT observations", ATMOSPHERIC CHEMISTRY AND PHYSICS., APR 27, {2017}. Vol. {17}({8}), pp. 5407-5438. |
| Abstract: We present two new products from near-infrared Greenhouse Gases Observing Satellite (GOSAT) observations: lowermost tropospheric (LMT, from 0 to 2.5 km) and upper tropospheric-stratospheric (U, above 2.5 km) carbon dioxide partial column mixing ratios. We compare these new products to aircraft profiles and remote surface flask measurements and find that the seasonal and year-to-year variations in the new partial column mixing ratios significantly improve upon the Atmospheric CO2 Observations from Space (ACOS) and GOSAT (ACOS-GOSAT) initial guess and/or a priori, with distinct patterns in the LMT and U seasonal cycles that match validation data. For land monthly averages, we find errors of 1.9, 0.7, and 0.8 ppm for retrieved GOSAT LMT, U, and X CO2; for ocean monthly averages, we find errors of 0.7, 0.5, and 0.5 ppm for retrieved GOSAT LMT, U, and X CO2. In the southern hemispheric biomass burning season, the new partial columns show similar patterns to MODIS fire maps and MOPITT multispectral CO for both vertical levels, despite a flat ACOS-GOSAT prior, and a CO-CO2 emission factor comparable to published values. The difference of LMT and U, useful for evaluation of model transport error, has also been validated with a monthly average error of 0.8 (1.4) ppm for ocean (land). LMT is more locally influenced than U, meaning that local fluxes can now be better separated from CO2 transported from far away. |
BibTeX:
@article{kulawik17a,
author = {Kulawik, Susan S. and O'Dell, Chris and Payne, Vivienne H. and Kuai, Le and Worden, Helen M. and Biraud, Sebastien C. and Sweeney, Colm and Stephens, Britton and Iraci, Laura T. and Yates, Emma L. and Tanaka, Tomoaki},
title = {Lower-tropospheric CO2 from near-infrared ACOS-GOSAT observations},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {8},
pages = {5407--5438},
doi = {10.5194/acp-17-5407-2017}
}
|
| Kumar KR, Tiwari YK, Valsala V and Murtugudde R ({2014}), "On understanding the land-ocean CO2 contrast over the Bay of Bengal: A case study during 2009 summer monsoon", ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH., APR, {2014}. Vol. {21}({7}), pp. 5066-5075. |
| Abstract: Ship-based observations of atmospheric carbon dioxide (CO2) concentration over the Bay of Bengal (BoB) between 17 July 2009 and 17 Aug 2009 offered an excellent opportunity to evaluate the land-ocean contrast of surface CO2 and facilitated its comparison with model simulated CO2 concentrations. Elevated values of CO2 with large variability near the coastal region and relatively low values with correspondingly lower variability over the open ocean suggest that this observed CO2 variability over the ocean essentially captures the differences in terrestrial and oceanic CO2 fluxes. Although the region under investigation is well known for its atmospheric intraseasonal oscillations of Indian summer monsoon during July and August, the limited duration of observations performed from a moving ship in a research cruise, is not able to capture any high-frequency variability of atmospheric CO2 concentrations. But band-passed sea surface temperature and wind anomalies do indicate strong intraseasonal variability over the study region during the observational period. The synoptic data, albeit quite short in duration, thus offer a clear benchmark for abrupt variability of CO2 concentration between land and ocean. |
BibTeX:
@article{kumar14a,
author = {Kumar, K. Ravi and Tiwari, Yogesh K. and Valsala, Vinu and Murtugudde, Raghu},
title = {On understanding the land-ocean CO2 contrast over the Bay of Bengal: A case study during 2009 summer monsoon},
journal = {ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH},
year = {2014},
volume = {21},
number = {7},
pages = {5066--5075},
doi = {10.1007/s11356-013-2386-2}
}
|
| Kumar KR, Valsala V, Tiwari YK, Revadekar JV, Pillai P, Chakraborty S and Murtugudde R ({2016}), "Intra-seasonal variability of atmospheric CO2 concentrations over India during summer monsoons", ATMOSPHERIC ENVIRONMENT., OCT, {2016}. Vol. {142}, pp. 229-237. |
| Abstract: In a study based on a data assimilation product of the terrestrial biospheric fluxes of CO2 over India, the subcontinent was hypothesized to be an anomalous source (sink) of CO2 during the active (break) spells of rain in the summer monsoon from June to September (Valsala et al., 2013). We test this hypothesis here by investigating intraseasonal variability in the atmospheric CO2 concentrations over India by utilizing a combination of ground-based and satellite observations and model outputs. The results show that the atmospheric CO2 concentration also varies in synchrony with the active and break spells of rainfall with amplitude of +/- 2 ppm which is above the instrumental uncertainty of the present day techniques of atmospheric CO2 measurements. The result is also consistent with the signs of the Net Ecosystem Exchange (NEE) flux anomalies estimated in our earlier work. The study thus offers the first observational affirmation of the above hypothesis although the data gap in the satellite measurements during monsoon season and the limited ground-based stations over India still leaves some uncertainty in the robust assertion of the hypothesis. The study highlights the need to capture these subtle variabilities and their responses to climate variability and change since it has implications for inverse estimates of terrestrial CO2 fluxes. (C) 2016 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{kumar16a,
author = {Kumar, K. Ravi and Valsala, Vinu and Tiwari, Yogesh K. and Revadekar, J. V. and Pillai, Prasanth and Chakraborty, Supriyo and Murtugudde, Raghu},
title = {Intra-seasonal variability of atmospheric CO2 concentrations over India during summer monsoons},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2016},
volume = {142},
pages = {229--237},
doi = {10.1016/j.atmosenv.2016.07.023}
}
|
| Kurz WA, Shaw CH, Boisvenue C, Stinson G, Metsaranta J, Leckie D, Dyk A, Smyth C and Neilson ET ({2013}), "Carbon in Canada's boreal forest - A synthesis", ENVIRONMENTAL REVIEWS. Vol. {21}({4}), pp. 260-292. |
| Abstract: Canada's managed boreal forest, 54% of the nation's total boreal forest area, stores 28 Pg carbon (C) in biomass, dead organic matter, and soil pools. The net C balance is dominated by the difference of two large continuous fluxes: C uptake (net primary production) and release during decomposition (heterotrophic respiration). Additional releases of C can be high in years, or in areas, that experience large anthropogenic or natural disturbances. From 1990 to 2008, Canada's managed boreal forest has acted as C sink of 28 Tg C year(-1), removing CO2 from the atmosphere to replace the 17 Tg of C annually harvested and store an additional 11 Tg of C year-1 in ecosystem C pools. A large fraction (similar to 57 of the C harvested since 1990 remains stored in wood products and solid waste disposal sites in Canada and abroad, replacing C emitted from the decay or burning of wood harvested prior to 1990 and contributing to net increases in product and landfill C pools. Wood product use has reduced emissions in other sectors by substituting for emission-intensive products (concrete, steel). The C balance of the unmanaged boreal forest is currently unknown. The future C balance of the Canadian boreal forest will affect the global atmospheric C budget and influence the mitigation efforts required to attain atmospheric CO2 stabilization targets. The single biggest threat to C stocks is human-caused climate change. Large C stocks have accumulated in the boreal because decomposition is limited by cold temperatures and often anoxic environments. Increases in temperatures and disturbance rates could result in a large net C source during the remainder of this century and beyond. Uncertainties about the impacts of global change remain high, but we emphasize the asymmetry of risk: sustained large-scale increases in productivity are unlikely to be of sufficient magnitude to offset higher emissions from increased disturbances and heterotrophic respiration. Reducing the uncertainties of the current and future C balance of Canada's 270 Mha of boreal forest requires addressing gaps in monitoring, observation, and quantification of forest C dynamics, with particular attention to 125 Mha of unmanaged boreal forest with extensive areas of deep organic soils, peatlands, and permafrost containing large quantities of C that are vulnerable to global warming. |
BibTeX:
@article{kurz13a,
author = {Kurz, W. A. and Shaw, C. H. and Boisvenue, C. and Stinson, G. and Metsaranta, J. and Leckie, D. and Dyk, A. and Smyth, C. and Neilson, E. T.},
title = {Carbon in Canada's boreal forest - A synthesis},
journal = {ENVIRONMENTAL REVIEWS},
year = {2013},
volume = {21},
number = {4},
pages = {260--292},
doi = {10.1139/er-2013-0041}
}
|
| LaFranchi BW, McFarlane KJ, Miller JB, Lehman SJ, Phillips CL, Andrews AE, Tans PP, Chen H, Liu Z, Turnbull JC, Xu X and Guilderson TP ({2016}), "Strong regional atmospheric C-14 signature of respired CO2 observed from a tall tower over the midwestern United States", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., AUG, {2016}. Vol. {121}({8}), pp. 2275-2295. |
| Abstract: Radiocarbon in CO2 ((CO2)-C-14) measurements can aid in discriminating between fast (< 1 year) and slower (> 5-10 years) cycling of C between the atmosphere and the terrestrial biosphere due to the 14C disequilibrium between atmospheric and terrestrial C. However, (CO2)-C-14 in the atmosphere is typically much more strongly impacted by fossil fuel emissions of CO2, and, thus, observations often provide little additional constraints on respiratory flux estimates at regional scales. Here we describe a data set of (CO2)-C-14 observations from a tall tower in northern Wisconsin (USA) where fossil fuel influence is far enough removed that during the summer months, the biospheric component of the (CO2)-C-14 budget dominates. We find that the terrestrial biosphere is responsible for a significant contribution to (CO2)-C-14 that is 2-3 times higher than predicted by the Carnegie-Ames-Stanford approach terrestrial ecosystem model for observations made in 2010. This likely includes a substantial contribution from the North American boreal ecoregion, but transported biospheric emissions from outside the model domain cannot be ruled out. The (CO2)-C-14 enhancement also appears somewhat decreased in observations made over subsequent years, suggesting that 2010 may be anomalous. With these caveats acknowledged, we discuss the implications of the observation/ model comparison in terms of possible systematic biases in the model versus short-term anomalies in the observations. Going forward, this isotopic signal could be exploited as an important indicator to better constrain both the long-term carbon balance of terrestrial ecosystems and the short-term impact of disturbance-based loss of carbon to the atmosphere. |
BibTeX:
@article{lafranchi16a,
author = {LaFranchi, B. W. and McFarlane, K. J. and Miller, J. B. and Lehman, S. J. and Phillips, C. L. and Andrews, A. E. and Tans, P. P. and Chen, H. and Liu, Z. and Turnbull, J. C. and Xu, X. and Guilderson, T. P.},
title = {Strong regional atmospheric C-14 signature of respired CO2 observed from a tall tower over the midwestern United States},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2016},
volume = {121},
number = {8},
pages = {2275--2295},
doi = {10.1002/2015JG003271}
}
|
| Lan X, Tans P, Sweeney C, Andrews A, Jacobson A, Crotwell M, Dlugokencky E, Kofler J, Lang P, Thoning K and Wolter S ({2017}), "Gradients of column CO2 across North America from the NOAA Global Greenhouse Gas Reference Network", ATMOSPHERIC CHEMISTRY AND PHYSICS., DEC 21, {2017}. Vol. {17}({24}), pp. 15151-15165. |
| Abstract: This study analyzes seasonal and spatial patterns of column carbon dioxide (CO2) over North America, calculated from aircraft and tall tower measurements from the NOAA Global Greenhouse Gas Reference Network from 2004 to 2014. Consistent with expectations, gradients between the eight regions studied are larger below 2 km than above 5 km. The 11-year mean CO2 dry mole fraction (XCO2) in the column below similar to 330 hPa (similar to 8 km above sea level) from NOAA's CO2 data assimilation model, Carbon-Tracker (CT2015), demonstrates good agreement with those calculated from calibrated measurements on aircraft and towers. Total column XCO2 was attained by combining modeled CO2 above 330 hPa from CT2015 with the measurements. We find large spatial gradients of total column XCO2 from June to August, with north and northeast regions having similar to 3 ppm stronger summer drawdown (peak-to-valley amplitude in seasonal cycle) than the south and southwest regions. The long-term averaged spatial gradients of total column XCO2 across North America show a smooth pattern that mainly reflects the large-scale circulation. We have conducted a CarbonTracker experiment to investigate the impact of Eurasian long-range transport. The result suggests that the large summertime Eurasian boreal flux contributes about half of the north-south column XCO2 gradient across North America. Our results confirm that continental-scale total column XCO2 gradients simulated by CarbonTracker are realistic and can be used to evaluate the credibility of some spatial patterns from satellite retrievals, such as the long-term average of growing-season spatial patterns from satellite retrievals reported for Europe which show a larger spatial difference (similar to 6 ppm) and scattered hot spots. |
BibTeX:
@article{lan17a,
author = {Lan, Xin and Tans, Pieter and Sweeney, Colm and Andrews, Arlyn and Jacobson, Andrew and Crotwell, Molly and Dlugokencky, Edward and Kofler, Jonathan and Lang, Patricia and Thoning, Kirk and Wolter, Sonja},
title = {Gradients of column CO2 across North America from the NOAA Global Greenhouse Gas Reference Network},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {24},
pages = {15151--15165},
doi = {10.5194/acp-17-15151-2017}
}
|
| de lange A and Landgraf J ({2018}), "Methane profiles from GOSAT thermal infrared spectra", ATMOSPHERIC MEASUREMENT TECHNIQUES., JUN 28, {2018}. Vol. {11}({6}), pp. {3815-3828}. |
| Abstract: This paper discusses the retrieval of atmospheric methane profiles from the thermal infrared band of the Japanese Greenhouse Gases Observing Satellite (GOSAT) between 1210 and 1310 cm(-1), using the RemoTeC analysis software. Approximately one degree of information on the vertical methane distribution is inferred from the measurements, with the main sensitivity at about 9 km altitude but little sensitivity to methane in the lower troposphere. For verification, we compare the GOSAT-TIR methane profile retrieval results with profiles from model fields provided by the Monitoring Atmospheric Composition and Climate (MACC) project, scaled to the total column measurements of the Total Carbon Column Observing Network (TCCON) at ground-based measurement sites. Without any radiometric corrections of GOSAT observations, differences between both data sets can be as large as 10 %. To mitigate these differences, we developed a correction scheme using a principal component analysis of spectral fit residuals and airborne observations of methane during the HIAPER pole-to-pole observations (HIPPO) campaign II and III. When the correction scheme is applied, the bias in the methane profile can be reduced to less than 2% over the whole altitude range with respect to MACC model methane fields. Furthermore, we show that, with this correction, the retrievals result in smooth methane fields over land and ocean crossings and no differences can be discerned between daytime and night-time measurements. Finally, a cloud filter is developed for the nighttime and ocean measurements. This filter is rooted in the GOSAT-TIR (thermal infrared) measurements and its performance, in terms of biases, is consistent with the cloud filter based on the GOSAT-SWIR (shortwave infrared) measurements. The TIR filter shows a higher acceptance rate of observations than the SWIR filter, at the cost of a higher uncertainty in the retrieved methane profiles. |
BibTeX:
@article{lange18a,
author = {de lange, Arno and Landgraf, Jochen},
title = {Methane profiles from GOSAT thermal infrared spectra},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2018},
volume = {11},
number = {6},
pages = {3815-3828},
doi = {{10.5194/amt-11-3815-2018}}
}
|
| Langley B (2012), "Modelling urban forest structure and services using the urban forest effects (UFORE) model". Thesis at: University of British Columbia. |
BibTeX:
@jurthesis{langley12a,
author = {Langley, Benjamin},
title = {Modelling urban forest structure and services using the urban forest effects (UFORE) model},
school = {University of British Columbia},
year = {2012},
url = {https://open.library.ubc.ca/collections/undergraduateresearch/52966/items/1.0075544}
}
|
| Lanso AS, Bendtsen J, Christensen JH, Sorensen LL, Chen H, Meijer HAJ and Geels C ({2015}), "Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability", BIOGEOSCIENCES. Vol. {12}({9}), pp. 2753-2772. |
| Abstract: Minimising the uncertainties in estimates of air-sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air-sea CO2 flux along with its sensitivity to, for example, short-term temporal variability in wind speed, atmospheric mixing height and atmospheric CO2 concentration. With this study, the importance of high spatiotemporal resolution of atmospheric parameters for the air-sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO(2)(w)) has been developed for this coastal area based on available data from monitoring stations and on-board pCO(2)(w) measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air-sea CO2 flux. Two model simulations were conducted - one including short-term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air-sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005-2010, the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish straits and Kattegat was 287 and 471 Gg C yr(-1) for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr(-1) was found to be significant, and thus ignoring short-term variability in atmospheric CO2 does have a sizeable effect on the air-sea CO2 exchange. The combination of the atmospheric model and the new pCO(2)(w) fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr(-1) was found for the Danish waters. A large uncertainty is connected to the air-sea CO2 flux in particular caused by the transfer velocity parameterisation and the applied pCO(2)(w) climatology. However, as a significant difference of 184 Gg C yr(-1) is obtained between the VAT and CAT simulations, the present study underlines the importance of including short-term variability in atmospheric CO2 concentration in future model studies of the air-sea exchange in order to minimise the uncertainty. |
BibTeX:
@article{lanso15a,
author = {Lanso, A. S. and Bendtsen, J. and Christensen, J. H. and Sorensen, L. L. and Chen, H. and Meijer, H. A. J. and Geels, C.},
title = {Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability},
journal = {BIOGEOSCIENCES},
year = {2015},
volume = {12},
number = {9},
pages = {2753--2772},
doi = {10.5194/bg-12-2753-2015}
}
|
| Lanso AS, Sorensen LL, Christensen JH, Rutgersson A and Geels C ({2017}), "The influence of short-term variability in surface water pCO(2) on modelled air-sea CO2 exchange", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {69} |
| Abstract: Coastal seas and estuarine systems are highly variable in both time and space and with their heterogeneity difficult to capture with measurements. Models are useful tools in obtaining a better spatiotemporal coverage or, at least, a better understanding of the impacts such heterogeneity has in driving variability in coastal oceans and estuaries. A model-based sensitivity study is constructed in this study in order to examine the effects of short-term variability in surface water pCO(2) on the annual air-sea CO2 exchange in coastal regions. An atmospheric transport model formed the basis of the modelling framework for the study of the Baltic Sea and the Danish inner waters. Several maps of surface water pCO(2) were employed in the modelling framework. While a monthly Baltic Sea climatology (BSC) had already been developed, the current study further extended this with the addition of an improved near-coastal climatology for the Danish inner waters. Furthermore, daily surface fields of pCO(2) were obtained from a mixed layer scheme constrained by surface measurements of pCO(2) (JENA). Short-term variability in surface water pCO(2) was assessed by calculating monthly mean diurnal cycles from continuous measurements of surface water pCO(2), observed at stationary sites within the Baltic Sea. No apparent diurnal cycle was evident in winter, but diurnal cycles (with amplitudes up to 27 mu atm) were found from April to October. The present study showed that the temporal resolution of surface water pCO(2) played an influential role on the annual air-sea CO2 exchange for the coastal study region. Hence, annual estimates of CO2 exchanges are sensitive to variation on much shorter time scales, and this variability should be included for any model study investigating the exchange of CO2 across the air-sea interface. Furthermore, the choice of surface pCO(2) maps also had a crucial influence on the simulated air-sea CO2 exchange. |
BibTeX:
@article{lanso17a,
author = {Lanso, Anne Sofie and Sorensen, Lise Lotte and Christensen, Jesper H. and Rutgersson, Anna and Geels, Camilla},
title = {The influence of short-term variability in surface water pCO(2) on modelled air-sea CO2 exchange},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2017},
volume = {69},
doi = {10.1080/16000889.2017.1302670}
}
|
| Laskar AH, Lin L-C, Jiang X and Liang M-C (2018), "Distribution of CO2 in Western Pacific, Studied Using Isotope Data Made in Taiwan, OCO‐2 Satellite Retrievals, and CarbonTracker Products", Earth and Space Science. |
BibTeX:
@article{laskar18a,
author = {Amzad H. Laskar and Li-Ching Lin and Xun Jiang and Mao-Chang Liang},
title = {Distribution of CO2 in Western Pacific, Studied Using Isotope Data Made in Taiwan, OCO‐2 Satellite Retrievals, and CarbonTracker Products},
journal = {Earth and Space Science},
year = {2018},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018EA000415}
}
|
| Lauvaux T, Schuh AE, Uliasz M, Richardson S, Miles N, Andrews AE, Sweeney C, Diaz LI, Martins D, Shepson PB and Davis KJ ({2012}), "Constraining the CO2 budget of the corn belt: exploring uncertainties from the assumptions in a mesoscale inverse system", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({1}), pp. 337-354. |
| Abstract: We performed an atmospheric inversion of the CO2 fluxes over Iowa and the surrounding states, from June to December 2007, at 20 km resolution and weekly timescale. Eight concentration towers were used to constrain the carbon balance in a 1000x1000 km(2) domain in this agricultural region of the US upper midwest. The CO2 concentrations of the boundaries derived from CarbonTracker were adjusted to match direct observations from aircraft profiles around the domain. The regional carbon balance ends up with a sink of 183 Tg C +/- 35 Tg C over the area for the period June-December, 2007. Potential bias from incorrect boundary conditions of about 0.55 ppm over the 7 months was corrected using mixing ratios from four different aircraft profile sites operated at a weekly time scale, acting as an additional source of uncertainty of 24 Tg C. We used two different prior flux estimates, the SiBCrop model and the inverse flux product from the CarbonTracker system. We show that inverse flux estimates using both priors converge to similar posterior estimates (20 Tg C difference), in our reference inversion, but some spatial structures from the prior fluxes remain in the posterior fluxes, revealing the importance of the prior flux resolution and distribution despite the large amount of atmospheric data available. The retrieved fluxes were compared to eddy flux towers in the corn and grassland areas, revealing an improvement in the seasonal cycles between the two compared to the prior fluxes, despite large absolute differences due to representation errors. The uncertainty of 34 Tg C (or 34 g C m(2)) was derived from the posterior uncertainty obtained with our reference inversion of about 25 to 30 Tg C and from sensitivity tests of the assumptions made in the inverse system, for a mean carbon balance over the region of -183 Tg C, slightly weaker than the reference. Because of the potential large bias (similar to 24 Tg C in this case) due to choice of background conditions, proportional to the surface but not to the regional flux, this methodology seems limited to regions with a large signal (sink or source), unless additional observations can be used to constrain the boundary inflow. |
BibTeX:
@article{lauvaux12a,
author = {Lauvaux, T. and Schuh, A. E. and Uliasz, M. and Richardson, S. and Miles, N. and Andrews, A. E. and Sweeney, C. and Diaz, L. I. and Martins, D. and Shepson, P. B. and Davis, K. J.},
title = {Constraining the CO2 budget of the corn belt: exploring uncertainties from the assumptions in a mesoscale inverse system},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2012},
volume = {12},
number = {1},
pages = {337--354},
doi = {10.5194/acp-12-337-2012}
}
|
| Lauvaux T, Schuh AE, Bocquet M, Wu L, Richardson S, Miles N and Davis KJ ({2012}), "Network design for mesoscale inversions of CO2 sources and sinks", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {64} |
| Abstract: Recent instrumental deployments of regional observation networks of atmospheric CO2 mixing ratios have been used to constrain carbon sources and sinks using inversion methodologies. In this study, we performed sensitivity experiments using observation sites from the Mid Continent Intensive experiment to evaluate the required spatial density and locations of CO2 concentration towers based on flux corrections and error reduction analysis. In addition, we investigated the impact of prior flux error structures with different correlation lengths and biome information. We show here that, while the regional carbon balance converged to similar annual estimates using only two concentration towers over the region, additional sites were necessary to retrieve the spatial flux distribution of our reference case (using the entire network of eight towers). Local flux corrections required the presence of observation sites in their vicinity, suggesting that each tower was only able to retrieve major corrections within a hundred of kilometres around, despite the introduction of spatial correlation lengths (similar to 100 to 300 km) in the prior flux errors. We then quantified and evaluated the impact of the spatial correlations in the prior flux errors by estimating the improvement in the CO2 model-data mismatch of the towers not included in the inversion. The overall gain across the domain increased with the correlation length, up to 300 km, including both biome-related and non-biome-related structures. However, the spatial variability at smaller scales was not improved. We conclude that the placement of observation towers around major sources and sinks is critical for regional-scale inversions in order to obtain reliable flux distributions in space. Sparser networks seem sufficient to assess the overall regional carbon budget with the support of flux error correlations, indicating that regional signals can be recovered using hourly mixing ratios. However, the smaller spatial structures in the posterior fluxes are highly constrained by assumed prior flux error correlation lengths, with no significant improvement at only a few hundreds of kilometres away from the observation sites. |
BibTeX:
@article{lauvaux12b,
author = {Lauvaux, T. and Schuh, A. E. and Bocquet, M. and Wu, L. and Richardson, S. and Miles, N. and Davis, K. J.},
title = {Network design for mesoscale inversions of CO2 sources and sinks},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2012},
volume = {64},
doi = {10.3402/tellusb.v64i0.17980}
}
|
| Lauvaux T, Miles NL, Richardson SJ, Deng A, Stauffer DR, Davis KJ, Jacobson G, Rella C, Calonder G-P and DeCola PL ({2013}), "Urban Emissions of CO2 from Davos, Switzerland: The First Real-Time Monitoring System Using an Atmospheric Inversion Technique", JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY., DEC, {2013}. Vol. {52}({12}), pp. 2654-2668. |
| Abstract: Anthropogenic emissions from urban areas represent 70% of the fossil fuel carbon emitted globally according to carbon emission inventories. The authors present here the first operational system able to monitor in near-real time daily emission estimates, using a mesoscale atmospheric inversion framework over the city of Davos, Switzerland, before, during, and after the World Economic Forum 2012 Meeting (WEF-2012). Two instruments that continuously measured atmospheric mixing ratios of greenhouse gases (GHGs) were deployed at two locations from 23 December 2011 to 3 March 2012: one site was located in the urban area and the other was out of the valley in the surrounding mountains. Carbon dioxide, methane, and carbon monoxide were measured continuously at both sites. The Weather Research and Forecasting mesoscale atmospheric model (WRF), in four-dimensional data assimilation mode, was used to simulate the transport of GHGs over the valley of Davos at 1.3-km resolution. Wintertime emissions prior to the WEF-2012 were about 40% higher than the initial annual inventory estimate, corresponding to the use of heating fuel in the winter. Daily inverse fluxes were highly correlated with the local climate, especially during the severe cold wave that affected most of Europe in early February 2012. During the WEF-2012, emissions dropped by 35% relative to the first month of the deployment, despite similar temperatures and the presence of several thousand participants at the meeting. On the basis of composite diurnal cycles of hourly CO/CO2 ratios, the absence of traffic peaks during the WEF-2012 meeting indicated that change in road emissions is potentially responsible for the observed decrease in the city emissions during the meeting. |
BibTeX:
@article{lauvaux13a,
author = {Lauvaux, Thomas and Miles, Natasha L. and Richardson, Scott J. and Deng, Aijun and Stauffer, David R. and Davis, Kenneth J. and Jacobson, Gloria and Rella, Chris and Calonder, Gian-Paul and DeCola, Philip L.},
title = {Urban Emissions of CO2 from Davos, Switzerland: The First Real-Time Monitoring System Using an Atmospheric Inversion Technique},
journal = {JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY},
year = {2013},
volume = {52},
number = {12},
pages = {2654--2668},
doi = {10.1175/JAMC-D-13-038.1}
}
|
| Lauvaux T, Miles NL, Deng A, Richardson SJ, Cambaliza MO, Davis KJ, Gaudet B, Gurney KR, Huang J, O'Keefe D, Song Y, Karion A, Oda T, Patarasuk R, Razlivanov I, Sarmiento D, Shepson P, Sweeney C, Turnbull J and Wu K ({2016}), "High-resolution atmospheric inversion of urban CO2 emissions during the dormant season of the Indianapolis Flux Experiment (INFLUX)", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 27, {2016}. Vol. {121}({10}), pp. 5213-5236. |
| Abstract: Based on a uniquely dense network of surface towers measuring continuously the atmospheric concentrations of greenhouse gases (GHGs), we developed the first comprehensive monitoring systems of CO2 emissions at high resolution over the city of Indianapolis. The urban inversion evaluated over the 2012-2013 dormant season showed a statistically significant increase of about 20% (from 4.5 to 5.7 MtC +/- 0.23 MtC) compared to the Hestia CO2 emission estimate, a state-of-the-art building-level emission product. Spatial structures in prior emission errors, mostly undetermined, appeared to affect the spatial pattern in the inverse solution and the total carbon budget over the entire area by up to 15 while the inverse solution remains fairly insensitive to the CO2 boundary inflow and to the different prior emissions (i.e., ODIAC). Preceding the surface emission optimization, we improved the atmospheric simulations using a meteorological data assimilation system also informing our Bayesian inversion system through updated observations error variances. Finally, we estimated the uncertainties associated with undetermined parameters using an ensemble of inversions. The total CO2 emissions based on the ensemble mean and quartiles (5.26-5.91 MtC) were statistically different compared to the prior total emissions (4.1 to 4.5 MtC). Considering the relatively small sensitivity to the different parameters, we conclude that atmospheric inversions are potentially able to constrain the carbon budget of the city, assuming sufficient data to measure the inflow of GHG over the city, but additional information on prior emission error structures are required to determine the spatial structures of urban emissions at high resolution. |
BibTeX:
@article{lauvaux16a,
author = {Lauvaux, Thomas and Miles, Natasha L. and Deng, Aijun and Richardson, Scott J. and Cambaliza, Maria O. and Davis, Kenneth J. and Gaudet, Brian and Gurney, Kevin R. and Huang, Jianhua and O'Keefe, Darragh and Song, Yang and Karion, Anna and Oda, Tomohiro and Patarasuk, Risa and Razlivanov, Igor and Sarmiento, Daniel and Shepson, Paul and Sweeney, Colm and Turnbull, Jocelyn and Wu, Kai},
title = {High-resolution atmospheric inversion of urban CO2 emissions during the dormant season of the Indianapolis Flux Experiment (INFLUX)},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2016},
volume = {121},
number = {10},
pages = {5213--5236},
doi = {10.1002/2015JD024473}
}
|
| Law RM, Steele LP, Krummel PB and Zahorowski W ({2010}), "Synoptic variations in atmospheric CO2 at Cape Grim: a model intercomparison", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 810-820. |
| Abstract: A `TransCom' model intercomparison is used to assess how well synoptic and diurnal variations of carbon dioxide (CO2) and 222Rn (radon) can be modelled at the coastal site, Cape Grim, Australia. Each model was run with prescribed fluxes and forced with analysed meteorology for 2000-2003. Twelve models were chosen for analysis based on each model's ability to differentiate baseline CO2 concentrations from non-baseline CO2 (influenced by regional land fluxes). Analysis focused on non-baseline events during 2002-2003. Radon was better simulated than CO2, indicating that a spatially uniform radon land flux is a reasonable assumption and that regional-scale transport was adequately captured by the models. For both radon and CO2, the ensemble model mean generally performed better than any individual model. Two case studies highlight common problems with the simulations. First, in summer and autumn the Cape Grim observations are sometimes influenced by Tasmanian rather than mainland Australian fluxes. These periods are poorly simulated. Secondly, an event with an urban plume demonstrates how the relatively low spatial resolution of the input CO2 fluxes limits the quality of the simulations. Analysis of periods with below baseline concentration indicates the possible influence of carbon uptake by winter crops in southern mainland Australia. |
BibTeX:
@article{law10a,
author = {Law, Rachel M. and Steele, L. Paul and Krummel, Paul B. and Zahorowski, Wlodek},
title = {Synoptic variations in atmospheric CO2 at Cape Grim: a model intercomparison},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2010},
volume = {62},
number = {5, SI},
pages = {810--820},
doi = {10.1111/j.1600-0889.2010.00470.x}
}
|
| Lee TR, De Wekker SFJ, Andrews AE, Kofler J and Williams J ({2012}), "Carbon dioxide variability during cold front passages and fair weather days at a forested mountaintop site", ATMOSPHERIC ENVIRONMENT., JAN, {2012}. Vol. {46}, pp. 405-416. |
| Abstract: This study describes temporal carbon dioxide (CO2) changes at a new meteorological site on a mountaintop in the Virginia Blue Ridge Mountains during the first year of measurements. Continental mountaintop locations are increasingly being used for CO2 monitoring, and investigations are needed to better understand measurements made at these locations. We focus on CO2 mixing ratio changes on days with cold front passages and on fair weather days. Changes in CO2 mixing ratios are largest during cold front passages outside the growing season and on clear, fair weather days in the growing season. 67% (60 of the frontal passages during the non-growing (growing) season have larger postfrontal than prefrontal CO2 mixing ratios. The increase in CO2 mixing ratio around the frontal passage is short-lived and coincides with changes in CO and O-3. The CO2 increase can therefore be used as an additional criterion to determine the timing of frontal passages at the mountaintop station. The CO2 increase can be explained by an accumulation of trace gases along frontal boundaries. The magnitude and duration of the CO2 increase is affected by the wind speed and direction that determine the source region of the postfrontal air. Southward-moving fronts result in the largest prolonged period of elevated CO2, consistent with the postfrontal advection of air from the Northeastern United States where anthropogenic contributions are relatively large compared to other areas in the footprint of the mountaintop station. These anthropogenic contributions to the CO2 changes are confirmed through concurrent CO measurements and output from NOAA's CarbonTracker model. (C) 2011 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{lee12a,
author = {Lee, Temple R. and De Wekker, Stephan F. J. and Andrews, Arlyn E. and Kofler, Jonathan and Williams, Jonathan},
title = {Carbon dioxide variability during cold front passages and fair weather days at a forested mountaintop site},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2012},
volume = {46},
pages = {405--416},
doi = {10.1016/j.atmosenv.2011.09.068}
}
|
| Lee TR, De Wekker SFJ, Pal S, Andrews AE and Kofler J ({2015}), "Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {67} |
| Abstract: The variability of trace gases such as carbon monoxide (CO) at surface monitoring stations is affected by meteorological forcings that are particularly complicated over mountainous terrain. A detailed understanding of the impact of meteorological forcings on trace gas variability is challenging, but is vital to distinguish trace gas measurements affected by local pollutant sources from measurements representative of background mixing ratios. In the present study, we investigate the meteorological and CO characteristics at Pinnacles (38.61 N, 78.35 W, 1017m above mean sea level), a mountaintop monitoring site in northwestern Virginia, USA, in the Appalachian Mountains, from 2009 to 2012, and focus on understanding the dominant meteorological forcings affecting the CO variability on diurnal timescales. The annual mean diurnal CO cycle shows a minimum in the morning between 0700 and 0900 LST and a maximum in the late afternoon between 1600 and 2000 LST, with a mean (median) daily CO amplitude of 39.2 +/- 23.7 ppb (33.2 ppb). CO amplitudes show large day-to-day variability. The largest CO amplitudes, in which CO mixing ratios can change >100 ppb in >3 h, occur in the presence of synoptic disturbances. Under fair weather conditions, local-to regional-scale transport processes are found to be more important drivers of the diurnal CO variability. On fair weather days with northwesterly winds, boundary layer dilution causes a daytime CO decrease, resembling the variability observed atop tall towers in flat terrain. Fair weather days with a wind shift from the northwest to the south are characterised by an afternoon CO increase and resemble the variability observed at mountaintops influenced by the vertical transport of polluted air from adjacent valleys. |
BibTeX:
@article{lee15a,
author = {Lee, Temple R. and De Wekker, Stephan F. J. and Pal, Sandip and Andrews, Arlyn E. and Kofler, Jonathan},
title = {Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2015},
volume = {67},
doi = {10.3402/tellusb.v67.25659}
}
|
| Lee S, Kim D, Im J, Lee M-I and Park Y-G ({2017}), "CO2 concentration and its spatiotemporal variation in the troposphere using multi-sensor satellite data, carbon tracker, and aircraft observations", GISCIENCE & REMOTE SENSING. Vol. {54}({4}), pp. 592-613. |
| Abstract: Satellite-based atmospheric CO2 observations have provided a great opportunity to improve our understanding of the global carbon cycle. However, thermal infrared (TIR)-based satellite observations, which are useful for the investigation of vertical distribution and the transport of CO2, have not yet been studied as much as the column amount products derived from shortwave infrared data. In this study, TIR-based satellite CO2 products - from Atmospheric Infrared Sounder, Tropospheric Emission Spectrometer (TES), and Thermal And Near infrared Sensor for carbon Observation - and carbon tracker mole fraction data were compared with in situ Comprehensive Observation Network for Trace gases by AIrLiner (CONTRAIL) data for different locations. The TES CO2 product showed the best agreement with CONTRAIL CO2 data resulting in R-2 similar to 0.87 and root-mean-square error similar to 0.9. The vertical distribution of CO2 derived by TES strongly depends on the geophysical characteristics of an area. Two different climate regions (i.e., southeastern Japan and southeastern Australia) were examined in terms of the vertical distribution and transport of CO2. Results show that while vertical distribution of CO2 around southeastern Japan was mainly controlled by horizontal and vertical winds, horizontal wind might be a major factor to control the CO2 transport around southeastern Australia. In addition, the vertical transport of CO2 also varies by region, which is mainly controlled by anthropogenic CO2, and horizontal and omega winds. This study improves our understanding of vertical distribution and the transport of CO2, both of which vary by region, using TIR-based satellite CO2 observations and meteorological variables. |
BibTeX:
@article{lee17a,
author = {Lee, Sanggyun and Kim, Dongmin and Im, Jungho and Lee, Myong-In and Park, Young-Gyu},
title = {CO2 concentration and its spatiotemporal variation in the troposphere using multi-sensor satellite data, carbon tracker, and aircraft observations},
journal = {GISCIENCE & REMOTE SENSING},
year = {2017},
volume = {54},
number = {4},
pages = {592--613},
doi = {10.1080/15481603.2017.1317120}
}
|
| Lee TR, De Wekker SFJ and Pal S ({2018}), "The Impact of the Afternoon Planetary Boundary-Layer Height on the Diurnal Cycle of CO and Mixing Ratios at a Low-Altitude Mountaintop", BOUNDARY-LAYER METEOROLOGY., JUL, {2018}. Vol. {168}({1}), pp. {81-102}. |
| Abstract: Mountaintop trace-gas mixing ratios are often assumed to represent free atmospheric values, but are affected by valley planetary boundary-layer (PBL) air at certain times. We hypothesize that the afternoon valley-PBL height relative to the ridgetop is important in the diurnal cycle of mountaintop trace-gas mixing ratios. To investigate this, we use, (1) 4-years (1 January 2009-31 December 2012) of CO and mixing-ratio measurements and supporting meteorological observations from Pinnacles (, , 1017 m a.s.l.), which is a monitoring site in the Appalachian Mountains, (2) regional mixing-ratio measurements, and (3) PBL heights determined from a nearby sounding station. Results reveal that the amplitudes of the diurnal cycles of CO and mixing ratios vary as a function of the daytime maximum valley-PBL height relative to the ridgetop. The mean diurnal cycle for the subset of days when the afternoon valley-PBL height is at least 400 m below the ridgetop shows a daytime CO mixing-ratio increase, implying the transport of PBL air from the valley to the mountaintop. During the daytime, on days when the PBL heights exceed the mountaintop, PBL dilution and entrainment cause CO mixing ratios to decrease. This decrease in CO mixing ratio, especially on days when PBL heights are at least 400 m above the ridgetop, suggests that measurements from these days can be used as with afternoon measurements from flat terrain in applications requiring regionally-representative measurements. |
BibTeX:
@article{lee18a,
author = {Lee, Temple R. and De Wekker, Stephan F. J. and Pal, Sandip},
title = {The Impact of the Afternoon Planetary Boundary-Layer Height on the Diurnal Cycle of CO and Mixing Ratios at a Low-Altitude Mountaintop},
journal = {BOUNDARY-LAYER METEOROLOGY},
year = {2018},
volume = {168},
number = {1},
pages = {81-102},
doi = {{10.1007/s10546-018-0343-9}}
}
|
| Lefrançois E (2009), "Revegetation and reclamation of oil sands process-affected material using Frankia-inoculated alders: Field and greenhouse trials". Thesis at: McGill University. |
BibTeX:
@mastersthesis{lefrancois09a,
author = {Lefrançois, Elisabeth},
title = {Revegetation and reclamation of oil sands process-affected material using Frankia-inoculated alders: Field and greenhouse trials},
school = {McGill University},
year = {2009},
url = {http://digitool.library.mcgill.ca/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&forebear_coll=&user=GUEST&pds_handle=&pid=66758&con_lng=ENG&search_terms=&divType=&adjacency=N&rd_session=http://digitool.Library.McGill.CA:80/R/FT8AIQ9EGIVNJ1RIEL1L3JBY3VJSPXGBFKD2RGI227CGSACT1A-00024}
}
|
| Lenton A, Tilbrook B, Law RM, Bakker D, Doney SC, Gruber N, Ishii M, Hoppema M, Lovenduski NS, Matear RJ, McNeil BI, Metzl N, Fletcher SEM, Monteiro PMS, Roedenbeck C, Sweeney C and Takahashi T ({2013}), "Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009", BIOGEOSCIENCES. Vol. {10}({6}), pp. 4037-4054. |
| Abstract: The Southern Ocean (44-75 degrees S) plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled ocean regions. Different approaches have been used to estimate sea-air CO2 fluxes in this region: synthesis of surface ocean observations, ocean biogeochemical models, and atmospheric and ocean inversions. As part of the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we combine these different approaches to quantify and assess the magnitude and variability in Southern Ocean sea-air CO2 fluxes between 1990-2009. Using all models and inversions (26), the integrated median annual sea-air CO2 flux of -0.42+/-0.07 Pg C yr(-1) for the 44-75 degrees S region, is consistent with the -0.27+/-0.13 Pg C yr(-1) calculated using surface observations. The circumpolar region south of 58 degrees S has a small net annual flux (model and inversion median: -0.04+/-0.07 Pg C yr(-1) and observations: +0.04+/-0.02 Pg C yr(-1)), with most of the net annual flux located in the 44 to 58 degrees S circumpolar band (model and inversion median: -0.36+/-0.09 Pg C yr(-1) and observations: -0.35+/-0.09 Pg C yr(-1)). Seasonally, in the 44-58 degrees S region, the median of 5 ocean biogeochemical models captures the observed sea-air CO2 flux seasonal cycle, while the median of 11 atmospheric inversions shows little seasonal change in the net flux. South of 58 degrees S, neither atmospheric inversions nor ocean biogeochemical models reproduce the phase and amplitude of the observed seasonal sea-air CO2 flux, particularly in the Austral Winter. Importantly, no individual atmospheric inversion or ocean biogeochemical model is capable of reproducing both the observed annual mean uptake and the observed seasonal cycle. This raises concerns about projecting future changes in Southern Ocean CO2 fluxes. The median interannual variability from atmospheric inversions and ocean biogeochemical models is substantial in the Southern Ocean; up to 25% of the annual mean flux, with 25% of this interannual variability attributed to the region south of 58 degrees S. Resolving long-term trends is difficult due to the large interannual variability and short time frame (1990-2009) of this study; this is particularly evident from the large spread in trends from inversions and ocean biogeochemical models. Nevertheless, in the period 1990-2009 ocean biogeochemical models do show increasing oceanic uptake consistent with the expected increase of -0.05 Pg C yr(-1) decade(-1). In contrast, atmospheric inversions suggest little change in the strength of the CO2 sink broadly consistent with the results of Le Quere et al. (2007). |
BibTeX:
@article{lenton13a,
author = {Lenton, A. and Tilbrook, B. and Law, R. M. and Bakker, D. and Doney, S. C. and Gruber, N. and Ishii, M. and Hoppema, M. and Lovenduski, N. S. and Matear, R. J. and McNeil, B. I. and Metzl, N. and Fletcher, S. E. Mikaloff and Monteiro, P. M. S. and Roedenbeck, C. and Sweeney, C. and Takahashi, T.},
title = {Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009},
journal = {BIOGEOSCIENCES},
year = {2013},
volume = {10},
number = {6},
pages = {4037--4054},
doi = {10.5194/bg-10-4037-2013}
}
|
| Levinson DH and Lawrimore JH ({2008}), "State of the climate in 2007", BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY., JUL, {2008}. Vol. {89}({7, S}), pp. {10+}. |
| Abstract: The combined land and ocean surface temperature in 2007 fell within the 10 highest on record while the average land temperature was the warmest since global records began in 1880. In the low to midtroposphere, the annual global mean temperature was among the five warmest since reliable global records began in 1958, but still cooler than the record warmest year of 1998. For the fourth consecutive year, the annual precipitation averaged over global land surfaces was above the long-term mean, although the anomaly was significantly less than in 2006 when the annual value was the eighth wettest since 1901. The globally averaged concentration of carbon dioxide (CO2) continued to increase in 2007, having risen to 382.7 ppm at the Mauna Loa Observatory in Hawaii. The average rate of rise of CO2 has been 1.6 ppm yr(-1) since 1980; however, since 2000 this has increased to 1.9 ppm yr(-1). In addition, both methane (CH4) and carbon monoxide (CO) concentrations were also higher in 2007. Over the oceans, global SST during 2007 showed significant departures from the 1971-2000 climatology. Annual average upper-ocean heat content anomalies declined between 2006 and 2007 in the eastern equatorial Pacific and increased in off-equatorial bands in that ocean basin. These changes were consistent with the transition from an El Nino in 2006 to a La Nina in 2007. The global mean see level anomaly (SLA) in 2007 was 1.1 mm higher than in 2006, which is about one standard deviation below what would be excepted from the 15-yr trend value of 3.4 mm yr(-1). In the tropics, the Atlantic hurricane season was near normal in 2007, although slightly more active than in 2006. In the north and south Indian Ocean Basins, both the seasonal totals and intensity of tropical cyclones (TC) were significantly above average, and included two Saffir-Simpson category 5 TCs in the north Indian Ocean and a world record rainfall amount of 5510 mm over a 3-8 day period on the island of Reunion in the south Indian Ocean. In the polar regions 2007 was the warmest on record for the Arctic, and continued a general, Arctic-wide warming trend that began in the mid-1960s. An unusually strong high pressure region in the Beaufort Sea during summer contributed to a record minimum Arctic sea ice cover in September. Measurements of the mass balance of glaciers and ice caps indicate that in most of the world, glaciers and ice caps indicate that in most of the world, glaciers are shrinking in mass. The Greenland ice sheet experienced records in both the duration and extent of the summer surface melt. From the continental scale as a whole the Antarctic was warmer than average in 2007, although the Antarctic Peninsula was considerably cooler than average. The size of the ozone hole was below the record levels of 2006, and near the average of the past 15 yr, due to warmer springtime temperatures in the Antarctic stratosphere. |
BibTeX:
@article{levinson08a,
author = {Levinson, D. H. and Lawrimore, J. H.},
title = {State of the climate in 2007},
journal = {BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY},
year = {2008},
volume = {89},
number = {7, S},
pages = {10+},
doi = {10.1175/BAMS-89-7-StateoftheClimate}
}
|
| Li C, Zhou L, Qin D, Liu L, Qin X, Wang Z and Ren J ({2014}), "Preliminary study of atmospheric carbon dioxide in a glacial area of the Qilian Mountains, west China", ATMOSPHERIC ENVIRONMENT., DEC, {2014}. Vol. {99}, pp. 485-490. |
| Abstract: Carbon dioxide represents the most important contribution to increased radiative forcing. The preliminary results of the atmospheric carbon dioxide mole fraction from the glacial region in the Qilian Mountains area, in the northeast of the Qinghai-Xizang (Tibetan) Plateau during July, 2009 to October, 2012 are presented. The annual mean CO2 mole fractions in 2010 and 2011 were 388.4 +/- 2.7 ppm and 392.7 +/- 2.6 ppm, respectively. These values were consistent with the CO2 mole fractions from the WMO/GAW stations located at high altitudes. However, both the concentration and seasonal variation were significantly lower than stations located adjacent to megacities or economic centers at low latitudes in eastern China. Shorter durations of photosynthesis of the alpine vegetation system that exceeded respiration were detected at the Qilian Mountains glacial area. The annual mean increase during the sampling period was 2.9 ppm yr(-1) and this value was higher than the global mean values. Anthropogenic activities in the cities adjacent to the Qilian Mountains may have important influences on the CO2 mole fractions, especially in summer, when north and north-north-west winds are typical. (C) 2014 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{li14a,
author = {Li, Chuanjin and Zhou, Lingxi and Qin, Dahe and Liu, Lixin and Qin, Xiang and Wang, Zebin and Ren, Jiawen},
title = {Preliminary study of atmospheric carbon dioxide in a glacial area of the Qilian Mountains, west China},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2014},
volume = {99},
pages = {485--490},
doi = {10.1016/j.atmosenv.2014.10.020}
}
|
| Li R, Zhang M, Chen L, Kou X and Skorokhod A ({2017}), "CMAQ simulation of atmospheric CO2 concentration in East Asia: Comparison with GOSAT observations and ground measurements", ATMOSPHERIC ENVIRONMENT., JUL, {2017}. Vol. {160}, pp. 176-185. |
| Abstract: Satellite observations are widely used in global CO2 assimilations, but their quality for use in regional assimilation systems has not yet been thoroughly determined. Validation of satellite observations and model simulations of CO2 is crucial for carbon flux inversions. In this study, we focus on evaluating the uncertainties of model simulations and satellite observations. The atmospheric CO2 distribution in East Asia during 2012 was simulated using a regional chemical transport model (RAMS-CMAQ) and compared with both CO2 column density (XCO2) from the Gases Observing SATellite (GOSAT) and CO2 concentrations from the World Data Centre for Greenhouse Gases (WDCGG). The results indicate that simulated XCO2 is generally lower than GOSAT XCO2 by 1.19 ppm on average, and their monthly differences vary from 0.05 to 2.84 ppm, with the corresponding correlation coefficients ranging between 0.1 and 0.67. CMAQ simulations are good to capture the CO2 variation as ground-based observations, and their correlation coefficients are from 0.62 to 0.93, but the average value of CMAQ simulation is 2.4 ppm higher than ground-based observation. Thus, we inferred that the GOSAT retrievals may overestimate XCO2, which is consistent with the validation of GOSAT XCO2 using Total Carbon Column Observing Network measurements. The near-surface CO2 concentration was obviously overestimated in GOSAT XCO2. Compared with the relatively small difference between CMAQ and GOSAT XCO2, the large difference in CO2 near surface or their vertical profiles indicates more improvements are needed to reduce the uncertainties in both satellite observations and model simulations. (C) 2017 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{li17a,
author = {Li, Rong and Zhang, Meigen and Chen, Liangfu and Kou, Xingxia and Skorokhod, Andrei},
title = {CMAQ simulation of atmospheric CO2 concentration in East Asia: Comparison with GOSAT observations and ground measurements},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2017},
volume = {160},
pages = {176--185},
doi = {10.1016/j.atmosenv.2017.03.056}
}
|
| Liang M-C, Mahata S, Laskar AH and Bhattacharya SK ({2017}), "Spatiotemporal Variability of Oxygen Isotope Anomaly in near Surface Air CO2 over Urban, Semi-Urban and Ocean Areas in and around Taiwan", AEROSOL AND AIR QUALITY RESEARCH., MAR, {2017}. Vol. {17}({3}), pp. 706-720. |
| Abstract: The most commonly used tracers to probe the atmospheric and biogeochemical cycles of CO2 are (OCO)-O-16-C-12-O-16, (OCO)-O-16-C-13-O-16, and (OCO)-O-16-C-12-O-18. Considering the number and diversity of sources and sinks affecting CO2, these tracers are not always sufficient to constrain the fluxes of CO2 between the atmosphere and biosphere/hydrosphere. In this context, (OCO)-O-16-C-12-O-17 species was introduced but has rarely been used due to difficulties associated with its accurate measurement in natural samples. This tracer, expressed as an abundance anomaly in O-17, defined by Delta O-17 = ln(1 + delta O-17) - 0.516 x ln(1 + delta O-18) can independently constrain the fluxes associated with the terrestrial processes. The advantage of utilizing Delta O-17 over delta O-18 alone lies on the sensitivity of the former to the rates of biogeochemical processes involving multiple water reservoirs with spatial and temporal isotopic heterogeneities. To employ all the three oxygen isotopes for estimating fluxes of CO2, sources and processes affecting their partitioning have to be identified and quantified. Here, we measured Delta O-17 values in near surface atmospheric CO2 from Taiwan in urban and semi-urban areas and over the South China Sea. Strong spatiotemporal variation was seen, with an average Delta O-17 value of 0.332% and a mean variation of 0.043br> (relative to V-SMOW; 1-sigma standard deviation for a total of 140 samples). The large variation reflects combinations of distinct air masses carrying CO2 from sources having different Delta O-17 values: negative from combustion emissions, positive from the stratosphere, and a positive water-CO2 equilibration value from isotope exchange with leaf/soil/ocean waters. We observed that the variation of the semi-urban Delta O-17 values is largely affected by local biogeochemistry and stratospheric intrusion with only minor influence from anthropogenic emissions. This is the first oxygen anomaly study for near surface CO2 covering diverse source characteristics and has enormous potential in air CO2 source identification and constraining the global carbon budget. |
BibTeX:
@article{liang17a,
author = {Liang, Mao-Chang and Mahata, Sasadhar and Laskar, Amzad H. and Bhattacharya, Sourendra K.},
title = {Spatiotemporal Variability of Oxygen Isotope Anomaly in near Surface Air CO2 over Urban, Semi-Urban and Ocean Areas in and around Taiwan},
journal = {AEROSOL AND AIR QUALITY RESEARCH},
year = {2017},
volume = {17},
number = {3},
pages = {706--720},
doi = {10.4209/aaqr.2016.04.0171}
}
|
| Lin JC, Mallia DV, Wu D and Stephens BB ({2017}), "How can mountaintop CO2 observations be used to constrain regional carbon fluxes?", ATMOSPHERIC CHEMISTRY AND PHYSICS., MAY 3, {2017}. Vol. {17}({9}), pp. 5561-5581. |
| Abstract: Despite the need for researchers to understand terrestrial biospheric carbon fluxes to account for carbon cycle feedbacks and predict future CO2 concentrations, knowledge of these fluxes at the regional scale remains poor. This is particularly true in mountainous areas, where complex meteorology and lack of observations lead to large uncertainties in carbon fluxes. Yet mountainous regions are often where significant forest cover and biomass are found - i.e., areas that have the potential to serve as carbon sinks. As CO2 observations are carried out in mountainous areas, it is imperative that they are properly interpreted to yield information about carbon fluxes. In this paper, we present CO2 observations at three sites in the mountains of the western US, along with atmospheric simulations that attempt to extract information about biospheric carbon fluxes from the CO2 observations, with emphasis on the observed and simulated diurnal cycles of CO2. We show that atmospheric models can systematically simulate the wrong diurnal cycle and significantly misinterpret the CO2 observations, due to erroneous atmospheric flows as a result of terrain that is misrepresented in the model. This problem depends on the selected vertical level in the model and is exacerbated as the spatial resolution is degraded, and our results indicate that a fine grid spacing of similar to 4 km or less may be needed to simulate a realistic diurnal cycle of CO2 for sites on top of the steep mountains examined here in the American Rockies. In the absence of higher resolution models, we recommend coarse-scale models to focus on assimilating afternoon CO2 observations on mountaintop sites over the continent to avoid misrepresentations of nocturnal transport and influence. |
BibTeX:
@article{lin17a,
author = {Lin, John C. and Mallia, Derek V. and Wu, Dien and Stephens, Britton B.},
title = {How can mountaintop CO2 observations be used to constrain regional carbon fluxes?},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {9},
pages = {5561--5581},
doi = {10.5194/acp-17-5561-2017}
}
|
| Lindqvist H, O'Dell CW, Basu S, Boesch H, Chevallier F, Deutscher N, Feng L, Fisher B, Hase F, Inoue M, Kivi R, Morino I, Palmer PI, Parker R, Schneider M, Sussmann R and Yoshida Y ({2015}), "Does GOSAT capture the true seasonal cycle of carbon dioxide?", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({22}), pp. 13023-13040. |
| Abstract: The seasonal cycle accounts for a dominant mode of total column CO2 (XCO2) annual variability and is connected to CO2 uptake and release; it thus represents an important quantity to test the accuracy of the measurements from space. We quantitatively evaluate the XCO2 seasonal cycle of the Greenhouse Gases Observing Satellite (GOSAT) observations from the Atmospheric CO2 Observations from Space (ACOS) retrieval system and compare average regional seasonal cycle features to those directly measured by the Total Carbon Column Observing Network (TCCON). We analyse the mean seasonal cycle amplitude, dates of maximum and minimum XCO2, as well as the regional growth rates in XCO2 through the fitted trend over several years. We find that GOSAT/ACOS captures the seasonal cycle amplitude within 1.0 ppm accuracy compared to TCCON, except in Europe, where the difference exceeds 1.0 ppm at two sites, and the amplitude captured by GOSAT/ACOS is generally shallower compared to TCCON. This bias over Europe is not as large for the other GOSAT retrieval algorithms (NIES v02.21, RemoTeC v2.35, UoL v5.1, and NIES PPDF-S v.02.11), al-though they have significant biases at other sites. We find that the ACOS bias correction partially explains the shallow amplitude over Europe. The impact of the co-location method and aerosol changes in the ACOS algorithm were also tested and found to be few tenths of a ppm and mostly non-systematic. We find generally good agreement in the date of minimum XCO2 between ACOS and TCCON, but ACOS generally infers a date of maximum XCO2 2-3 weeks later than TCCON. We further analyse the latitudinal dependence of the seasonal cycle amplitude throughout the Northern Hemisphere and compare the dependence to that predicted by current optimized models that assimilate in situ measurements of CO2. In the zonal averages, models are consistent with the GOSAT amplitude to within 1.4 ppm, depending on the model and latitude. We also show that the seasonal cycle of XCO2 depends on longitude especially at the mid-latitudes: the amplitude of GOSAT XCO2 doubles from western USA to East Asia at 45-50 degrees N, which is only partially shown by the models. In general, we find that model-to-model differences can be larger than GOSAT-to-model differences. These results suggest that GOSAT/ACOS retrievals of the XCO2 seasonal cycle may be sufficiently accurate to evaluate land surface models in regions with significant discrepancies between the models. |
BibTeX:
@article{lindqvist15a,
author = {Lindqvist, H. and O'Dell, C. W. and Basu, S. and Boesch, H. and Chevallier, F. and Deutscher, N. and Feng, L. and Fisher, B. and Hase, F. and Inoue, M. and Kivi, R. and Morino, I. and Palmer, P. I. and Parker, R. and Schneider, M. and Sussmann, R. and Yoshida, Y.},
title = {Does GOSAT capture the true seasonal cycle of carbon dioxide?},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2015},
volume = {15},
number = {22},
pages = {13023--13040},
doi = {10.5194/acp-15-13023-2015}
}
|
| Liu J, Fung I, Kalnay E, Kang J-S, Olsen ET and Chen L ({2012}), "Simultaneous assimilation of AIRS Xco(2) and meteorological observations in a carbon climate model with an ensemble Kalman filter", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 9, {2012}. Vol. {117} |
| Abstract: This study is our first step toward the generation of 6 hourly 3-D CO2 fields that can be used to validate CO2 forecast models by combining CO2 observations from multiple sources using ensemble Kalman filtering. We discuss a procedure to assimilate Atmospheric Infrared Sounder (AIRS) column-averaged dry-air mole fraction of CO2 (Xco(2)) in conjunction with meteorological observations with the coupled Local Ensemble Transform Kalman Filter (LETKF)-Community Atmospheric Model version 3.5. We examine the impact of assimilating AIRS Xco(2) observations on CO2 fields by comparing the results from the AIRS-run, which assimilates both AIRS Xco(2) and meteorological observations, to those from the meteor-run, which only assimilates meteorological observations. We find that assimilating AIRS Xco(2) results in a surface CO2 seasonal cycle and the N-S surface gradient closer to the observations. When taking account of the CO2 uncertainty estimation from the LETKF, the CO2 analysis brackets the observed seasonal cycle. Verification against independent aircraft observations shows that assimilating AIRS Xco(2) improves the accuracy of the CO2 vertical profiles by about 0.5-2 ppm depending on location and altitude. The results show that the CO2 analysis ensemble spread at AIRS Xco(2) space is between 0.5 and 2 ppm, and the CO2 analysis ensemble spread around the peak level of the averaging kernels is between 1 and 2 ppm. This uncertainty estimation is consistent with the magnitude of the CO2 analysis error verified against AIRS Xco(2) observations and the independent aircraft CO2 vertical profiles. |
BibTeX:
@article{liu12a,
author = {Liu, Junjie and Fung, Inez and Kalnay, Eugenia and Kang, Ji-Sun and Olsen, Edward T. and Chen, Luke},
title = {Simultaneous assimilation of AIRS Xco(2) and meteorological observations in a carbon climate model with an ensemble Kalman filter},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2012},
volume = {117},
doi = {10.1029/2011JD016642}
}
|
| Liu Z, Bambha RP, Pinto JP, Zeng T, Boylan J, Huang M, Lei H, Zhao C, Liu S, Mao J, Schwalm CR, Shi X, Wei Y and Michelsen HA ({2014}), "Toward verifying fossil fuel CO2 emissions with the CMAQ model: Motivation, model description and initial simulation", JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION., APR 3, {2014}. Vol. {64}({4}), pp. 419-435. |
| Abstract: Motivated by the question of whether and how a state-of-the-art regional chemical transport model (CTM) can facilitate characterization of CO2 spatiotemporal variability and verify CO2 fossil-fuel emissions, we for the first time applied the Community Multiscale Air Quality (CMAQ) model to simulate CO2. This paper presents methods, input data, and initial results for CO2 simulation using CMAQ over the contiguous United States in October 2007. Modeling experiments have been performed to understand the roles of fossil-fuel emissions, biosphere-atmosphere exchange, and meteorology in regulating the spatial distribution of CO2 near the surface over the contiguous United States. Three sets of net ecosystem exchange (NEE) fluxes were used as input to assess the impact of uncertainty of NEE on CO2 concentrations simulated by CMAQ. Observational data from six tall tower sites across the country were used to evaluate model performance. In particular, at the Boulder Atmospheric Observatory (BAO), a tall tower site that receives urban emissions from Denver, CO, the CMAQ model using hourly varying, high-resolution CO2 fossil-fuel emissions from the Vulcan inventory and CarbonTracker optimized NEE reproduced the observed diurnal profile of CO2 reasonably well but with a low bias in the early morning. The spatial distribution of CO2 was found to correlate with NOx, SO2, and CO, because of their similar fossil-fuel emission sources and common transport processes. These initial results from CMAQ demonstrate the potential of using a regional CTM to help interpret CO2 observations and understand CO2 variability in space and time. The ability to simulate a full suite of air pollutants in CMAQ will also facilitate investigations of their use as tracers for CO2 source attribution. This work serves as a proof of concept and the foundation for more comprehensive examinations of CO2 spatiotemporal variability and various uncertainties in the future. Implications: Atmospheric CO2 has long been modeled and studied on continental to global scales to understand the global carbon cycle. This work demonstrates the potential of modeling and studying CO2 variability at fine spatiotemporal scales with CMAQ, which has been applied extensively, to study traditionally regulated air pollutants. The abundant observational records of these air pollutants and successful experience in studying and reducing their emissions may be useful for verifying CO2 emissions. Although there remains much more to further investigate, this work opens up a discussion on whether and how to study CO2 as an air pollutant. |
BibTeX:
@article{liu14a,
author = {Liu, Zhen and Bambha, Ray P. and Pinto, Joseph P. and Zeng, Tao and Boylan, Jim and Huang, Maoyi and Lei, Huimin and Zhao, Chun and Liu, Shishi and Mao, Jiafu and Schwalm, Christopher R. and Shi, Xiaoying and Wei, Yaxing and Michelsen, Hope A.},
title = {Toward verifying fossil fuel CO2 emissions with the CMAQ model: Motivation, model description and initial simulation},
journal = {JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION},
year = {2014},
volume = {64},
number = {4},
pages = {419--435},
doi = {10.1080/10962247.2013.816642}
}
|
| Liu S, Zhuang Q, He Y, Noormets A, Chen J and Gu L ({2016}), "Evaluating atmospheric CO2 effects on gross primary productivity and net ecosystem exchanges of terrestrial ecosystems in the conterminous United States using the AmeriFlux data and an artificial neural network approach", AGRICULTURAL AND FOREST METEOROLOGY., APR 15, {2016}. Vol. {220}, pp. 38-49. |
| Abstract: Quantitative understanding of regional gross primary productivity (GPP) and net ecosystem exchanges (NEE) and their responses to environmental changes are critical to quantifying the feedbacks of ecosystems to the global climate system. Numerous studies have used the eddy flux data to upscale the eddy covariance derived carbon fluxes from stand scales to regional and global scales. However, few studies incorporated atmospheric carbon dioxide (CO2) concentrations into those extrapolations. Here, we consider the effect of atmospheric CO2 using an artificial neural network (ANN) approach to upscale the AmeriFlux tower of NEE and the derived GPP to the conterminous United States. Two ANN models incorporating remote sensing variables at an 8-day time step were developed. One included CO2 as an explanatory variable and the other did not. The models were first trained, validated using eddy flux data, and then extrapolated to the region at a 0.05 degrees x 0.05 degrees (latitude x longitude) resolution from 2001 to 2006. We found that both models performed well in simulating site-level carbon fluxes. The spatially averaged annual GPP with and without considering the atmospheric CO2 were 789 and 788 g Cm-2 yr(-1), respectively (for NEE, the values were 112 and 109 g Cm-2 yr(-1), respectively). Model predictions were comparable with previous published results and MODIS GPP products. However, the difference in GPP between the two models exhibited a great spatial and seasonal variability, with an annual difference of 200 g Cm-2 yr(-1). Further analysis suggested that air temperature played an important role in determining the atmospheric CO2 effects on carbon fluxes. In addition, the simulation that did not consider atmospheric CO2 failed to detect ecosystem responses to droughts in part of the US in 2006. The study suggests that the spatially and temporally varied atmospheric CO2 concentrations should be factored into carbon quantification when scaling eddy flux data to a region. (C) 2016 Elsevier B.V. All rights reserved. |
BibTeX:
@article{liu16a,
author = {Liu, Shaoqing and Zhuang, Qianlai and He, Yujie and Noormets, Asko and Chen, Jiquan and Gu, Lianhong},
title = {Evaluating atmospheric CO2 effects on gross primary productivity and net ecosystem exchanges of terrestrial ecosystems in the conterminous United States using the AmeriFlux data and an artificial neural network approach},
journal = {AGRICULTURAL AND FOREST METEOROLOGY},
year = {2016},
volume = {220},
pages = {38--49},
doi = {10.1016/j.agrformet.2016.01.007}
}
|
| Liu M, Lei L, Liu D and Zeng Z-C ({2016}), "Geostatistical Analysis of CH4 Columns over Monsoon Asia Using Five Years of GOSAT Observations", REMOTE SENSING., MAY, {2016}. Vol. {8}({5}) |
| Abstract: The aim of this study is to evaluate the Greenhouse gases Observation SATellite (GOSAT) column-averaged CH4 dry air mole fraction (XCH4) data by using geostatistical analysis and conducting comparisons with model simulations and surface emissions. Firstly, we propose the use of a data-driven mapping approach based on spatio-temporal geostatistics to generate a regular and gridded mapping dataset of XCH4 over Monsoon Asia using five years of XCH4 retrievals by GOSAT from June 2009 to May 2014. The prediction accuracy of the mapping approach is assessed by using cross-validation, which results in a significantly high correlation of 0.91 and a small mean absolute prediction error of 8.77 ppb between the observed dataset and the prediction dataset. Secondly, with the mapping data, we investigate the spatial and temporal variations of XCH4 over Monsoon Asia and compare the results with previous studies on ground and other satellite observations. Thirdly, we compare the mapping XCH4 with model simulations from CarbonTracker-CH4 and find their spatial patterns very consistent, but GOSAT observations are more able to capture the local variability of XCH4. Finally, by correlating the mapping data with surface emission inventory, we find the geographical distribution of high CH4 values correspond well with strong emissions as indicated in the inventory map. Over the five-year period, the two datasets show a significant high correlation coefficient (0.80), indicating the dominant role of surface emissions in determining the distribution of XCH4 concentration in this region and suggesting a promising statistical way of constraining surface CH4 sources and sinks, which is simple and easy to implement using satellite observations over a long term period. |
BibTeX:
@article{liu16b,
author = {Liu, Min and Lei, Liping and Liu, Da and Zeng, Zhao-Cheng},
title = {Geostatistical Analysis of CH4 Columns over Monsoon Asia Using Five Years of GOSAT Observations},
journal = {REMOTE SENSING},
year = {2016},
volume = {8},
number = {5},
doi = {10.3390/rs8050361}
}
|
| Liu J, Bowman KW and Lee M ({2016}), "Comparison between the Local Ensemble Transform Kalman Filter (LETKF) and 4D-Var in atmospheric CO2 flux inversion with the Goddard Earth Observing System-Chem model and the observation impact diagnostics from the LETKF", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 16, {2016}. Vol. {121}({21}), pp. 13066-13087. |
BibTeX:
@article{liu16c,
author = {Liu, Junjie and Bowman, Kevin W. and Lee, Meemong},
title = {Comparison between the Local Ensemble Transform Kalman Filter (LETKF) and 4D-Var in atmospheric CO2 flux inversion with the Goddard Earth Observing System-Chem model and the observation impact diagnostics from the LETKF},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2016},
volume = {121},
number = {21},
pages = {13066--13087},
doi = {10.1002/2016JD025100}
}
|
| Liu S (2016), "Quantifying terrestrial ecosystem carbon dynamics with mechanistically-based biogeochemistry models and in situ and remotely sensed data". Thesis at: Purdue University. |
BibTeX:
@phdthesis{liu16d,
author = {Liu, Shaoqing},
title = {Quantifying terrestrial ecosystem carbon dynamics with mechanistically-based biogeochemistry models and in situ and remotely sensed data},
school = {Purdue University},
year = {2016},
url = {http://search.proquest.com/openview/6c838317951d8ea5b5e0409c75ea25e9/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Liu S, Zhuang Q, Chen M and Gu L (2016), "Quantifying spatially and temporally explicit CO2 fertilization effects on global terrestrial ecosystem carbon dynamics", Ecosphere. Vol. 7(7) |
BibTeX:
@article{liu16e,
author = {Liu, Shaoqing and Zhuang, Qianlai and Chen, Min and Gu, Lianhong},
title = {Quantifying spatially and temporally explicit CO2 fertilization effects on global terrestrial ecosystem carbon dynamics},
journal = {Ecosphere},
year = {2016},
volume = {7},
number = {7},
doi = {10.1002/ecs2.1391/full}
}
|
| Liu Z, Ballantyne AP, Poulter B, Anderegg WRL, Li W, Bastos A and Ciais P ({2018}), "Precipitation thresholds regulate net carbon exchange at the continental scale", NATURE COMMUNICATIONS., SEP 5, {2018}. Vol. {9} |
| Abstract: Understanding the sensitivity of ecosystem production and respiration to climate change is critical for predicting terrestrial carbon dynamics. Here we show that the primary control on the inter-annual variability of net ecosystem carbon exchange switches from production to respiration at a precipitation threshold between 750 and 950 mm yr(-1) in the contiguous United States. This precipitation threshold is evident across multiple datasets and scales of observation indicating that it is a robust result and provides a new scaling relationship between climate and carbon dynamics. However, this empirical precipitation threshold is not captured by dynamic global vegetation models, which tend to overestimate the sensitivity of production and underestimate the sensitivity of respiration to water availability in more mesic regions. Our results suggest that the short-term carbon balance of ecosystems may be more sensitive to respiration losses than previously thought and that model simulations may underestimate the positive carbon-climate feedbacks associated with respiration. |
BibTeX:
@article{liu18a,
author = {Liu, Zhihua and Ballantyne, Ashley P. and Poulter, Benjamin and Anderegg, William R. L. and Li, Wei and Bastos, Ana and Ciais, Philippe},
title = {Precipitation thresholds regulate net carbon exchange at the continental scale},
journal = {NATURE COMMUNICATIONS},
year = {2018},
volume = {9},
doi = {{10.1038/s41467-018-05948-1}}
}
|
| Liu J, Bowman K, Parazoo NC, Bloom AA, Wunch D, Jiang Z, Gurney KR and Schimel D ({2018}), "Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations", ENVIRONMENTAL RESEARCH LETTERS., SEP, {2018}. Vol. {13}({9}) |
| Abstract: With projections of increasing drought in the future, understanding how the natural carbon cycle responds to drought events is needed to predict the fate of the land carbon sink and future atmospheric CO2 concentrations and climate. We quantified the impacts of the 2011 and 2012 droughts on terrestrial ecosystem carbon uptake anomalies over the contiguous US (CONUS) relative to non-drought years during 2010-2015 using satellite observations and the carbon monitoring system-flux inversion modeling framework. Soilmoisture and temperature anomalies are good predictors of gross primary production anomalies (R-2 > 0.6) in summer but less so for net biosphere production (NBP) anomalies, reflecting different respiration responses. We showed that regional responses combine in complicated ways to produce the observed CONUS responses. Because of the compensating effect of the carbonflux anomalies between northern and southern CONUS in 2011 and between spring and summer in 2012, the annual NBP decreased by 0.10 +/- 0.16 GtC in 2011, and increased by 0.10 +/- 0.16 GtC in 2012 over CONUS, consistent with previous reported results. Over the 2011 and 2012 drought-impacted regions, the reductions in NBP were similar to 40% of the regional annual fossil fuel emissions, underscoring the importance of quantifying natural carbon flux variability as part of an overall observing strategy. The NBP reductions over the 2011 and 2012 CONUS drought-impacted region were opposite to the global atmospheric CO2 growth rate anomaly, implying that global atmospheric CO2 growth rate is an offsetting effect between enhanced uptake and emission, and enhancing the understanding of regional carbon-cycle climate relationship is necessary to improve the projections of future climate. |
BibTeX:
@article{liu18b,
author = {Liu, Junjie and Bowman, Kevin and Parazoo, Nicholas C. and Bloom, A. Anthony and Wunch, Debra and Jiang, Zhe and Gurney, Kevin R. and Schimel, Dave},
title = {Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations},
journal = {ENVIRONMENTAL RESEARCH LETTERS},
year = {2018},
volume = {13},
number = {9},
doi = {{10.1088/1748-9326/aad5ef}}
}
|
| Liu Y, Yue T, Zhang L, Zhao N, Zhao M and Liu Y ({2018}), "Simulation and analysis of XCO2 in North China based on high accuracy surface modeling", ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH., SEP, {2018}. Vol. {25}({27, SI}), pp. {27378-27392}. |
| Abstract: As an important cause of global warming, CO2 concentrations and their changes have aroused worldwide concern. Establishing explicit understanding of the spatial and temporal distributions of CO2 concentrations at regional scale is a crucial technical problem for climate change research. High accuracy surface modeling (HASM) is employed in this paper using the output of the CO2 concentrations from weather research and forecasting-chemistry (WRF-CHEM) as the driving fields, and the greenhouse gases observing satellite (GOSAT) retrieval XCO2 data as the accuracy control conditions to obtain high accuracy XCO2 fields. WRF-CHEM is an atmospheric chemical transport model designed for regional studies of CO2 concentrations. Verified by ground- and space-based observations, WRF-CHEM has a limited ability to simulate the conditions of CO2 concentrations. After conducting HASM, we obtain a higher accuracy distribution of the CO2 in North China than those calculated using the classical Kriging and inverse distance weighted (IDW) interpolation methods, which were often used in past studies. The cross-validation also shows that the averaging mean absolute error (MAE) of the results from HASM is 1.12 ppmv, and the averaging root mean square error (RMSE) is 1.41 ppmv, both of which are lower than those of the Kriging and IDW methods. This study also analyses the space-time distributions and variations of the XCO2 from the HASM results. This analysis shows that in February and March, there was the high value zone in the southern region of study area relating to heating in the winter and the dense population. The XCO2 concentration decreased by the end of the heating period and during the growing period of April and May, and only some relatively high value zones continued to exist. |
BibTeX:
@article{liu18c,
author = {Liu, Yu and Yue, Tianxiang and Zhang, Lili and Zhao, Na and Zhao, Miaomiao and Liu, Yi},
title = {Simulation and analysis of XCO2 in North China based on high accuracy surface modeling},
journal = {ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH},
year = {2018},
volume = {25},
number = {27, SI},
pages = {27378-27392},
doi = {{10.1007/s11356-018-2683-x}}
}
|
| Lokupitiya RS, Zupanski D, Denning AS, Kawa SR, Gurney KR and Zupanski M ({2008}), "Estimation of global CO2 fluxes at regional scale using the maximum likelihood ensemble filter", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 22, {2008}. Vol. {113}({D20}) |
| Abstract: We use an ensemble-based data assimilation method, known as the maximum likelihood ensemble filter (MLEF), which has been coupled with a global atmospheric transport model to estimate slowly varying biases of carbon surface fluxes. Carbon fluxes for this test consist of hourly gross primary production and ecosystem, respiration over land, and air-sea gas exchange. Persistent multiplicative biases intended to represent incorrectly simulated biogeochemical or land-management processes such as stand age, soil fertility, or coarse woody debris were estimated for 1 year at 10 degrees longitude by 6 degrees latitude spatial resolution and with an 8-week time window. We tested the model using a pseudodata experiment with an existing observation network that includes flasks, aircraft profiles, and continuous measurements. Because of the underconstrained nature of the problem, strong covariance smoothing was applied in the first data assimilation cycle, and localization schemes have been introduced. Error covariance was propagated in subsequent cycles. The coupled model satisfactorily recovered the land biases in densely observed areas. Ocean biases, however, were poorly constrained by the atmospheric observations. Unlike in batch mode inversions, the MLEF has a capability of assimilating large observation vectors and hence is suitable for assimilating hourly continuous observations and satellite observations in the future. Uncertainty was reduced further in our pseudodata experiment than by previous batch methods because of the ability to assimilate a large observation vector. Propagation of spatial covariance and dynamic localization avoid the need for prescribed spatial patterns of error covariance centered at observation sites as in previous grid-scale methods. |
BibTeX:
@article{lokupitiya08a,
author = {Lokupitiya, R. S. and Zupanski, D. and Denning, A. S. and Kawa, S. R. and Gurney, K. R. and Zupanski, M.},
title = {Estimation of global CO2 fluxes at regional scale using the maximum likelihood ensemble filter},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2008},
volume = {113},
number = {D20},
doi = {10.1029/2007JD009679}
}
|
| Luan T, LingXi Z, ShuangXi F, Yao B, Wang H and Liu Z (2014), "Atmospheric CO2 Data Filtering Method and Characteristics of the Molar Fractions at the Longfengshan WMO/GAW Regional Station in China", Environmental Science. Vol. 35(8) |
BibTeX:
@article{luan14a,
author = {Luan, Tian and Zhou LingXi and Fang ShuangXi and Yao, Bo and Wang, Hongyang and Liu, Zhao},
title = {Atmospheric CO2 Data Filtering Method and Characteristics of the Molar Fractions at the Longfengshan WMO/GAW Regional Station in China},
journal = {Environmental Science},
year = {2014},
volume = {35},
number = {8},
url = {http://www.hjkx.ac.cn/hjkx/ch/html/20140804.htm}
}
|
| Lukyanov AN, Gan'shin AV, Zhuravlev RV, Maksyutov SS and Varlagin AV ({2015}), "Global Lagrangian Atmospheric Dispersion Model", IZVESTIYA ATMOSPHERIC AND OCEANIC PHYSICS., SEP, {2015}. Vol. {51}({5}), pp. 505-511. |
| Abstract: The Global Lagrangian Atmospheric Dispersion Model (GLADIM) is described. GLADIM is based on the global trajectory model, which had been developed earlier and uses fields of weather parameters from different atmospheric reanalysis centers for calculations of trajectories of air mass that include trace gases. GLADIM includes the parameterization of turbulent diffusion and allows the forward calculation of concentrations of atmospheric tracers at nodes of a global regular grid when a source is specified. Thus, GLADIM can be used for the forward simulation of pollutant propagation (volcanic ash, radionuclides, and so on). Working in the reverse direction, GLADIM allows the detection of remote sources that mainly contribute to the tracer concentration at an observation point. This property of Lagrangian models is widely used for data analysis and the reverse modeling of emission sources of a pollutant specified. In this work we describe the model and some results of its validation through a comparison with results of a similar model and observation data. |
BibTeX:
@article{lukyanov15a,
author = {Lukyanov, A. N. and Gan'shin, A. V. and Zhuravlev, R. V. and Maksyutov, Sh. Sh. and Varlagin, A. V.},
title = {Global Lagrangian Atmospheric Dispersion Model},
journal = {IZVESTIYA ATMOSPHERIC AND OCEANIC PHYSICS},
year = {2015},
volume = {51},
number = {5},
pages = {505--511},
doi = {10.1134/S0001433815040076}
}
|
| Luus KA and Lin JC ({2015}), "The Polar Vegetation Photosynthesis and Respiration Model: a parsimonious, satellite-data-driven model of high-latitude CO2 exchange", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {8}({8}), pp. 2655-2674. |
| Abstract: We introduce the Polar Vegetation Photosynthesis and Respiration Model (PolarVPRM), a remote-sensing-based approach for generating accurate, high-resolution (>= 1 km(2), 3 hourly) estimates of net ecosystem CO2 exchange (NEE). PolarVPRM simulates NEE using polar-specific vegetation classes, and by representing high-latitude influences on NEE, such as the influence of soil temperature on subnivean respiration. We present a description, validation and error analysis (first-order Taylor expansion) of PolarVPRM, followed by an examination of per-pixel trends (2001-2012) in model output for the North American terrestrial region north of 55 degrees N. PolarVPRM was validated against eddy covariance (EC) observations from nine North American sites, of which three were used in model calibration. Comparisons of EC NEE to NEE from three models indicated that PolarVPRM displayed similar or better statistical agreement with eddy covariance observations than existing models showed. Trend analysis (2001-2012) indicated that warming air temperatures and drought stress in forests increased growing season rates of respiration, and decreased rates of net carbon uptake by vegetation when air temperatures exceeded optimal temperatures for photosynthesis. Concurrent increases in growing season length at Arctic tundra sites allowed for increases in photosynthetic uptake over time by tundra vegetation. PolarVPRM estimated that the North American high-latitude region changed from a carbon source (2001-2004) to a carbon sink (2005-2010) to again a source (2011-2012) in response to changing environmental conditions. |
BibTeX:
@article{luus15a,
author = {Luus, K. A. and Lin, J. C.},
title = {The Polar Vegetation Photosynthesis and Respiration Model: a parsimonious, satellite-data-driven model of high-latitude CO2 exchange},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2015},
volume = {8},
number = {8},
pages = {2655--2674},
doi = {10.5194/gmd-8-2655-2015}
}
|
| Mabuchi K, Takagi H and Maksyutov S ({2016}), "Relationships between CO2 Flux Estimated by Inverse Analysis and Land Surface Elements in South America and Africa", JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN. Vol. {94}({5}), pp. 415-430. |
| Abstract: Inverse analysis estimates the regional flux of greenhouse gases between the earth's surface and atmosphere using observed atmospheric concentration data that include satellite data. In particular, this method is effective in estimating the flux in regions where observational flux data are limited. However, inverse analysis is basically a mathematical optimization method. Therefore, confirmation of the causal validity of the spatial and temporal changes in the estimated flux is necessary. One confirmation method is validation of the relationship with physical and biological observation data (analysis data) of confirmed accuracy. In this study, the features and validity of changes in the carbon dioxide (CO2) flux estimated by inverse analysis were verified via interrelation analysis, with changes in precipitation, short-wave radiation, surface temperature, and Normalized Difference Vegetation Index (NDVI) in regions of South America and Africa where CO2 flux observation data are limited. Sufficient accuracy of the land surface elements is required for the analysis results to confirm the CO2 flux estimated by inverse analysis. An examination of the correlation of anomalies showed consistent relationships among the precipitation, short-wave radiation, surface temperature, and NDVI data used in this study, which were independently created. The relationships between change in the estimated CO2 flux and characteristic changes in the land surface elements in South America and Africa were consistent for each region. This study confirmed the physical and biological validity of the changes in the CO2 flux estimated by inverse analysis. During the period of this study, the NDVI anomaly was influential in South America and the precipitation (soil wetness) anomaly was an essential factor in Africa for the CO2 flux anomaly. The short-wave radiation anomaly was also influential in both South America and Africa. The distinctive relationships are more clearly detected in the results of inverse analysis using both ground-based CO2 concentration data and the Greenhouse gases Observing SATellite (GOSAT) data than in the results using only ground-based CO2 concentration data. This demonstrates the usefulness of GOSAT data in regions with limited atmospheric CO2 concentration data. |
BibTeX:
@article{mabuchi16a,
author = {Mabuchi, Kazuo and Takagi, Hiroshi and Maksyutov, Shamil},
title = {Relationships between CO2 Flux Estimated by Inverse Analysis and Land Surface Elements in South America and Africa},
journal = {JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN},
year = {2016},
volume = {94},
number = {5},
pages = {415--430},
doi = {10.2151/jmsj.2016-021}
}
|
| Macatangay R, Warneke T, Gerbig C, Koerner S, Ahmadov R, Heimann M and Notholt J ({2008}), "A framework for comparing remotely sensed and in-situ CO2 concentrations", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {8}({9}), pp. 2555-2568. |
| Abstract: A framework has been developed that allows validating CO2 column averaged volume mixing ratios (VMRs) retrieved from ground-based solar absorption measurements using Fourier transform infrared spectrometry (FTS) against measurements made in-situ (such as from aircrafts and tall towers). Since in-situ measurements are done frequently and at high accuracy on the global calibration scale, linking this scale with FTS total column retrievals ultimately provides a calibration scale for remote sensing. FTS, tower and aircraft data were analyzed from measurements during the CarboEurope Regional Experiment Strategy (CERES) from May to June 2005 in Biscarrosse, France. Carbon dioxide VMRs from the MetAir Dimona aircraft, the TM3 global transport model and Observations of the Middle Stratosphere (OMS) balloon based experiments were combined and integrated to compare with the FTS measurements. The comparison allows for calibrating the retrieved carbon dioxide VMRs from the FTS. The Stochastic Time Inverted Lagrangian Transport (STILT) model was then utilized to identify differences in surface influence regions or footprints between the FTS and the aircraft CO2 concentrations. Additionally, the STILT model was used to compare carbon dioxide concentrations from a tall tower situated in close proximity to the FTS station. The STILT model was then modified to produce column concentrations of CO2 to facilitate comparison with the FTS data. These comparisons were additionally verified by using the Weather Research and Forecasting -; Vegetation Photosynthesis and Respiration Model (WRF-VPRM). The differences between the model-tower and the model-FTS were then used to calculate an effective bias of approximately -2.5 ppm between the FTS and the tower. This bias is attributed to the scaling factor used in the FTS CO2 data, which was to a large extent derived from the aircraft measurements made within a 50 km distance from the FTS station: spatial heterogeneity of carbon dioxide in the coastal area caused a low bias in the FTS calibration. Using STILT for comparing remotely sensed CO2 data with tower measurements of carbon dioxide and quantifying this comparison by means of an effective bias, provided a framework or a `transfer standard' that allowed validating the FTS retrievals versus measurements made in-situ. |
BibTeX:
@article{macatangay08a,
author = {Macatangay, R. and Warneke, T. and Gerbig, C. and Koerner, S. and Ahmadov, R. and Heimann, M. and Notholt, J.},
title = {A framework for comparing remotely sensed and in-situ CO2 concentrations},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2008},
volume = {8},
number = {9},
pages = {2555--2568},
doi = {10.5194/acp-8-2555-2008}
}
|
| Maddy E, Barnet C, Goldberg M, Sweeney C and Liu X (2008), "CO2 retrievals from the Atmospheric Infrared Sounder: Methodology and validation", Journal of Geophysical Research: Atmospheres. Vol. 113(D11) |
BibTeX:
@article{maddy08a,
author = {Maddy, ES and Barnet, CD and Goldberg, M and Sweeney, C and Liu, X},
title = {CO2 retrievals from the Atmospheric Infrared Sounder: Methodology and validation},
journal = {Journal of Geophysical Research: Atmospheres},
year = {2008},
volume = {113},
number = {D11},
doi = {10.1029/2007JD009402/full}
}
|
| Mahata S, Wang C-H, Bhattacharya SK and Liang M-C ({2016}), "Near Surface CO2 Triple Oxygen Isotope Composition", TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES., FEB, {2016}. Vol. {27}({1}), pp. 99-106. |
| Abstract: The isotopic composition of carbon dioxide in the atmosphere is a powerful tool for constraining its sources and sinks. In particular, the O-17 oxygen anomaly [Delta O-17 = 1000 x ln(1 + delta O-17/1000) - 0.516 x 1000 x ln(1 + delta O-18/1000)], with a value > 0.5 parts per thousand produced in the middle atmosphere, provides an ideal tool for probing the exchange of carbon dioxide between the biosphere/hydrosphere and atmosphere. The biosphere/hydrosphere and anthropogenic emissions give values <= 0.3 parts per thousand. Therefore, any anomaly in near surface CO2 would reflect the balance between stratospheric input and exchange with the aforementioned surface sources. We have analyzed Delta O-17 values of CO2 separated from air samples collected in Taipei, Taiwan, located in the western Pacific region. The obtained mean anomaly is 0.42 +/- 0.14 parts per thousand (1-sigma standard deviation), in good agreement with model prediction and a published decadal record. Apart from typically used delta C-13 and delta O-18 values, the Delta O-17 value could provide an additional tracer for constraining the carbon cycle. |
BibTeX:
@article{mahata16a,
author = {Mahata, Sasadhar and Wang, Chung-Ho and Bhattacharya, Sourendra Kumar and Liang, Mao-Chang},
title = {Near Surface CO2 Triple Oxygen Isotope Composition},
journal = {TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES},
year = {2016},
volume = {27},
number = {1},
pages = {99--106},
doi = {10.3319/TAO.2015.09.16.01(A)}
}
|
| Mai B, An X, Deng X, Zhou L, Wang C, Huang J, Chen L and Yin S (2014), "Simulation analysis and verification of surface CO2 flux over Pearl River Delta, China", China Environmental Science. Vol. 34(8), pp. 1960-1971. |
BibTeX:
@article{mai14a,
author = {Mai, Boru and An, Xingqin and Deng, Xuejiao and Zhou, Lingxi and Wang, Chunlin and Huang, Jianping and Chen, Ling and Yin, Shuxian},
title = {Simulation analysis and verification of surface CO2 flux over Pearl River Delta, China},
journal = {China Environmental Science},
year = {2014},
volume = {34},
number = {8},
pages = {1960--1971},
url = {http://manu36.magtech.com.cn/Jweb_zghjkx/CN/article/downloadArticleFile.do?attachType=PDF&id=13755}
}
|
| 麦博儒, 邓雪娇, 安兴琴, 周凌晞, 谭浩波, 李菲 and 李楠 (2014), "基于碳源汇模式系统 Carbon Tracker 的广东省近地层典型 CO2 过程模拟研究", 环境科学学报. |
BibTeX:
@article{mai14b,
author = {麦博儒 and 邓雪娇 and 安兴琴 and 周凌晞 and 谭浩波 and 李菲 and 李楠},
title = {基于碳源汇模式系统 Carbon Tracker 的广东省近地层典型 CO2 过程模拟研究},
journal = {环境科学学报},
year = {2014},
url = {http://www.cqvip.com/qk/91840x/201407/663141023.html}
}
|
| Majkut JD (2014), "Variability and Trends in the Carbon Cycle". Thesis at: Princeton University. |
BibTeX:
@phdthesis{majkut14a,
author = {Majkut, Joseph Daniel},
title = {Variability and Trends in the Carbon Cycle},
school = {Princeton University},
year = {2014},
url = {http://search.proquest.com/openview/e90b562d689cf3a0ab70ffe5a30cd505/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Maki T, Ikegami M, Fujita T, Hirahara T, Yamada K, Mori K, Takeuchi A, Tsutsumi Y, Suda K and Conway TJ ({2010}), "New technique to analyse global distributions of CO2 concentrations and fluxes from non-processed observational data", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 797-809. |
| Abstract: We have developed a new observational screening technique for inverse model. This technique was applied to our transport models with re-analysed meteorological data and the inverse model to estimate the global distribution of CO2 concentrations and fluxes. During the 1990s, we estimated a total CO2 uptake by the biosphere of 1.4-1.5 PgC yr-1 and a total CO2 uptake by the oceans of 1.7-1.8 PgC yr-1. The uncertainty of global CO2 flux estimation is about 0.3 PgC yr-1. We also obtained monthly surface CO2 concentrations in the marine boundary layer to precisions of 0.5-1.0 ppm. To utilize non-processed (statistical monthly mean) observational data in our analysis, we developed a quality control procedure for such observational data including a repetition of inversion. This technique is suitable for other inversion setups. Observational data by ships were placed into grids and used in our analysis to add to the available data from fixed stations. The estimated global distributions are updated and extended every year. |
BibTeX:
@article{maki10a,
author = {Maki, T. and Ikegami, M. and Fujita, T. and Hirahara, T. and Yamada, K. and Mori, K. and Takeuchi, A. and Tsutsumi, Y. and Suda, K. and Conway, T. J.},
title = {New technique to analyse global distributions of CO2 concentrations and fluxes from non-processed observational data},
journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
year = {2010},
volume = {62},
number = {5, SI},
pages = {797--809},
doi = {10.1111/j.1600-0889.2010.00488.x}
}
|
| Maksyutov S, Takagi H, Belikov DA, Saeki T, Zhuravlev R, Ganshin A, Lukyanov A, Yoshida Y, Oshchepkov S, Bril A, Saito M, Oda T, Valsala VK, Saito R, Andres RJ, Conway T, Tans P and Yokota T ({2012}), "Estimation of regional surface CO2 fluxes with GOSAT observations using two inverse modeling approaches", In REMOTE SENSING AND MODELING OF THE ATMOSPHERE, OCEANS, AND INTERACTIONS IV. Vol. {8529} |
| Abstract: Inverse estimation of surface CO2 fluxes is performed with atmospheric transport model using ground-based and GOSAT observations. The NIES-retrieved CO2 column mixing (X-CO2) and column averaging kernel are provided by GOSAT Level 2 product v. 2.0 and PPDF-DOAS method. Monthly mean CO2 fluxes for 64 regions are estimated together with a global mean offset between GOSAT data and ground-based data. We used the fixed-lag Kalman filter to infer monthly fluxes for 42 sub-continental terrestrial regions and 22 oceanic basins. We estimate fluxes and compare results obtained by two inverse modeling approaches. In basic approach adopted in GOSAT Level 4 product v. 2.01, we use aggregation of the GOSAT observations into monthly mean over 5x5 degree grids, fluxes are estimated independently for each region, and NIES atmospheric transport model is used for forward simulation. In the alternative method, the model-observation misfit is estimated for each observation separately and fluxes are spatially correlated using EOF analysis of the simulated flux variability similar to geostatistical approach, while transport simulation is enhanced by coupling with a Lagrangian transport model Flexpart. Both methods use using the same set of prior fluxes and region maps. Daily net ecosystem exchange (NEE) is predicted by the Vegetation Integrative SImulator for Trace gases (VISIT) optimized to match seasonal cycle of the atmospheric CO2. Monthly ocean-atmosphere CO2 fluxes are produced with an ocean pCO(2) data assimilation system. Biomass burning fluxes were provided by the Global Fire Emissions Database (GFED); and monthly fossil fuel CO2 emissions are estimated with ODIAC inventory. The results of analyzing one year of the GOSAT data suggest that when both GOSAT and ground-based data are used together, fluxes in tropical and other remote regions with lower associated uncertainties are obtained than in the analysis using only ground-based data. With version 2.0 of L2 X-CO2 the fluxes appear reasonable for many regions and seasons, however there is a need for improving the L2 bias correction, data filtering and the inverse modeling method to reduce estimated flux anomalies visible in some areas. We also observe that application of spatial flux correlations with EOF-based approach reduces flux anomalies. |
BibTeX:
@inproceedings{maksyutov12a,
author = {Maksyutov, Shamil and Takagi, Hiroshi and Belikov, Dmitry A. and Saeki, Tazu and Zhuravlev, Ruslan and Ganshin, Alexander and Lukyanov, Alexander and Yoshida, Yukio and Oshchepkov, Sergey and Bril, Andrey and Saito, Makoto and Oda, Tomohiro and Valsala, Vinu K. and Saito, Ryu and Andres, Robert J. and Conway, Thomas and Tans, Pieter and Yokota, Tatsuya},
editor = {Kawamiya, M and Krishnamurti, TN and Maksyutov, S},
title = {Estimation of regional surface CO2 fluxes with GOSAT observations using two inverse modeling approaches},
booktitle = {REMOTE SENSING AND MODELING OF THE ATMOSPHERE, OCEANS, AND INTERACTIONS IV},
year = {2012},
volume = {8529},
note = {Conference on Remote Sensing and Modeling of the Atmosphere, Oceans, and Interactions IV, Kyoto, JAPAN, OCT 31-NOV 01, 2012},
doi = {10.1117/12.979664}
}
|
| Maksyutov S, Takagi H, Valsala VK, Saito M, Oda T, Saeki T, Belikov DA, Saito R, Ito A, Yoshida Y, Morino I, Uchino O, Andres RJ and Yokota T ({2013}), "Regional CO2 flux estimates for 2009-2010 based on GOSAT and ground-based CO2 observations", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({18}), pp. 9351-9373. |
| Abstract: We present the application of a global carbon cycle modeling system to the estimation of monthly regional CO2 fluxes from the column-averaged mole fractions of CO2 (X-CO2) retrieved from spectral observations made by the Greenhouse gases Observing SATellite (GOSAT). The regional flux estimates are to be publicly disseminated as the GOSAT Level 4 data product. The forward modeling components of the system include an atmospheric tracer transport model, an anthropogenic emissions inventory, a terrestrial biosphere exchange model, and an oceanic flux model. The atmospheric tracer transport was simulated using isentropic coordinates in the stratosphere and was tuned to reproduce the age of air. We used a fossil fuel emission inventory based on large point source data and observations of night-time lights. The terrestrial biospheric model was optimized by fitting model parameters to observed atmospheric CO2 seasonal cycle, net primary production data, and a biomass distribution map. The oceanic surface pCO(2) distribution was estimated with a 4-D variational data assimilation system based on reanalyzed ocean currents. Monthly CO2 fluxes of 64 sub-continental regions, between June 2009 and May 2010, were estimated from GOSAT FTS SWIR Level 2 X-CO2 retrievals (ver. 02.00) gridded to 5 degrees x 5 degrees cells and averaged on a monthly basis and monthly-mean GLOBALVIEW-CO2 data. Our result indicated that adding the GOSAT X-CO2 retrievals to the GLOBALVIEW data in the flux estimation brings changes to fluxes of tropics and other remote regions where the surface-based data are sparse. The uncertainties of these remote fluxes were reduced by as much as 60% through such addition. Optimized fluxes estimated for many of these regions, were brought closer to the prior fluxes by the addition of the GOSAT retrievals. In most of the regions and seasons considered here, the estimated fluxes fell within the range of natural flux variabilities estimated with the component models. |
BibTeX:
@article{maksyutov13a,
author = {Maksyutov, S. and Takagi, H. and Valsala, V. K. and Saito, M. and Oda, T. and Saeki, T. and Belikov, D. A. and Saito, R. and Ito, A. and Yoshida, Y. and Morino, I. and Uchino, O. and Andres, R. J. and Yokota, T.},
title = {Regional CO2 flux estimates for 2009-2010 based on GOSAT and ground-based CO2 observations},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {18},
pages = {9351--9373},
doi = {10.5194/acp-13-9351-2013}
}
|
| Mallia DV, Lin JC, Urbanski S, Ehleringer J and Nehrkorn T ({2015}), "Impacts of upwind wildfire emissions on CO, CO2, and PM2.5 concentrations in Salt Lake City, Utah", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 16, {2015}. Vol. {120}({1}), pp. 147-166. |
| Abstract: Biomass burning is known to contribute large quantities of CO2, CO, and PM2.5 to the atmosphere. Biomass burning not only affects the area in the vicinity of fire but may also impact the air quality far downwind from the fire. The 2007 and 2012 western U.S. wildfire seasons were characterized by significant wildfire activity across much of the Intermountain West and California. In this study, we determined the locations of wildfire-derived emissions and their aggregate impacts on Salt Lake City, a major urban center downwind of the fires. To determine the influences of biomass burning emissions, we initiated an ensemble of stochastic back trajectories at the Salt Lake City receptor within the Stochastic Time-Inverted Lagrangian Transport (STILT) model, driven by wind fields from the Weather Research and Forecasting (WRF) model. The trajectories were combined with a new, high-resolution biomass burning emissions inventorythe Wildfire Emissions Inventory. Initial results showed that the WRF-STILT model was able to replicate many periods of enhanced wildfire activity observed in the measurements. Most of the contributions for the 2007 and 2012 wildfire seasons originated from fires located in Utah and central Idaho. The model results suggested that during intense episodes of upwind wildfires in 2007 and 2012, fires contributed as much as 250ppb of CO during a 3 h period and 15 mu g/m(3) of PM2.5 averaged over 24 h at Salt Lake City. Wildfires had a much smaller impact on CO2 concentrations in Salt Lake City, with contributions rarely exceeding 2ppm enhancements. Key Points |
BibTeX:
@article{mallia15a,
author = {Mallia, D. V. and Lin, J. C. and Urbanski, S. and Ehleringer, J. and Nehrkorn, T.},
title = {Impacts of upwind wildfire emissions on CO, CO2, and PM2.5 concentrations in Salt Lake City, Utah},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2015},
volume = {120},
number = {1},
pages = {147--166},
doi = {10.1002/2014JD022472}
}
|
| Manning AC, Nisbet EG, Keeling RF and Liss PS ({2011}), "Greenhouse gases in the Earth system: setting the agenda to 2030", PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES., MAY 28, {2011}. Vol. {369}({1943}), pp. 1885-1890. |
| Abstract: What do we need to know about greenhouse gases? Over the next 20 years, how should scientists study the role of greenhouse gases in the Earth system and the changes that are taking place? These questions were addressed at a Royal Society scientific Discussion Meeting in London on 22-23 February 2010, with over 300 participants. |
BibTeX:
@article{manning11a,
author = {Manning, Andrew C. and Nisbet, Euan G. and Keeling, Ralph F. and Liss, Peter S.},
title = {Greenhouse gases in the Earth system: setting the agenda to 2030},
journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES},
year = {2011},
volume = {369},
number = {1943},
pages = {1885--1890},
doi = {10.1098/rsta.2011.0076}
}
|
| Marino BD (2010), "System of systems for monitoring greenhouse gas fluxes". |
BibTeX:
@misc{marino10a,
author = {Marino, Bruno DV},
title = {System of systems for monitoring greenhouse gas fluxes},
publisher = {Google Patents},
year = {2010},
url = {https://patents.google.com/patent/US20100198736A1/en}
}
|
| Marquis M and Tans P ({2008}), "Climate change - Carbon crucible", SCIENCE., APR 25, {2008}. Vol. {320}({5875}), pp. 460-461. |
BibTeX:
@article{marquis08a,
author = {Marquis, Melinda and Tans, Pieter},
title = {Climate change - Carbon crucible},
journal = {SCIENCE},
year = {2008},
volume = {320},
number = {5875},
pages = {460--461},
doi = {10.1126/science.1156451}
}
|
| Martin CR, Zeng N, Karion A, Mueller K, Ghosh S, Lopez-Coto I, Gurney KR, Oda T, Prasad K, Liu J, Dickerson R and Whetstone J (2019), "Investigating sources of variability and error in simulations of carbon dioxide in an urban region", ATMOSPHERIC ENVIRONMENT., FEB, 2019. Vol. 199, pp. 55-69. |
BibTeX:
@article{martin19a,
author = {Martin, Cory R. and Zeng, N. and Karion, A. and Mueller, K. and Ghosh, S. and Lopez-Coto, I. and Gurney, K. R. and Oda, T. and Prasad, K. and Liu, J. and Dickerson, R.R. and Whetstone, J.},
title = {Investigating sources of variability and error in simulations of carbon dioxide in an urban region},
journal = {ATMOSPHERIC ENVIRONMENT},
year = {2019},
volume = {199},
pages = {55-69},
url = {https://www.sciencedirect.com/science/article/pii/S1352231018307799}
}
|
| Martins DK, Sweeney C, Stirm BH and Shepson PB ({2009}), "Regional surface flux of CO2 inferred from changes in the advected CO2 column density", AGRICULTURAL AND FOREST METEOROLOGY., OCT 1, {2009}. Vol. {149}({10}), pp. 1674-1685. |
| Abstract: A Lagrangian experiment was conducted over Iowa during the daytime (9:00-17:30 LT) on June 19,2007 as part of the North American Carbon Program's Mid-Continent Intensive using a light-weight and operationally flexible aircraft to measure a net drawdown of CO2 concentration within the boundary layer. The drawdown can be related to net ecosystem exchange when anthropogenic emissions are estimated using a combination of the Vulcan fossil fuel emissions inventory coupled with a source contribution analysis using HYSPLIT. Results show a temporally and spatially averaged net CO2 flux Of -9.0 +/- 2.4 mu mol m(-2) s(-1) measured from the aircraft data. The average flux from anthropogenic emissions over the measurement area was 0.3 +/- 0.1 mu mol CO2 m(-2) s(-1). Large-scale subsidence occurred during the experiment, entraining 1.0 +/- 0.2 mu mol CO2 m(-2) s(-1) into the boundary layer. Thus, the CO2 flux attributable to the vegetation and soils is -10.3 +/- 2.4 mu mol m(-2) s(-1). The magnitude of the calculated daytime biospheric flux is consistent with tower-based eddy covariance fluxes over corn and soybeans given existing land-use estimates for this agricultural region. Flux values are relatively insensitive to the choice of integration height above the boundary layer and emission footprint area. Flux uncertainties are relatively small compared to the biospheric fluxes, though the measurements were conducted at the height of the growing season. (C) 2009 Elsevier B.V. All rights reserved. |
BibTeX:
@article{martins09a,
author = {Martins, Douglas K. and Sweeney, Colm and Stirm, Brian H. and Shepson, Paul B.},
title = {Regional surface flux of CO2 inferred from changes in the advected CO2 column density},
journal = {AGRICULTURAL AND FOREST METEOROLOGY},
year = {2009},
volume = {149},
number = {10},
pages = {1674--1685},
doi = {10.1016/j.agrformet.2009.05.005}
}
|
| Martins DK (2009), "Development of methods for measurement of biosphere-atmosphere exchange of carbon and nitrogen". Thesis at: Purdue University. |
BibTeX:
@phdthesis{martins09b,
author = {Martins, Douglas K},
title = {Development of methods for measurement of biosphere-atmosphere exchange of carbon and nitrogen},
school = {Purdue University},
year = {2009},
url = {http://search.proquest.com/openview/fbdc1f23ed5696bf082a793577dd4459/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Masarie KA, Petron G, Andrews A, Bruhwiler L, Conway TJ, Jacobson AR, Miller JB, Tans PP, Worthy DE and Peters W ({2011}), "Impact of CO2 measurement bias on CarbonTracker surface flux estimates", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., SEP 9, {2011}. Vol. {116} |
| Abstract: For over 20 years, atmospheric measurements of CO2 dry air mole fractions have been used to derive estimates of CO2 surface fluxes. Historically, only a few research laboratories made these measurements. Today, many laboratories are making CO2 observations using a variety of analysis techniques and, in some instances, using different calibration scales. As a result, the risk of biases in individual CO2 mole fraction records, or even in complete monitoring networks, has increased over the last decades. Ongoing experiments comparing independent, well-calibrated measurements of atmospheric CO2 show that biases can and do exist between measurement records. Biases in measurements create artificial spatial and temporal CO2 gradients, which are then interpreted by an inversion system, leading to erroneous flux estimates. Here we evaluate the impact of a constant bias introduced into the National Oceanic and Atmospheric Administration (NOAA) quasi-continuous measurement record at the Park Falls, Wisconsin (LEF), tall tower site on CarbonTracker flux estimates. We derive a linear relationship between the magnitude of the introduced bias at LEF and the CarbonTracker surface flux responses. Temperate North American net flux estimates are most sensitive to a bias at LEF in our CarbonTracker inversion, and its linear response rate is 68 Tg C yr(-1) (similar to 10% of the estimated North American annual terrestrial uptake) for every 1 ppm of bias in the LEF record. This sensitivity increases when (1) measurement biases approached assumed model errors and (2) fewer other measurement records are available to anchor the flux estimates despite the presence of bias in one record. Flux estimate errors are also calculated beyond North America. For example, biospheric uptake in Europe and boreal Eurasia combined increases by 25 Tg C yr(-1) per ppm CO2 to partially compensate for changes in the North American flux totals. These results illustrate the importance of well-calibrated, high-precision CO2 dry air mole fraction measurements, as well as the value of an effective strategy for detecting bias in measurements. This study stresses the need for a monitoring network with the necessary density to anchor regional, continental, and hemispheric fluxes more tightly and to lessen the impact of potentially undetected biases in observational networks operated by different national and international research programs. |
BibTeX:
@article{masarie11a,
author = {Masarie, K. A. and Petron, G. and Andrews, A. and Bruhwiler, L. and Conway, T. J. and Jacobson, A. R. and Miller, J. B. and Tans, P. P. and Worthy, D. E. and Peters, W.},
title = {Impact of CO2 measurement bias on CarbonTracker surface flux estimates},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2011JD016270}
}
|
| Masarie KA, Peters W, Jacobson AR and Tans PP ({2014}), "ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas measurements", EARTH SYSTEM SCIENCE DATA. Vol. {6}({2}), pp. 375-384. |
| Abstract: Observation Package (ObsPack) is a framework designed to bring together atmospheric greenhouse gas observations from a variety of sampling platforms, prepare them with specific applications in mind, and package and distribute them in a self-consistent and well-documented product. Data products created using the ObsPack framework (called ``ObsPack products'') are intended to support carbon cycle modeling studies and represent a next generation of value-added greenhouse gas observation products modeled after the cooperative GLOBALVIEW products introduced in 1996. Depending on intended use, ObsPack products may include data in their original form reformatted using the ObsPack framework or may contain derived data consisting of averages, subsets, or smoothed representations of original data. All products include extensive ancillary information (metadata) intended to help ensure the data are used appropriately, their calibration and quality assurance history are clearly described, and that individuals responsible for the measurements (data providers or principal investigators (PIs)) are properly acknowledged for their work. ObsPack products are made freely available using a distribution strategy designed to improve communication between data providers and product users. The strategy includes a data usage policy that requires users to directly communicate with data providers and an automated e-mail notification system triggered when a product is accessed. ObsPack products will be assigned a unique digital object identifier (DOI) to ensure each product can be unambiguously identified in scientific literature. Here we describe the ObsPack framework and its potential role in supporting the evolving needs of both data providers and product users. |
BibTeX:
@article{masarie14a,
author = {Masarie, K. A. and Peters, W. and Jacobson, A. R. and Tans, P. P.},
title = {ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas measurements},
journal = {EARTH SYSTEM SCIENCE DATA},
year = {2014},
volume = {6},
number = {2},
pages = {375--384},
doi = {10.5194/essd-6-375-2014}
}
|
| Medvigy D and Moorcroft PR ({2012}), "Predicting ecosystem dynamics at regional scales: an evaluation of a terrestrial biosphere model for the forests of northeastern North America", PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES., JAN 19, {2012}. Vol. {367}({1586}), pp. 222-235. |
| Abstract: Terrestrial biosphere models are important tools for diagnosing both the current state of the terrestrial carbon cycle and forecasting terrestrial ecosystem responses to global change. While there are a number of ongoing assessments of the short-term predictive capabilities of terrestrial biosphere models using flux-tower measurements, to date there have been relatively few assessments of their ability to predict longer term, decadal-scale biomass dynamics. Here, we present the results of a regional-scale evaluation of the Ecosystem Demography version 2 (ED2)-structured terrestrial biosphere model, evaluating the model's predictions against forest inventory measurements for the northeast USA and Quebec from 1985 to 1995. Simulations were conducted using a default parametrization, which used parameter values from the literature, and a constrained model parametrization, which had been developed by constraining the model's predictions against 2 years of measurements from a single site, Harvard Forest (42.5 degrees N, 72.1 degrees W). The analysis shows that the constrained model parametrization offered marked improvements over the default model formulation, capturing large-scale variation in patterns of biomass dynamics despite marked differences in climate forcing, land-use history and species-composition across the region. These results imply that data-constrained parametrizations of structured biosphere models such as ED2 can be successfully used for regional-scale ecosystem prediction and forecasting. We also assess the model's ability to capture sub-grid scale heterogeneity in the dynamics of biomass growth and mortality of different sizes and types of trees, and then discuss the implications of these analyses for further reducing the remaining biases in the model's predictions. |
BibTeX:
@article{medvigy12a,
author = {Medvigy, David and Moorcroft, Paul R.},
title = {Predicting ecosystem dynamics at regional scales: an evaluation of a terrestrial biosphere model for the forests of northeastern North America},
journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES},
year = {2012},
volume = {367},
number = {1586},
pages = {222--235},
doi = {10.1098/rstb.2011.0253}
}
|
| Meirink JF, Bergamaschi P, Frankenberg C, d'Amelio MTS, Dlugokencky EJ, Gatti LV, Houweling S, Miller JB, Roeckmann T, Villani MG and Krol MC ({2008}), "Four-dimensional variational data assimilation for inverse modeling of atmospheric methane emissions: Analysis of SCIAMACHY observations", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., SEP 4, {2008}. Vol. {113}({D17}) |
| Abstract: Recent observations from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument aboard ENVISAT have brought new insights in the global distribution of atmospheric methane. In particular, the observations showed higher methane concentrations in the tropics than previously assumed. Here, we analyze the SCIAMACHY observations and their implications for emission estimates in detail using a four-dimensional variational (4D-Var) data assimilation system. We focus on the period September to November 2003 and on the South American continent, for which the satellite observations showed the largest deviations from model simulations. In this set-up the advantages of the 4D-Var approach and the zooming capability of the underlying TM5 atmospheric transport model are fully exploited. After application of a latitude-dependent bias correction to the SCIAMACHY observations, the assimilation system is able to accurately fit those observations, while retaining consistency with a network of surface methane measurements. The main emission increments resulting from the inversion are an increase in the tropics, a decrease in South Asia, and a decrease at northern hemispheric high latitudes. The SCIAMACHY observations yield considerable additional emission uncertainty reduction, particularly in the (sub-)tropical regions, which are poorly constrained by the surface network. For tropical South America, the inversion suggests more than a doubling of emissions compared to the a priori during the 3 months considered. Extensive sensitivity experiments, in which key assumptions of the inversion set-up are varied, show that this finding is robust. Independent airborne observations in the Amazon basin support the presence of considerable local methane sources. However, these observations also indicate that emissions from eastern South America may be smaller than estimated from SCIAMACHY observations. In this respect it must be realized that the bias correction applied to the satellite observations does not take into account potential regional systematic errors, which - if identified in the future - will lead to shifts in the overall distribution of emission estimates. |
BibTeX:
@article{meirink08a,
author = {Meirink, Jan Fokke and Bergamaschi, Peter and Frankenberg, Christian and d'Amelio, Monica T. S. and Dlugokencky, Edward J. and Gatti, Luciana V. and Houweling, Sander and Miller, John B. and Roeckmann, Thomas and Villani, M. Gabriella and Krol, Maarten C.},
title = {Four-dimensional variational data assimilation for inverse modeling of atmospheric methane emissions: Analysis of SCIAMACHY observations},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2008},
volume = {113},
number = {D17},
doi = {10.1029/2007JD009740}
}
|
| Mekonnen ZA (2015), "Modeling the impacts of recent climate change on ecosystem productivity across North America". Thesis at: University of Alberta. |
BibTeX:
@phdthesis{mekonnen15a,
author = {Mekonnen, Zelalem A},
title = {Modeling the impacts of recent climate change on ecosystem productivity across North America},
school = {University of Alberta},
year = {2015},
url = {https://era.library.ualberta.ca/files/3r074x723}
}
|
| Mekonnen ZA, Grant RF and Schwalm C ({2017}), "Carbon sources and sinks of North America as affected by major drought events during the past 30 years", AGRICULTURAL AND FOREST METEOROLOGY., OCT 15, {2017}. Vol. {244}, pp. 42-56. |
| Abstract: The North American (NA) terrestrial biosphere has been a long-term carbon sink but impacts of climate extremes such as drought on ecosystem carbon exchange remain largely uncertain. Here, changes in biospheric carbon fluxes with recent climate change and impacts of the major droughts of the past 30 years on continental carbon cycle across NA were studied using a comprehensive mathematical process model, ecosys. In test of these model responses at continental scale, the spatial anomalies in modeled leaf area indices, fully prognostic in the model, from long-term (1980-2010) means during major drought events in 1988 and 2002 agreed well with those in AVHRR NDVI (R-2 = 0.84 in 1988, 0.71 in 2002). Net ecosystem productivity (NEP) modeled across NA declined by 92% (0.50 Pg C yr(-1)) and 90% (0.49 Pg C yr(-1)) from the long-term mean (+0.54 Pg C yr(-1)), in 1988 and 2002 respectively. These significant drops in NEP offset 28% of the carbon gains modeled over the last three decades. Although the long-term average modeled terrestrial carbon sink was estimated to offset similar to 30% of the fossil fuel emissions of NA, only 0.03% and 3.2% were offset in 1988 and 2002 leaving almost all fossil fuel emissions to the atmosphere. These major drought events controlled much of the continental-scale interannual variability and mainly occurred in parts of the Great Plains, southwest US and northern Mexico. Although warming in northern ecosystems caused increasing carbon sinks to be modeled as a result of greater gross primary productivity with longer growing seasons, elsewhere in the continent frequent drought events of the past 30 years reduced carbon uptake and hence net carbon sinks of the NA. |
BibTeX:
@article{mekonnen17a,
author = {Mekonnen, Zelalem A. and Grant, Robert F. and Schwalm, Christopher},
title = {Carbon sources and sinks of North America as affected by major drought events during the past 30 years},
journal = {AGRICULTURAL AND FOREST METEOROLOGY},
year = {2017},
volume = {244},
pages = {42--56},
doi = {10.1016/j.agrformet.2017.05.006}
}
|
| Mengistu AG and Mengistu Tsidu G (2018), "Comparison of CO2 from NOAA Carbon Tracker reanalysis model and satellites over Africa", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. 2018, pp. 1-31. |
BibTeX:
@article{mengistua18a,
author = {Mengistu, A. G. and Mengistu Tsidu, G.},
title = {Comparison of CO2 from NOAA Carbon Tracker reanalysis model and satellites over Africa},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2018},
volume = {2018},
pages = {1-31},
url = {https://www.atmos-meas-tech-discuss.net/amt-2018-84/amt-2018-84.pdf}
}
|
| Messerschmidt J, Parazoo N, Wunch D, Deutscher NM, Roehl C, Warneke T and Wennberg PO ({2013}), "Evaluation of seasonal atmosphere-biosphere exchange estimations with TCCON measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({10}), pp. 5103-5115. |
| Abstract: We evaluate three estimates of the atmosphere-biosphere exchange against total column CO2 observations from the Total Carbon Column Observing Network (TCCON). Using the GEOS-Chem transport model, we produce forward simulations of atmospheric CO2 concentrations for the 2006-2010 time period using the Carnegie-Ames-Stanford Approach (CASA), the Simple Biosphere (SiB) and the GBiome-BGC models. Large differences in the CO2 simulations result from the choice of the atmosphere-biosphere model. We evaluate the seasonal cycle phase, amplitude and shape of the simulations. The version of CASA currently used as the a priori model by the GEOS-Chem carbon cycle community poorly represents the season cycle in total column CO2. Consistent with earlier studies, enhancing the CO2 uptake in the boreal forest and shifting the onset of the growing season earlier significantly improve the simulated seasonal CO2 cycle using CASA estimates. The SiB model gives a better representation of the seasonal cycle dynamics. The difference in the seasonality of net ecosystem exchange (NEE) between these models is not the absolute gross primary productivity (GPP), but rather the differential phasing of ecosystem respiration (RE) with respect to GPP between these models. |
BibTeX:
@article{messerschmidt13a,
author = {Messerschmidt, J. and Parazoo, N. and Wunch, D. and Deutscher, N. M. and Roehl, C. and Warneke, T. and Wennberg, P. O.},
title = {Evaluation of seasonal atmosphere-biosphere exchange estimations with TCCON measurements},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {10},
pages = {5103--5115},
doi = {10.5194/acp-13-5103-2013}
}
|
| Miles NL, Richardson SJ, Davis KJ, Lauvaux T, Andrews AE, West TO, Bandaru V and Crosson ER ({2012}), "Large amplitude spatial and temporal gradients in atmospheric boundary layer CO2 mole fractions detected with a tower-based network in the U.S. upper Midwest", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., FEB 21, {2012}. Vol. {117} |
| Abstract: This study presents observations of atmospheric boundary layer CO2 mole fraction from a nine-tower regional network deployed during the North American Carbon Program's Mid-Continent Intensive (MCI) during 2007-2009. The MCI region is largely agricultural, with well-documented carbon exchange available via agricultural inventories. By combining vegetation maps and tower footprints, we show the fractional influence of corn, soy, grass, and forest biomes varies widely across the MCI. Differences in the magnitude of CO2 flux from each of these biomes lead to large spatial gradients in the monthly averaged CO2 mole fraction observed in the MCI. In other words, the monthly averaged gradients are tied to regional patterns in net ecosystem exchange (NEE). The daily scale gradients are more weakly connected to regional NEE, instead being governed by local weather and large-scale weather patterns. With this network of tower-based mole fraction measurements, we detect climate-driven interannual changes in crop growth that are confirmed by satellite and inventory methods. These observations show that regional-scale CO2 mole fraction networks yield large, coherent signals governed largely by regional sources and sinks of CO2. |
BibTeX:
@article{miles12a,
author = {Miles, Natasha L. and Richardson, Scott J. and Davis, Kenneth J. and Lauvaux, Thomas and Andrews, Arlyn E. and West, Tristram O. and Bandaru, Varaprasad and Crosson, Eric R.},
title = {Large amplitude spatial and temporal gradients in atmospheric boundary layer CO2 mole fractions detected with a tower-based network in the U.S. upper Midwest},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2012},
volume = {117},
doi = {10.1029/2011JG001781}
}
|
| Miller SM, Matross DM, Andrews AE, Millet DB, Longo M, Gottlieb EW, Hirsch AI, Gerbig C, Lin JC, Daube BC, Hudman RC, Dias PLS, Chow VY and Wofsy SC ({2008}), "Sources of carbon monoxide and formaldehyde in North America determined from high-resolution atmospheric data", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {8}({24}), pp. 7673-7696. |
| Abstract: We analyze the North American budget for carbon monoxide using data for CO and formaldehyde concentrations from tall towers and aircraft in a model-data assimilation framework. The Stochastic Time-Inverted Lagrangian Transport model for CO (STILT-CO) determines local to regional-scale CO contributions associated with production from fossil fuel combustion, biomass burning, and oxidation of volatile organic compounds (VOCs) using an ensemble of Lagrangian particles driven by high resolution assimilated meteorology. In many cases, the model demonstrates high fidelity simulations of hourly surface data from tall towers and point measurements from aircraft, with somewhat less satisfactory performance in coastal regions and when CO from large biomass fires in Alaska and the Yukon Territory influence the continental US. Inversions of STILT-CO simulations for CO and formaldehyde show that current inventories of CO emissions from fossil fuel combustion are significantly too high, by almost a factor of three in summer and a factor two in early spring, consistent with recent analyses of data from the INTEXA aircraft program. Formaldehyde data help to show that sources of CO from oxidation of CH4 and other VOCs represent the dominant sources of CO over North America in summer. |
BibTeX:
@article{miller08a,
author = {Miller, S. M. and Matross, D. M. and Andrews, A. E. and Millet, D. B. and Longo, M. and Gottlieb, E. W. and Hirsch, A. I. and Gerbig, C. and Lin, J. C. and Daube, B. C. and Hudman, R. C. and Dias, P. L. S. and Chow, V. Y. and Wofsy, S. C.},
title = {Sources of carbon monoxide and formaldehyde in North America determined from high-resolution atmospheric data},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2008},
volume = {8},
number = {24},
pages = {7673--7696},
doi = {10.5194/acp-8-7673-2008}
}
|
| Miller JB, Lehman SJ, Montzka SA, Sweeney C, Miller BR, Karion A, Wolak C, Dlugokencky EJ, Southon J, Turnbull JC and Tans PP ({2012}), "Linking emissions of fossil fuel CO2 and other anthropogenic trace gases using atmospheric (CO2)-C-14", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., APR 19, {2012}. Vol. {117} |
| Abstract: Atmospheric CO2 gradients are usually dominated by the signal from net terrestrial biological fluxes, despite the fact that fossil fuel combustion fluxes are larger in the annual mean. Here, we use a six year long series of (CO2)-C-14 and CO2 measurements obtained from vertical profiles at two northeast U.S. aircraft sampling sites to partition lower troposphere CO2 enhancements (and depletions) into terrestrial biological and fossil fuel components (C-bio and C-ff). Mean C-ff is 1.5 ppm, and 2.4 ppm when we consider only planetary boundary layer samples. However, we find that the contribution of C-bio to CO2 enhancements is large throughout the year, and averages 60% in winter. Paired observations of C-ff and the lower troposphere enhancements (Delta(gas)) of 22 other anthropogenic gases (CH4, CO, halo- and hydrocarbons and others) measured in the same samples are used to determine apparent emission ratios for each gas. We then scale these ratios by the well known U.S. fossil fuel CO2 emissions to provide observationally based estimates of national emissions for each gas and compare these to ``bottom up'' estimates from inventories. Correlations of Delta(gas) with C-ff for almost all gases are statistically significant with median r(2) for winter, summer and the entire year of 0.59, 0.45, and 0.42, respectively. Many gases exhibit statistically significant winter: summer differences in ratios that indicate seasonality of emissions or chemical destruction. The variability of ratios in a given season is not readily attributable to meteorological or geographic variables and instead most likely reflects real, short-term spatiotemporal variability of emissions. |
BibTeX:
@article{miller12a,
author = {Miller, John B. and Lehman, Scott J. and Montzka, Stephen A. and Sweeney, Colm and Miller, Benjamin R. and Karion, Anna and Wolak, Chad and Dlugokencky, Ed J. and Southon, John and Turnbull, Jocelyn C. and Tans, Pieter P.},
title = {Linking emissions of fossil fuel CO2 and other anthropogenic trace gases using atmospheric (CO2)-C-14},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2012},
volume = {117},
doi = {10.1029/2011JD017048}
}
|
| Miller SM, Michalak AM and Levi PJ ({2014}), "Atmospheric inverse modeling with known physical bounds: an example from trace gas emissions", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {7}({1}), pp. 303-315. |
| Abstract: Many inverse problems in the atmospheric sciences involve parameters with known physical constraints. Examples include nonnegativity (e. g., emissions of some urban air pollutants) or upward limits implied by reaction or solubility constants. However, probabilistic inverse modeling approaches based on Gaussian assumptions cannot incorporate such bounds and thus often produce unrealistic results. The atmospheric literature lacks consensus on the best means to overcome this problem, and existing atmospheric studies rely on a limited number of the possible methods with little examination of the relative merits of each. This paper investigates the applicability of several approaches to bounded inverse problems. A common method of data transformations is found to unrealistically skew estimates for the examined example application. The method of Lagrange multipliers and two Markov chain Monte Carlo (MCMC) methods yield more realistic and accurate results. In general, the examined MCMC approaches produce the most realistic result but can require substantial computational time. Lagrange multipliers offer an appealing option for large, computationally intensive problems when exact uncertainty bounds are less central to the analysis. A synthetic data inversion of US anthropogenic methane emissions illustrates the strengths and weaknesses of each approach. |
BibTeX:
@article{miller14a,
author = {Miller, S. M. and Michalak, A. M. and Levi, P. J.},
title = {Atmospheric inverse modeling with known physical bounds: an example from trace gas emissions},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2014},
volume = {7},
number = {1},
pages = {303--315},
doi = {10.5194/gmd-7-303-2014}
}
|
| Miller SM, Hayek MN, Andrews AE, Fung I and Liu J ({2015}), "Biases in atmospheric CO2 estimates from correlated meteorology modeling errors", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({5}), pp. 2903-2914. |
| Abstract: Estimates of CO2 fluxes that are based on atmospheric measurements rely upon a meteorology model to simulate atmospheric transport. These models provide a quantitative link between the surface fluxes and CO2 measurements taken downwind. Errors in the meteorology can therefore cause errors in the estimated CO2 fluxes. Meteorology errors that correlate or covary across time and/or space are particularly worrisome; they can cause biases in modeled atmospheric CO2 that are easily confused with the CO2 signal from surface fluxes, and they are difficult to characterize. In this paper, we leverage an ensemble of global meteorology model outputs combined with a data assimilation system to estimate these biases in modeled atmospheric CO2. In one case study, we estimate the magnitude of month-long CO2 biases relative to CO2 boundary layer enhancements and quantify how that answer changes if we either include or remove error correlations or covariances. In a second case study, we investigate which meteorological conditions are associated with these CO2 biases. In the first case study, we estimate uncertainties of 0.57 ppm in monthly-averaged CO2 concentrations, depending upon location (95br> confidence interval). These uncertainties correspond to 13-150% of the mean afternoon CO2 boundary layer enhancement at individual observation sites. When we remove error covariances, however, this range drops to 222 %. Top-down studies that ignore these covariances could therefore underestimate the uncertainties and/or propagate transport errors into the flux estimate. In the second case study, we find that these month-long errors in atmospheric transport are anti-correlated with temperature and planetary boundary layer (PBL) height over terrestrial regions. In marine environments, by contrast, these errors are more strongly associated with weak zonal winds. Many errors, however, are not correlated with a single meteorological parameter, suggesting that a single meteorological proxy is not sufficient to characterize uncertainties in atmospheric CO2. Together, these two case studies provide information to improve the setup of future top-down inverse modeling studies, preventing unforeseen biases in estimated CO2 fluxes. |
BibTeX:
@article{miller15a,
author = {Miller, S. M. and Hayek, M. N. and Andrews, A. E. and Fung, I. and Liu, J.},
title = {Biases in atmospheric CO2 estimates from correlated meteorology modeling errors},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2015},
volume = {15},
number = {5},
pages = {2903--2914},
doi = {10.5194/acp-15-2903-2015}
}
|
| Mingwei Z, Tianxiang Y, Xingying Z, Jinglu S, Ling J and Chun W ({2017}), "Fusion of multi-source near-surface CO2 concentration data based on high accuracy surface modeling", ATMOSPHERIC POLLUTION RESEARCH., NOV, {2017}. Vol. {8}({6}), pp. 1170-1178. |
| Abstract: Under the background of growing greenhouse gas emissions and the resulting global warming, researches about the spatial-temporal variation analysis of the concentration of carbon dioxide in the regional and global scale has become one of the most important topics in the scientific community. Simulating and analyzing the spatial-temporal variation of the carbon dioxide concentration on a global scale under limited observation data has become one of the key problems to be solved in the research field of spatial analysis technology. A new research approach based on high accuracy surface modeling data fusion (HASM-DF) method was proposed in this paper, in which the output of the CO2 concentration of the GEOS-Chem model were taken as driving field, and the observation values of CO2 concentration at ground observation station were taken as accuracy control conditions. The new approach's objective is to fulfill the fusion of the two kinds of CO2 data, and obtain the distribution of CO2 on a global scale with a higher accuracy than the results of GEOS-Chem. Root mean square error (RMSE) was chosen as the basic accuracy index, and the experimental analysis shows that the RMSE of the result of the proposed approach is 1.886 ppm, which is significantly lower than that of the GEOS-Chem's 2.239 ppm. Furthermore, compared with the results created by the interpolation methods used the observation values at stations; the fusion results keep a good spatial heterogeneity similar to the results of GEOS-Chem. This research analyzed the spatial distribution and time series variation of the near-surface CO2 based on the fusion result on a global scale. And it can found that areas such as East Asia, Western North American, Central South America and Central Africa and other region show a relatively high value of the near-surface CO2 concentration. And we also found that the near-surface CO2 concentration changes with season, especially in North America and Eurasia, the near-surface CO2 in summer was significantly lower than winter in these areas. (C) 2017 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved. |
BibTeX:
@article{mingwei17a,
author = {Zhao Mingwei and Yue Tianxiang and Zhang Xingying and Sun Jinglu and Jiang Ling and Wang Chun},
title = {Fusion of multi-source near-surface CO2 concentration data based on high accuracy surface modeling},
journal = {ATMOSPHERIC POLLUTION RESEARCH},
year = {2017},
volume = {8},
number = {6},
pages = {1170--1178},
doi = {10.1016/j.apr.2017.05.003}
}
|
| Mitchell LE, Lin JC, Bowling DR, Pataki DE, Strong C, Schauer AJ, Bares R, Bush SE, Stephens BB, Mendoza D, Mallia D, Holland L, Gurney KR and Ehleringer JR ({2018}), "Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth", PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA., MAR 20, {2018}. Vol. {115}({12}), pp. {2912-2917}. |
| Abstract: Cities are concentrated areas of CO2 emissions and have become the foci of policies for mitigation actions. However, atmospheric measurement networks suitable for evaluating urban emissions over time are scarce. Here we present a unique long-term (decadal) record of CO2 mole fractions from five sites across Utah's metropolitan Salt Lake Valley. We examine ``excess'' CO2 above background conditions resulting from local emissions and meteorological conditions. We ascribe CO2 trends to changes in emissions, since we did not find long-term trends in atmospheric mixing proxies. Three contrasting CO2 trends emerged across urban types: negative trends at a residential-industrial site, positive trends at a site surrounded by rapid suburban growth, and relatively constant CO2 over time at multiple sites in the established, residential, and commercial urban core. Analysis of population within the atmospheric footprints of the different sites reveals approximately equal increases in population influencing the observed CO2, implying a nonlinear relationship with CO2 emissions: Population growth in rural areas that experienced suburban development was associated with increasing emissions while population growth in the developed urban core was associated with stable emissions. Four state-of-the-art global-scale emission inventories also have a nonlinear relationship with population density across the city; however, in contrast to our observations, they all have nearly constant emissions over time. Our results indicate that decadal scale changes in urban CO2 emissions are detectable through monitoring networks and constitute a valuable approach to evaluate emission inventories and studies of urban carbon cycles. |
BibTeX:
@article{mitchell18a,
author = {Mitchell, Logan E. and Lin, John C. and Bowling, David R. and Pataki, Diane E. and Strong, Courtenay and Schauer, Andrew J. and Bares, Ryan and Bush, Susan E. and Stephens, Britton B. and Mendoza, Daniel and Mallia, Derek and Holland, Lacey and Gurney, Kevin R. and Ehleringer, James R.},
title = {Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth},
journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
year = {2018},
volume = {115},
number = {12},
pages = {2912-2917},
doi = {{10.1073/pnas.1702393115}}
}
|
| Mogollon R and Calil PHR ({2018}), "Counterintuitive effects of global warming-induced wind patterns on primary production in the Northern Humboldt Current System", GLOBAL CHANGE BIOLOGY., JUL, {2018}. Vol. {24}({7}), pp. {3187-3198}. |
| Abstract: It has been hypothesized that global warming will strengthen upwelling-favorable winds in the Northern Humboldt Current System (NHCS) as a consequence of the increase of the land-sea thermal gradient along the Peruvian coast. The effect of strengthened winds in this region is assessed with the use of a coupled physical-biogeochemical model forced with projected and climatological winds. Strengthened winds induce an increase in primary production of 2% per latitudinal degree from 9.5 degrees S to 5 degrees S. In some important coastal upwelling sites primary production is reduced. This is due to a complex balance between nutrient availability, nutrient use efficiency, as well as eddy- and wind-driven factors. Mesoscale activity induces a net offshore transport of inorganic nutrients, thus reducing primary production in the coastal upwelling region. Wind mixing, in general disadvantageous for primary producers, leads to shorter residence times in the southern and central coastal zones. Overall, instead of a proportional enhancement in primary production due to increased winds, the NHCS becomes only 5% more productive (+5molCm(-2) year(-1)), 10% less limited by nutrients and 15% less efficient due to eddy-driven effects. It is found that regions with a initial strong nutrient limitation are more efficient in terms of nutrient assimilation which makes them more resilient in face of the acceleration of the upwelling circulation. |
BibTeX:
@article{mogollon18a,
author = {Mogollon, Rodrigo and Calil, Paulo H. R.},
title = {Counterintuitive effects of global warming-induced wind patterns on primary production in the Northern Humboldt Current System},
journal = {GLOBAL CHANGE BIOLOGY},
year = {2018},
volume = {24},
number = {7},
pages = {3187-3198},
doi = {{10.1111/gcb.14171}}
}
|
| van der Molen MK, de Jeu RAM, Wagner W, van der Velde IR, Kolari P, Kurbatova J, Varlagin A, Maximov TC, Kononov AV, Ohta T, Kotani A, Krol MC and Peters W ({2016}), "The effect of assimilating satellite-derived soil moisture data in SiBCASA on simulated carbon fluxes in Boreal Eurasia", HYDROLOGY AND EARTH SYSTEM SCIENCES. Vol. {20}({2}), pp. 605-624. |
| Abstract: Boreal Eurasia is a region where the interaction between droughts and the carbon cycle may have significant impacts on the global carbon cycle. Yet the region is extremely data sparse with respect to meteorology, soil moisture, and carbon fluxes as compared to e.g. Europe. To better constrain our vegetation model SiBCASA, we increase data usage by assimilating two streams of satellite-derived soil moisture. We study whether the assimilation improved SiBCASA's soil moisture and its effect on the simulated carbon fluxes. By comparing to unique in situ soil moisture observations, we show that the passive microwave soil moisture product did not improve the soil moisture simulated by SiBCASA, but the active data seem promising in some aspects. The match between SiBCASA and ASCAT soil moisture is best in the summer months over low vegetation. Nevertheless, ASCAT failed to detect the major droughts occurring between 2007 and 2013. The performance of ASCAT soil moisture seems to be particularly sensitive to ponding, rather than to biomass. The effect on the simulated carbon fluxes is large, 5-10% on annual GPP and TER, tens of percent on local NEE, and 2% on area-integrated NEE, which is the same order of magnitude as the inter-annual variations. Consequently, this study shows that assimilation of satellite-derived soil moisture has potentially large impacts, while at the same time further research is needed to understand under which conditions the satellite-derived soil moisture improves the simulated soil moisture. |
BibTeX:
@article{molen16a,
author = {van der Molen, M. K. and de Jeu, R. A. M. and Wagner, W. and van der Velde, I. R. and Kolari, P. and Kurbatova, J. and Varlagin, A. and Maximov, T. C. and Kononov, A. V. and Ohta, T. and Kotani, A. and Krol, M. C. and Peters, W.},
title = {The effect of assimilating satellite-derived soil moisture data in SiBCASA on simulated carbon fluxes in Boreal Eurasia},
journal = {HYDROLOGY AND EARTH SYSTEM SCIENCES},
year = {2016},
volume = {20},
number = {2},
pages = {605--624},
doi = {10.5194/hess-20-605-2016}
}
|
| Monteil G, Houweling S, Butz A, Guerlet S, Schepers D, Hasekamp O, Frankenberg C, Scheepmaker R, Aben I and Rockmann T ({2013}), "Comparison of CH4 inversions based on 15 months of GOSAT and SCIAMACHY observations", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 27, {2013}. Vol. {118}({20}), pp. 11807-11823. |
| Abstract: [1] Over the past decade the development of Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) retrievals has increased the interest in the use of satellite measurements for studying the global sources and sinks of methane. Meanwhile, measurements are becoming available from the more advanced Greenhouse Gases Observing Satellite (GOSAT). The aim of this study is to investigate the application of GOSAT retrievals to inverse modeling, for which we make use of the TM5-4DVAR inverse modeling framework. Inverse modeling calculations are performed using data from two different retrieval approaches: a full physics and a lightpath proxy ratio method. The performance of these inversions is analyzed in comparison with inversions using SCIAMACHY retrievals and measurements from the National Oceanic and Atmospheric Administration-Earth System Research Laboratory flask-sampling network. In addition, we compare the inversion results against independent surface, aircraft, and total-column measurements. Inversions with GOSAT data show good agreement with surface measurements, whereas for SCIAMACHY a similar performance can only be achieved after significant bias corrections. Some inconsistencies between surface and total-column methane remain in the Southern Hemisphere. However, comparisons with measurements from the Total Column Carbon Observing Network in situ Fourier transform spectrometer network indicate that those may be caused by systematic model errors rather than by shortcomings in the GOSAT retrievals. The global patterns of methane emissions derived from SCIAMACHY (with bias correction) and GOSAT retrievals are in remarkable agreement and allow an increased resolution of tropical emissions. The satellite inversions increase tropical methane emission by 30 to 60 Tg CH4/yr compared to initial a priori estimates, partly counterbalanced by reductions in emissions at midlatitudes to high latitudes. |
BibTeX:
@article{monteil13a,
author = {Monteil, Guillaume and Houweling, Sander and Butz, Andre and Guerlet, Sandrine and Schepers, Dinand and Hasekamp, Otto and Frankenberg, Christian and Scheepmaker, Remco and Aben, Ilse and Rockmann, Thomas},
title = {Comparison of CH4 inversions based on 15 months of GOSAT and SCIAMACHY observations},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2013},
volume = {118},
number = {20},
pages = {11807--11823},
doi = {10.1002/2013JD019760}
}
|
| Montzka SA, Dlugokencky EJ and Butler JH ({2011}), "Non-CO2 greenhouse gases and climate change", NATURE., AUG 4, {2011}. Vol. {476}({7358}), pp. 43-50. |
| Abstract: Earth's climate is warming as a result of anthropogenic emissions of greenhouse gases, particularly carbon dioxide (CO2) from fossil fuel combustion. Anthropogenic emissions of non-CO2 greenhouse gases, such as methane, nitrous oxide and ozone-depleting substances (largely from sources other than fossil fuels), also contribute significantly to warming. Some non-CO2 greenhouse gases have much shorter lifetimes than CO2, so reducing their emissions offers an additional opportunity to lessen future climate change. Although it is clear that sustainably reducing the warming influence of greenhouse gases will be possible only with substantial cuts in emissions of CO2, reducing non-CO2 greenhouse gas emissions would be a relatively quick way of contributing to this goal. |
BibTeX:
@article{montzka11a,
author = {Montzka, S. A. and Dlugokencky, E. J. and Butler, J. H.},
title = {Non-CO2 greenhouse gases and climate change},
journal = {NATURE},
year = {2011},
volume = {476},
number = {7358},
pages = {43--50},
doi = {10.1038/nature10322}
}
|
| Montzka S, Reimann S, O'Doherty S, Engel A, Krüger K and Sturges W (2011), "Ozone-depleting substances (ODSs) and related chemicals" World Meteorological Organization. |
BibTeX:
@book{montzka11b,
author = {Montzka, S and Reimann, SCLA and O'Doherty, S and Engel, A and Krüger, Kirstin and Sturges, WT},
title = {Ozone-depleting substances (ODSs) and related chemicals},
publisher = {World Meteorological Organization},
year = {2011},
url = {http://oceanrep.geomar.de/10405/2/03-Chapter_1.pdf}
}
|
| Moore III B, Crowell SMR, Rayner PJ, Kumer J, O'Dell CW, O'Brien D, Utembe S, Polonsky I, Schimel D and Lemen J ({2018}), "The Potential of the Geostationary Carbon Cycle Observatory (GeoCarb) to Provide Multi-scale Constraints on the Carbon Cycle in the Americas", FRONTIERS IN ENVIRONMENTAL SCIENCE., OCT 17, {2018}. Vol. {6} |
| Abstract: The second NASA Earth Venture Mission, Geostationary Carbon Cycle Observatory (GeoCarb), will provide measurements of atmospheric carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and solar-induced fluorescence (SIF) from Geostationary Orbit (GEO). The GeoCarb mission will deliver daily maps of column concentrations of CO2, CH4, and CO over the observed landmasses in the Americas at a spatial resolution of roughly 10 x 10 km. Persistent measurements of CO2, CH4, CO, and SIF will contribute significantly to resolving carbon emissions and illuminating biotic processes at urban to continental scales, which will allow the improvement of modeled biogeochemical processes in Earth System Models as well as monitor the response of the biosphere to disturbance. This is essential to improve understanding of the Carbon-Climate connection. In this paper, we introduce the instrument and the GeoCarb Mission, and we demonstrate the potential scientific contribution of the mission through a series of CO2 and CH4 simulation experiments. We find that GeoCarb will be able to constrain emissions at urban to continental spatial scales on weekly to annual time scales. The GeoCarb mission particularly builds upon the Orbiting Carbon Obserevatory-2 (OCO-2), which is flying in Low Earth Orbit. |
BibTeX:
@article{moore18a,
author = {Moore, III, Berrien and Crowell, Sean M. R. and Rayner, Peter J. and Kumer, Jack and O'Dell, Christopher W. and O'Brien, Denis and Utembe, Steven and Polonsky, Igor and Schimel, David and Lemen, James},
title = {The Potential of the Geostationary Carbon Cycle Observatory (GeoCarb) to Provide Multi-scale Constraints on the Carbon Cycle in the Americas},
journal = {FRONTIERS IN ENVIRONMENTAL SCIENCE},
year = {2018},
volume = {6},
doi = {{10.3389/fenvs.2018.00109}}
}
|
| Moreira DS, Freitas SR, Bonatti JP, Mercado LM, Rosario NME, Longo KM, Miller JB, Gloor M and Gatti LV ({2013}), "Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO2 budget in South America", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {6}({4}), pp. 1243-1259. |
| Abstract: This article presents the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. This new numerical system is denominated JULES-CCATT-BRAMS. We demonstrate the performance of this new model system in relation to several meteorological variables and the CO2 mixing ratio over a large part of South America, focusing on the Amazon basin. The evaluation was conducted for two time periods, the wet (March) and dry (September) seasons of 2010. The model errors were calculated in relation to meteorological observations at conventional stations in airports and automatic stations. In addition, CO2 mixing ratios in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with observations obtained with airborne instruments. The results of this study show that the JULES-CCATT-BRAMS modeling system provided a significant gain in performance for the considered atmospheric fields relative to those simulated by the LEAF (version 3) surface model originally employed by CCATT-BRAMS. In addition, the new system significantly increases the ability to simulate processes involving air-surface interactions, due to the ability of JULES to simulate photosynthesis, respiration and dynamic vegetation, among other processes. We also discuss a wide range of numerical studies involving coupled atmospheric, land surface and chemistry processes that could be done with the system introduced here. Thus, this work presents to the scientific community a free modeling tool, with good performance in comparison with observational data and reanalysis model data, at least for the region and time period discussed here. Therefore, in principle, this model is able to produce atmospheric hindcast/forecast simulations at different spatial resolutions for any time period and any region of the globe. |
BibTeX:
@article{moreira13a,
author = {Moreira, D. S. and Freitas, S. R. and Bonatti, J. P. and Mercado, L. M. and Rosario, N. M. E. and Longo, K. M. and Miller, J. B. and Gloor, M. and Gatti, L. V.},
title = {Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO2 budget in South America},
journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
year = {2013},
volume = {6},
number = {4},
pages = {1243--1259},
doi = {10.5194/gmd-6-1243-2013}
}
|
| Moreira DS, Longo KM, Freitas SR, Yamasoe MA, Mercado LM, Rosario NE, Gloor E, Viana RSM, Miller JB, Gatti LV, Wiedemann KT, Domingues LKG and Correia CCS ({2017}), "Modeling the radiative effects of biomass burning aerosols on carbon fluxes in the Amazon region", ATMOSPHERIC CHEMISTRY AND PHYSICS., DEC 12, {2017}. Vol. {17}({23}), pp. 14785-14810. |
| Abstract: Every year, a dense smoke haze covers a large portion of South America originating from fires in the Amazon Basin and central parts of Brazil during the dry biomass burning season between August and October. Over a large portion of South America, the average aerosol optical depth at 550 nm exceeds 1.0 during the fire season, while the background value during the rainy season is below 0.2. Biomass burning aerosol particles increase scattering and absorption of the incident solar radiation. The regional-scale aerosol layer reduces the amount of solar energy reaching the surface, cools the near-surface air, and increases the diffuse radiation fraction over a large disturbed area of the Amazon rainforest. These factors affect the energy and CO2 fluxes at the surface. In this work, we applied a fully integrated at-mospheric model to assess the impact of biomass burning aerosols in CO2 fluxes in the Amazon region during 2010. We address the effects of the attenuation of global solar radiation and the enhancement of the diffuse solar radiation flux inside the vegetation canopy. Our results indicate that biomass burning aerosols led to increases of about 27% in the gross primary productivity of Amazonia and 10% in plant respiration as well as a decline in soil respiration of 3%. Consequently, in our model Amazonia became a net carbon sink; net ecosystem exchange during September 2010 dropped from +101 to -104 TgC when the aerosol effects are considered, mainly due to the aerosol diffuse radiation effect. For the forest biome, our results point to a dominance of the diffuse radiation effect on CO2 fluxes, reaching a balance of 50-50% between the diffuse and direct aerosol effects for high aerosol loads. For C3 grasses and savanna (cerrado), as expected, the contribution of the diffuse radiation effect is much lower, tending to zero with the increase in aerosol load. Taking all biomes together, our model shows the Amazon during the dry season, in the presence of high biomass burning aerosol loads, changing from being a source to being a sink of CO2 to the atmosphere. |
BibTeX:
@article{moreira17a,
author = {Moreira, Demerval S. and Longo, Karla M. and Freitas, Saulo R. and Yamasoe, Marcia A. and Mercado, Lina M. and Rosario, Nilton E. and Gloor, Emauel and Viana, Rosane S. M. and Miller, John B. and Gatti, Luciana V. and Wiedemann, Kenia T. and Domingues, Lucas K. G. and Correia, Caio C. S.},
title = {Modeling the radiative effects of biomass burning aerosols on carbon fluxes in the Amazon region},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {23},
pages = {14785--14810},
doi = {10.5194/acp-17-14785-2017}
}
|
| Moro S, Danicic A, Alic N, Usechak NG and Radic S ({2011}), "Widely-tunable parametric short-wave infrared transmitter for CO2 trace detection", OPTICS EXPRESS., APR 25, {2011}. Vol. {19}({9}), pp. 8173-8178. |
| Abstract: An all-fiber, tunable, short-wave infrared transmitter is demonstrated using efficient four-wave mixing in conventional L and O bands. To realize this source a highly-nonlinear fiber, exhibiting low bend loss over the short-wave infrared spectral band, is employed because of its advantageous properties as a nonlinear mixing medium. The transmitter was subsequently exploited to probe and detect trace levels of carbon dioxide in the 2051-nm spectral region where its beam properties, tunability, narrow linewidth, and stability all coalesce to permit this application. This work indicates this transmitter can serve as a robust source for sensing carbon dioxide and other trace gasses in the short-wave infrared spectral region and should therefore play an important role in future applications. (C) 2011 Optical Society of America |
BibTeX:
@article{moro11a,
author = {Moro, Slaven and Danicic, Aleksandar and Alic, Nikola and Usechak, Nicholas G. and Radic, Stojan},
title = {Widely-tunable parametric short-wave infrared transmitter for CO2 trace detection},
journal = {OPTICS EXPRESS},
year = {2011},
volume = {19},
number = {9},
pages = {8173--8178},
doi = {10.1364/OE.19.008173}
}
|
| Moro S (2011), "Parametrically-aided sensing in the short-wave infrared frequency band and beyond". Thesis at: University of California San Diego. |
BibTeX:
@phdthesis{moro11b,
author = {Slaven Moro},
title = {Parametrically-aided sensing in the short-wave infrared frequency band and beyond},
school = {University of California San Diego},
year = {2011},
url = {http://search.proquest.com/openview/09a727bd0d87d88df6a4f2d824b3521b/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Mu M, Randerson JT, van der Werf GR, Giglio L, Kasibhatla P, Morton D, Collatz GJ, DeFries RS, Hyer EJ, Prins EM, Griffith DWT, Wunch D, Toon GC, Sherlock V and Wennberg PO ({2011}), "Daily and 3-hourly variability in global fire emissions and consequences for atmospheric model predictions of carbon monoxide", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 24, {2011}. Vol. {116} |
| Abstract: Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic-and diurnal-scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3). We disaggregated monthly GFED3 emissions during 2003-2009 to a daily time step using Moderate Resolution Imaging Spectroradiometer (MODIS)-derived measurements of active fires from Terra and Aqua satellites. In parallel, mean diurnal cycles were constructed from Geostationary Operational Environmental Satellite (GOES) Wildfire Automated Biomass Burning Algorithm (WFABBA) active fire observations. Daily variability in fires varied considerably across different biomes, with short but intense periods of daily emissions in boreal ecosystems and lower intensity (but more continuous) periods of burning in savannas. These patterns were consistent with earlier field and modeling work characterizing fire behavior dynamics in different ecosystems. On diurnal timescales, our analysis of the GOES WFABBA active fires indicated that fires in savannas, grasslands, and croplands occurred earlier in the day as compared to fires in nearby forests. Comparison with Total Carbon Column Observing Network (TCCON) and Measurements of Pollution in the Troposphere (MOPITT) column CO observations provided evidence that including daily variability in emissions moderately improved atmospheric model simulations, particularly during the fire season and near regions with high levels of biomass burning. The high temporal resolution estimates of fire emissions developed here may ultimately reduce uncertainties related to fire contributions to atmospheric trace gases and aerosols. Important future directions include reconciling top-down and bottom up estimates of fire radiative power and integrating burned area and active fire time series from multiple satellite sensors to improve daily emissions estimates. |
BibTeX:
@article{mu11a,
author = {Mu, M. and Randerson, J. T. and van der Werf, G. R. and Giglio, L. and Kasibhatla, P. and Morton, D. and Collatz, G. J. and DeFries, R. S. and Hyer, E. J. and Prins, E. M. and Griffith, D. W. T. and Wunch, D. and Toon, G. C. and Sherlock, V. and Wennberg, P. O.},
title = {Daily and 3-hourly variability in global fire emissions and consequences for atmospheric model predictions of carbon monoxide},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2011JD016245}
}
|
| Muelleman A, Schell J, Glazer S and Glaser R (2016), "Thermochemistry of a Biomimetic and Rubisco-Inspired CO2 Capture System from Air", C. Vol. 2(3) |
BibTeX:
@article{muelleman16a,
author = {Muelleman, Andrew and Schell, Joseph and Glazer, Spencer and Glaser, Rainer},
title = {Thermochemistry of a Biomimetic and Rubisco-Inspired CO2 Capture System from Air},
journal = {C},
year = {2016},
volume = {2},
number = {3},
url = {http://www.mdpi.com/2311-5629/2/3/18/htm}
}
|
| Mueller KL, Gourdji SM and Michalak AM ({2008}), "Global monthly averaged CO2 fluxes recovered using a geostatistical inverse modeling approach: 1. Results using atmospheric measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 12, {2008}. Vol. {113}({D21}) |
| Abstract: This study presents monthly CO2 fluxes from 1997 to 2001 at a 3.75 degrees latitude x 5 degrees longitude resolution, inferred using a geostatistical inverse modeling approach. The approach focuses on quantifying the information content of measurements from the NOAA-ESRL cooperative air sampling network with regard to the global CO2 budget at different spatial and temporal scales. The geostatistical approach avoids the use of explicit prior flux estimates that have formed the basis of previous synthesis Bayesian inversions and does not prescribe spatial patterns of flux for large, aggregated regions. Instead, the method relies strongly on the atmospheric measurements and the inferred spatial autocorrelation of the fluxes to estimate sources and sinks and their associated uncertainties at the resolution of the atmospheric transport model. Results show that grid-scale estimates exhibit high uncertainty and relatively little small-scale variability, but generally reflect reasonable fluxes in areas that are relatively well constrained by measurements. The aggregated continental-scale fluxes are better constrained, and estimates are consistent with results from previous synthesis Bayesian inversion studies for many regions. Observed differences at the continental scale are primarily attributable to the choice of a priori assumptions in the current work relative to those in other synthesis Bayesian studies. Overall, the results indicate that the geostatistical inverse modeling approach is able to estimate global fluxes using the limited atmospheric measurement network without relying on assumptions about a priori estimates of the flux distribution. As such, the method provides a means of isolating the information content of the atmospheric measurements, and thus serves as a valuable tool for reconciling top-down and bottom-up estimates of CO2 flux variability. |
BibTeX:
@article{mueller08a,
author = {Mueller, Kim L. and Gourdji, Sharon M. and Michalak, Anna M.},
title = {Global monthly averaged CO2 fluxes recovered using a geostatistical inverse modeling approach: 1. Results using atmospheric measurements},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2008},
volume = {113},
number = {D21},
doi = {10.1029/2007JD009734}
}
|
| Mueller KL (2011), "A data-driven multi-scale statistical investigation of regional sources and sinks to improve knowledge of terrestrial carbon cycling". Thesis at: University of Michigan. |
BibTeX:
@phdthesis{mueller11a,
author = {Mueller, Kimberly L},
title = {A data-driven multi-scale statistical investigation of regional sources and sinks to improve knowledge of terrestrial carbon cycling},
school = {University of Michigan},
year = {2011},
url = {http://search.proquest.com/openview/df727968d2cc116d449bf05fe1596bb9/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Mueller K, Yadav V, Lopez-Coto I, Karion A, Gourdji S, Martin C and Whetstone J ({2018}), "Siting Background Towers to Characterize Incoming Air for Urban Greenhouse Gas Estimation: A Case Study in the Washington, DC/Baltimore Area", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 16, {2018}. Vol. {123}({5}), pp. {2910-2926}. |
| Abstract: There is increased interest in understanding urban greenhouse gas (GHG) emissions. To accurately estimate city emissions, the influence of extraurban fluxes must first be removed from urban greenhouse gas (GHG) observations. This is especially true for regions, such as the U.S. Northeastern Corridor-Baltimore/Washington, DC (NEC-B/W), downwind of large fluxes. To help site background towers for the NEC-B/W, we use a coupled Bayesian Information Criteria and geostatistical regression approach to help site four background locations that best explain CO2 variability due to extraurban fluxes modeled at 12 urban towers. The synthetic experiment uses an atmospheric transport and dispersion model coupled with two different flux inventories to create modeled observations and evaluate 15 candidate towers located along the urban domain for February and July 2013. The analysis shows that the average ratios of extraurban inflow to total modeled enhancements at urban towers are 21% to 36% in February and 31% to 43% in July. In July, the incoming air dominates the total variability of synthetic enhancements at the urban towers (R-2=0.58). Modeled observations from the selected background towers generally capture the variability in the synthetic CO2 enhancements at urban towers (R-2=0.75, root-mean-square error (RMSE)=3.64ppm; R-2=0.43, RMSE=4.96ppm for February and July). However, errors associated with representing background air can be up to 10ppm for any given observation even with an optimal background tower configuration. More sophisticated methods may be necessary to represent background air to accurately estimate urban GHG emissions. |
BibTeX:
@article{mueller18a,
author = {Mueller, K. and Yadav, V. and Lopez-Coto, I. and Karion, A. and Gourdji, S. and Martin, C. and Whetstone, J.},
title = {Siting Background Towers to Characterize Incoming Air for Urban Greenhouse Gas Estimation: A Case Study in the Washington, DC/Baltimore Area},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2018},
volume = {123},
number = {5},
pages = {2910-2926},
doi = {{10.1002/2017JD027364}}
}
|
| Nalini K, Uma K, Sijikumar S, Tiwari YK and Ramachandran R (2018), "Satellite- and ground-based measurements of CO2 over the Indian region: its seasonal dependencies, spatial variability, and model estimates", INTERNATIONAL JOURNAL OF REMOTE SENSING., JUN, 2018. Vol. 39(22), pp. 7881-7900. |
BibTeX:
@article{nalini18a,
author = {Nalini, K. and Uma, K.N. and Sijikumar, S. and Tiwari, Yogesh K. and Ramachandran, Radhika},
title = {Satellite- and ground-based measurements of CO2 over the Indian region: its seasonal dependencies, spatial variability, and model estimates},
journal = {INTERNATIONAL JOURNAL OF REMOTE SENSING},
year = {2018},
volume = {39},
number = {22},
pages = {7881-7900},
url = {https://www.tandfonline.com/doi/abs/10.1080/01431161.2018.1479787}
}
|
| Nassar R, Jones DBA, Kulawik SS, Worden JR, Bowman KW, Andres RJ, Suntharalingam P, Chen JM, Brenninkmeijer CAM, Schuck TJ, Conway TJ and Worthy DE ({2011}), "Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({12}), pp. 6029-6047. |
| Abstract: We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES) and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40 degrees S-40 degrees N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion for the year 2006 yields -1.13 +/- 0.21 PgC for the global ocean, -2.77 +/- 0.20 PgC for the global land biosphere and -3.90 +/- 0.29 PgC for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion). These global ocean and global land fluxes are shown to be near the median of the broad range of values from other inversion results for 2006. To achieve these results, a bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for flux inversions. |
BibTeX:
@article{nassar11a,
author = {Nassar, R. and Jones, D. B. A. and Kulawik, S. S. and Worden, J. R. and Bowman, K. W. and Andres, R. J. and Suntharalingam, P. and Chen, J. M. and Brenninkmeijer, C. A. M. and Schuck, T. J. and Conway, T. J. and Worthy, D. E.},
title = {Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2011},
volume = {11},
number = {12},
pages = {6029--6047},
doi = {10.5194/acp-11-6029-2011}
}
|
| Nassar R, Napier-Linton L, Gurney KR, Andres RJ, Oda T, Vogel FR and Deng F ({2013}), "Improving the temporal and spatial distribution of CO2 emissions from global fossil fuel emission data sets", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 27, {2013}. Vol. {118}({2}), pp. 917-933. |
| Abstract: Through an analysis of multiple global fossil fuel CO2 emission data sets, Vulcan emission data for the United States, Canada's National Inventory Report, and NO2 variability based on satellite observations, we derive scale factors that can be applied to global emission data sets to represent weekly and diurnal CO2 emission variability. This is important for inverse modeling and data assimilation of CO2, which use in situ or satellite measurements subject to variability on these time scales. Model simulations applying the weekly and diurnal scaling show that, although the impacts are minor far away from sources, surface atmospheric CO2 is perturbed by up to 1.5-8 ppm and column-averaged CO2 is perturbed by 0.1-0.5 ppm over some major cities, suggesting the magnitude of model biases for urban areas when these modes of temporal variability are not represented. In addition, we also derive scale factors to account for the large per capita differences in CO2 emissions between Canadian provinces that arise from differences in per capita energy use and the proportion of energy generated by methods that do not emit CO2, which are not accounted for in population-based global emission data sets. The resulting products of these analyses are global 0.25 degrees x 0.25 degrees gridded scale factor maps that can be applied to global fossil fuel CO2 emission data sets to represent weekly and diurnal variability and 1 degrees x 1 degrees scale factor maps to redistribute spatially emissions from two common global data sets to account for differences in per capita emissions within Canada. |
BibTeX:
@article{nassar13a,
author = {Nassar, Ray and Napier-Linton, Louis and Gurney, Kevin R. and Andres, Robert J. and Oda, Tomohiro and Vogel, Felix R. and Deng, Feng},
title = {Improving the temporal and spatial distribution of CO2 emissions from global fossil fuel emission data sets},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2013},
volume = {118},
number = {2},
pages = {917--933},
doi = {10.1029/2012JD018196}
}
|
| Nassar R, Sioris CE, Jones DBA and McConnell JC ({2014}), "Satellite observations of CO2 from a highly elliptical orbit for studies of the Arctic and boreal carbon cycle", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 16, {2014}. Vol. {119}({5}), pp. 2654-2673. |
| Abstract: Here we report on an observing system simulation experiment (OSSE) to compare the efficacy of near-infrared satellite observations of CO2 from a highly elliptical orbit (HEO) and a low Earth orbit (LEO), for constraining Arctic and boreal CO2 sources and sinks. The carbon cycle at these latitudes (similar to 50-90 degrees N) is primarily driven by the boreal forests, but increasing anthropogenic activity and the effects of climate change such as thawing of permafrost throughout this region could also have an important role in the coming years. A HEO enables quasi-geostationary observations of Earth's northern high latitudes, which are not observed from a geostationary orbit. The orbit and observing characteristics for the HEO mission are based on the Weather, Climate and Air quality (WCA) concept proposed for the Polar Communications and Weather (PCW) mission, while those for the LEO mission are based on the Greenhouse gases Observing Satellite (GOSAT). Two WCA instrument configurations were investigated. Adopting the Optimal configuration yielded an observation data set that gave annual Arctic and boreal regional terrestrial biospheric CO2 flux uncertainties an average of 30% lower than those from GOSAT, while a smaller instrument configuration resulted in uncertainties averaging 20% lower than those from GOSAT. For either WCA instrument configuration, much greater reductions in uncertainty occur for spring, summer, and autumn than for winter, with Optimal flux uncertainties for June-August nearly 50% lower than from GOSAT. These findings demonstrate that CO2 observations from HEO offer significant advantages over LEO for constraining CO2 fluxes from the Arctic and boreal regions. Key Points satellites can improve high-latitude coverage CO2 from GOSAT and a HEO mission constraining Arctic and boreal CO2 fluxes |
BibTeX:
@article{nassar14a,
author = {Nassar, Ray and Sioris, Chris E. and Jones, Dylan B. A. and McConnell, John C.},
title = {Satellite observations of CO2 from a highly elliptical orbit for studies of the Arctic and boreal carbon cycle},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2014},
volume = {119},
number = {5},
pages = {2654--2673},
doi = {10.1002/2013JD020337}
}
|
| Negra C, Sweedo CC, Cavender-Bares K and O'Malley R ({2008}), "Indicators of carbon storage in US ecosystems: Baseline for terrestrial carbon", JOURNAL OF ENVIRONMENTAL QUALITY., JUL-AUG, {2008}. Vol. {37}({4}), pp. 1376-1382. |
| Abstract: Policymakers, program managers, and landowners need information about net terrestrial carbon sequestration in forests, croplands, grasslands, and shrublands to understand the cumulative effects of carbon trading programs, expanding biofuels production, and changing environmental conditions in addition to agricultural and forestry uses. Objective information systems that establish credible baselines and track changes in carbon storage can provide the accountability needed for carbon trading programs to achieve durable carbon sequestration and for biofuels initiatives to reduce net greenhouse gas emissions. A multi-sector stakeholder design process was used to produce a new indicator for the 2008 State of the Nation's Ecosystems report that presents metrics of carbon storage for major ecosystem types, specifically change in the amount of carbon gained or lost over time and the amount of carbon stored per unit area (carbon density). These metrics have been developed for national scale use, but are suitable for adaptation to multiple scales such as individual farm and forest parcels, carbon offset markets and integrated national and international assessments. To acquire the data necessary for a complete understanding of how much, and where, carbon is gained or lost by U.S. ecosystems, expansion and integration of monitoring programs will be required. |
BibTeX:
@article{negra08a,
author = {Negra, Christine and Sweedo, Caroline Cremer and Cavender-Bares, Kent and O'Malley, Robin},
title = {Indicators of carbon storage in US ecosystems: Baseline for terrestrial carbon},
journal = {JOURNAL OF ENVIRONMENTAL QUALITY},
year = {2008},
volume = {37},
number = {4},
pages = {1376--1382},
note = {4th USDA Greenhouse Gas Symposium on Positioning Agriculture and Forestry to Meet the Challenges of Climate Change, Baltimore, MD, FEB 06-08, 2007},
doi = {10.2134/jeq2007.0290}
}
|
| Nelson RR, O'Dell CW, Taylor TE, Mandrake L and Smyth M ({2016}), "The potential of clear-sky carbon dioxide satellite retrievals", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({4}), pp. 1671-1684. |
| Abstract: Since the launch of the Greenhouse Gases Observing Satellite (GOSAT) in 2009, retrieval algorithms designed to infer the column-averaged dry-air mole fraction of carbon dioxide (X-CO2) from hyperspectral near-infrared observations of reflected sunlight have been greatly improved. They now generally include the scattering effects of clouds and aerosols, as early work found that absorption-only retrievals, which neglected these effects, often incurred unacceptably large errors, even for scenes with optically thin cloud or aerosol layers. However, these ``full-physics'' retrievals tend to be computationally expensive and may incur biases from trying to deduce the properties of clouds and aerosols when there are none present. Additionally, algorithms are now available that can quickly and effectively identify and remove most scenes in which cloud or aerosol scattering plays a significant role. In this work, we test the hypothesis that non-scattering, or ``clear-sky'', retrievals may perform as well as full-physics retrievals for sufficiently clear scenes. Clear-sky retrievals could potentially avoid errors and biases brought about by trying to infer properties of clouds and aerosols when none are present. Clear-sky retrievals are also desirable because they are orders of magnitude faster than full-physics retrievals. Here we use a simplified version of the Atmospheric Carbon Observations from Space (ACOS) X-CO2 retrieval algorithm that does not include the scattering and absorption effects of clouds or aerosols. It was found that for simulated Orbiting Carbon Observatory-2 (OCO-2) measurements, the clear-sky retrieval had errors comparable to those of the full-physics retrieval. For real GOSAT data, the clear-sky retrieval had errors 0-20% larger than the full-physics retrieval over land and errors roughly 20-35% larger over ocean, depending on filtration level. In general, the clear-sky retrieval had X-CO2 root-mean-square errors (RMSEs) of less than 2.0 ppm, relative to Total Carbon Column Observing Network (TCCON) measurements and a suite of CO2 models, when adequately filtered through the use of a custom genetic algorithm filtering system. These results imply that non-scattering X-CO2 retrievals are potentially more useful than previous literature suggests, as the filtering methods we employ are able to remove measurements in which scattering can cause significant errors. Additionally, the computational benefits of non-scattering retrievals means they may be useful for certain applications that require large amounts of data but have less stringent error requirements. |
BibTeX:
@article{nelson16a,
author = {Nelson, Robert R. and O'Dell, Christopher W. and Taylor, Thomas E. and Mandrake, Lukas and Smyth, Mike},
title = {The potential of clear-sky carbon dioxide satellite retrievals},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2016},
volume = {9},
number = {4},
pages = {1671--1684},
doi = {10.5194/amt-9-1671-2016}
}
|
| Nelson KS (2016), "Biofilm response to ocean acidification and the effects on serpulid polychaete settlement". Thesis at: University of Otago. |
BibTeX:
@mastersthesis{nelson16b,
author = {Nelson, Kathryn Sarah},
title = {Biofilm response to ocean acidification and the effects on serpulid polychaete settlement},
school = {University of Otago},
year = {2016},
url = {https://otago.ourarchive.ac.nz/handle/10523/6783}
}
|
| Nevison C, Andrews A, Thoning K, Dlugokencky E, Sweeney C, Miller S, Saikawa E, Benmergui J, Fischer M, Mountain M and Nehrkorn T ({2018}), "Nitrous Oxide Emissions Estimated With the CarbonTracker-Lagrange North American Regional Inversion Framework", GLOBAL BIOGEOCHEMICAL CYCLES., MAR, {2018}. Vol. {32}({3}), pp. {463-485}. |
| Abstract: North American nitrous oxide (N2O) emissions of 1.60.3TgN/yr over 2008-2014 are estimated using the CarbonTracker-Lagrange regional inversion framework. The estimated N2O emissions are largely consistent with the EDGAR (Emission Database for Global Atmospheric Research) global inventory and with the results of global atmospheric inversions but offer more spatial and temporal detail over North America. Emissions are strongest from the Midwestern Corn/Soybean Belt, which accounts for nearly one third of the total North American N2O source. The emissions are maximum in spring/early summer, consistent with a nitrogen fertilizer-driven source, and also show a late winter spike suggestive of freeze-thaw effects. Interannual variability in emissions across the primary months of fertilizer application is positively correlated to mean precipitation. The estimated N2O flux from the Midwestern Corn/Soybean Belt and the more northerly United States/Canadian wheat belt corresponds to 4.2-4.6% and 2.2-3.0 respectively, of total synthetic+organic N fertilizer applied to those regions. Consideration of nonagricultural sources and additional N inputs from soybean N-2 fixation could reduce the N2O yield from the Midwestern Corn/Soybean Belt to similar to 2.2-2.4% of total N inputs. Plain Language Summary Emissions of nitrous oxide (N2O) emissions over North America were estimated based on an inverse model, in which atmospheric concentrations of N2O measured at 40 different National Oceanographic Atmospheric Administration (NOAA) sites were inverted to estimate surface sources. The estimated N2O emissions showed a clear hot spot in the Midwestern corn/soybean belt, which accounted for nearly one third (0.48 0.02 x 10(12)gN/yr) of the total North American N2O source (1.6 0.3x10(12)gN/yr). The emissions were maximum in spring and early summer, consistent with the timing of nitrogen fertilizer application to the corn/soybean belt. Interannual variability across 2007-2015 in the inferred emissions suggested that climate may interact with fertilizer to influence N2O source strength, with the warm drought year 2012 showing substantially lower emissions than other years. |
BibTeX:
@article{nevison18a,
author = {Nevison, Cynthia and Andrews, Arlyn and Thoning, Kirk and Dlugokencky, Ed and Sweeney, Colm and Miller, Scot and Saikawa, Eri and Benmergui, Joshua and Fischer, Marc and Mountain, Marikate and Nehrkorn, Thomas},
title = {Nitrous Oxide Emissions Estimated With the CarbonTracker-Lagrange North American Regional Inversion Framework},
journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
year = {2018},
volume = {32},
number = {3},
pages = {463-485},
doi = {{10.1002/2017GB005759}}
}
|
| Nguyen H, Osterman G, Wunch D, O'Dell C, Mandrake L, Wennberg P, Fisher B and Castano R ({2014}), "A method for colocating satellite X-CO2 data to ground-based data and its application to ACOS-GOSAT and TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {7}({8}), pp. 2631-2644. |
| Abstract: Satellite measurements are often compared with higher-precision ground-based measurements as part of validation efforts. The satellite soundings are rarely perfectly coincident in space and time with the ground-based measurements, so a colocation methodology is needed to aggregate ``nearby'' soundings into what the instrument would have seen at the location and time of interest. We are particularly interested in validation efforts for satellite-retrieved total column carbon dioxide (X-CO2), where X-CO2 data from Greenhouse Gas Observing Satellite (GOSAT) retrievals (ACOS, NIES, RemoteC, PPDF, etc.) or SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIA-MACHY) are often colocated and compared to ground-based column X-CO2 measurement from Total Carbon Column Observing Network (TCCON). Current colocation methodologies for comparing satellite measurements of total column dry-air mole fractions of CO2 (X-CO2) with ground-based measurements typically involve locating and averaging the satellite measurements within a latitudinal, longitudinal, and temporal window. We examine a geostatistical colocation methodology that takes a weighted average of satellite observations depending on the ``distance'' of each observation from a ground-based location of interest. The ``distance'' function that we use is a modified Euclidian distance with respect to latitude, longitude, time, and midtropospheric temperature at 700 hPa. We apply this methodology to X-CO2 retrieved from GOSAT spectra by the ACOS team, cross-validate the results to TCCON X-CO2 ground-based data, and present some comparisons between our methodology and standard existing colocation methods showing that, in general, geostatistical colocation produces smaller mean-squared error. |
BibTeX:
@article{nguyen14a,
author = {Nguyen, H. and Osterman, G. and Wunch, D. and O'Dell, C. and Mandrake, L. and Wennberg, P. and Fisher, B. and Castano, R.},
title = {A method for colocating satellite X-CO2 data to ground-based data and its application to ACOS-GOSAT and TCCON},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2014},
volume = {7},
number = {8},
pages = {2631--2644},
doi = {10.5194/amt-7-2631-2014}
}
|
| Niu S, Luo Y, Fei S, Montagnani L, Bohrer G, Janssens IA, Gielen B, Rambal S, Moors E and Matteucci G ({2011}), "Seasonal hysteresis of net ecosystem exchange in response to temperature change: patterns and causes", GLOBAL CHANGE BIOLOGY., OCT, {2011}. Vol. {17}({10}), pp. 3102-3114. |
| Abstract: Understanding how net ecosystem exchange (NEE) changes with temperature is central to the debate on climate change-carbon cycle feedbacks, but still remains unclear. Here, we used eddy covariance measurements of NEE from 20 FLUXNET sites (203 site-years of data) in mid-and high-latitude forests to investigate the temperature response of NEE. Years were divided into two half thermal years (increasing temperature in spring and decreasing temperature in autumn) using the maximum daily mean temperature. We observed a parabolic-like pattern of NEE in response to temperature change in both the spring and autumn half thermal years. However, at similar temperatures, NEE was considerably depressed during the decreasing temperature season as compared with the increasing temperature season, inducing a counter-clockwise hysteresis pattern in the NEE-temperature relation at most sites. The magnitude of this hysteresis was attributable mostly (68 to gross primary production (GPP) differences but little (8 to ecosystem respiration (ER) differences between the two half thermal years. The main environmental factors contributing to the hysteresis responses of NEE and GPP were daily accumulated radiation. Soil water content (SWC) also contributed to the hysteresis response of GPP but only at some sites. Shorter day length, lower light intensity, lower SWC and reduced photosynthetic capacity may all have contributed to the depressed GPP and net carbon uptake during the decreasing temperature seasons. The resultant hysteresis loop is an important indicator of the existence of limiting factors. As such, the role of radiation, LAI and SWC should be considered when modeling the dynamics of carbon cycling in response to temperature change. |
BibTeX:
@article{niu11a,
author = {Niu, Shuli and Luo, Yiqi and Fei, Shenfeng and Montagnani, Leonardo and Bohrer, Gil and Janssens, Ivan A. and Gielen, Bert and Rambal, Serge and Moors, Eddy and Matteucci, Giorgio},
title = {Seasonal hysteresis of net ecosystem exchange in response to temperature change: patterns and causes},
journal = {GLOBAL CHANGE BIOLOGY},
year = {2011},
volume = {17},
number = {10},
pages = {3102--3114},
doi = {10.1111/j.1365-2486.2011.02459.x}
}
|
| Niwa Y, Machida T, Sawa Y, Matsueda H, Schuck TJ, Brenninkmeijer CAM, Imasu R and Satoh M ({2012}), "Imposing strong constraints on tropical terrestrial CO2 fluxes using passenger aircraft based measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUN 5, {2012}. Vol. {117} |
| Abstract: Because very few measurements of atmospheric carbon dioxide (CO2) are available in the tropics, estimates of surface CO2 fluxes in tropical regions are beset with considerable uncertainties. To improve estimates of tropical terrestrial fluxes, atmospheric CO2 inversion was performed using passenger aircraft based measurements of the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project in addition to the surface measurement data set of GLOBALVIEW-CO2. Regional monthly fluxes at the earth's surface were estimated using the Bayesian synthesis approach focusing on the period 2006-2008 using the Nonhydrostatic Icosahedral Atmospheric Model-based Transport Model (NICAM-TM). By adding the aircraft to the surface data, the posterior flux errors were greatly reduced; specifically, error reductions of up to 64% were found for tropical Asia regions. This strong impact is closely related to efficient vertical transport in the tropics. The optimized surface fluxes using the CONTRAIL data were evaluated by comparing the simulated atmospheric CO2 distributions with independent aircraft measurements of the Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) project. The inversion with the CONTRAIL data yields the global carbon sequestration rates of 2.22 +/- 0.28 Pg C yr(-1) for the terrestrial biosphere and 2.24 +/- 0.27 Pg C yr(-1) for the oceans (the both are adjusted by riverine input of CO2). For the first time the CONTRAIL CO2 measurements were used in an inversion system to identify the areas of greatest impact in terms of reducing flux uncertainties. |
BibTeX:
@article{niwa12a,
author = {Niwa, Yosuke and Machida, Toshinobu and Sawa, Yousuke and Matsueda, Hidekazu and Schuck, Tanja J. and Brenninkmeijer, Carl A. M. and Imasu, Ryoichi and Satoh, Masaki},
title = {Imposing strong constraints on tropical terrestrial CO2 fluxes using passenger aircraft based measurements},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2012},
volume = {117},
doi = {10.1029/2012JD017474}
}
|
| Noel S, Bramstedt K, Hilker M, Liebing P, Plieninger J, Reuter M, Rozanov A, Sioris CE, Bovensmann H and Burrows JP ({2016}), "Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({4}), pp. 1485-1503. |
| Abstract: Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called onion peeling DOAS (ONPD), which combines an onion peeling approach with a weighting function DOAS (differential optical absorption spectroscopy) fit in the spectral region between 1559 and 1671 nm. By use of updated pointing information and optimisation of the data selection as well as of the retrieval approach, the altitude range for reasonable CH4 could be broadened from 20 to 40 km to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles (17-45 km) of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5-10% for CH4 and 2-3% for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002-April 2012) and the latitudinal range between about 50 and 70 degrees N have been derived. Based on these time series, CH4 and CO2 trends have been estimated. CH4 trends above about 20 km are not significantly different from zero and the trend at 17 km is about 3 ppbv year(-1). The derived CO2 trends show a general decrease with altitude with values of about 1.9 ppmv year(-1) at 21 km and about 1.3 ppmv year(-1) at 39 km. These results are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere. |
BibTeX:
@article{noel16a,
author = {Noel, Stefan and Bramstedt, Klaus and Hilker, Michael and Liebing, Patricia and Plieninger, Johannes and Reuter, Max and Rozanov, Alexei and Sioris, Christopher E. and Bovensmann, Heinrich and Burrows, John P.},
title = {Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2016},
volume = {9},
number = {4},
pages = {1485--1503},
doi = {10.5194/amt-9-1485-2016}
}
|
| Novick KA, Ficklin DL, Stoy PC, Williams CA, Bohrer G, Oishi AC, Papuga SA, Blanken PD, Noormets A, Sulman BN, Scott RL, Wang L and Phillips RP ({2016}), "The increasing importance of atmospheric demand for ecosystem water and carbon fluxes", NATURE CLIMATE CHANGE., NOV, {2016}. Vol. {6}({11}), pp. 1023-1027. |
| Abstract: Soil moisture supply and atmospheric demand for water independently limit-and profoundly affect-vegetation productivity and water use during periods of hydrologic stress(1-4). Disentangling the impact of these two drivers on ecosystem carbon and water cycling is difficult because they are often correlated, and experimental tools for manipulating atmospheric demand in the field are lacking. Consequently, the role of atmospheric demand is often not adequately factored into experiments or represented in models(5-7). Here we show that atmospheric demand limits surface conductance and evapotranspiration to a greater extent than soil moisture in many biomes, including mesic forests that are of particular importance to the terrestrial carbon sink(8,9). Further, using projections from ten general circulation models, we show that climate change will increase the importance of atmospheric constraints to carbon and water fluxes in all ecosystems. Consequently, atmospheric demand will become increasingly important for vegetation function, accounting for >70% of growing season limitation to surface conductance in mesic temperate forests. Our results suggest that failure to consider the limiting role of atmospheric demand in experimental designs, simulation models and land management strategies will lead to incorrect projections of ecosystem responses to future climate conditions. |
BibTeX:
@article{novick16a,
author = {Novick, Kimberly A. and Ficklin, Darren L. and Stoy, Paul C. and Williams, Christopher A. and Bohrer, Gil and Oishi, A. Christopher and Papuga, Shirley A. and Blanken, Peter D. and Noormets, Asko and Sulman, Benjamin N. and Scott, Russell L. and Wang, Lixin and Phillips, Richard P.},
title = {The increasing importance of atmospheric demand for ecosystem water and carbon fluxes},
journal = {NATURE CLIMATE CHANGE},
year = {2016},
volume = {6},
number = {11},
pages = {1023--1027},
doi = {10.1038/NCLIMATE3114}
}
|
| Oda T, Maksyutov S and Andres R (2018), "The Open-source Data Inventory for Anthropogenic CO2, version 2016 (ODIAC2016): a global monthly fossil fuel CO2 gridded emissions data product for tracer transport simulations and surface flux inversions", Earth System Science Data., JAN 18, 2018. Vol. {10}({1}), pp. {87-107}. |
| Abstract: The Open-source Data Inventory for Anthropogenic CO2 (ODIAC) is a global high-spatial-resolution gridded emissions data product that distributes carbon dioxide (CO2) emissions from fossil fuel combustion. The emissions spatial distributions are estimated at a 1 x 1 km spatial resolution over land using power plant profiles (emissions intensity and geographical location) and satellite-observed nighttime lights. This paper describes the year 2016 version of the ODIAC emissions data product (ODIAC2016) and presents analyses that help guide data users, especially for atmospheric CO2 tracer transport simulations and flux inversion analysis. Since the original publication in 2011, we have made modifications to our emissions modeling framework in order to deliver a comprehensive global gridded emissions data product. Major changes from the 2011 publication are (1) the use of emissions estimates made by the Carbon Dioxide Information Analysis Center (CDIAC) at the Oak Ridge National Laboratory (ORNL) by fuel type (solid, liquid, gas, cement manufacturing, gas flaring, and international aviation and marine bunkers); (2) the use of multiple spatial emissions proxies by fuel type such as (a) nighttime light data specific to gas flaring and (b) ship/aircraft fleet tracks; and (3) the inclusion of emissions temporal variations. Using global fuel consumption data, we extrapolated the CDIAC emissions estimates for the recent years and produced the ODIAC2016 emissions data product that covers 2000-2015. Our emissions data can be viewed as an extended version of CDIAC gridded emissions data product, which should allow data users to impose global fossil fuel emissions in a more comprehensive manner than the original CDIAC product. Our new emissions modeling framework allows us to produce future versions of the ODIAC emissions data product with a timely update. Such capability has become more significant given the CDIAC/ORNL's shutdown. The ODIAC data product could play an important role in supporting carbon cycle science, especially modeling studies with space-based CO2 data collected in near real time by ongoing carbon observing missions such as the Japanese Greenhouse gases Observing SATellite (GOSAT), NASA's Orbiting Carbon Observatory-2 (OCO-2), and upcoming future missions. The ODIAC emissions data product including the latest version of the ODIAC emissions data (ODIAC2017, 2000-2016) is distributed from http://db.cger.nies.go. jp/dataset/ODIAC/ with a DOI (https://doi.org/10.17595/20170411.001). |
BibTeX:
@article{oda18a,
author = {T Oda and S Maksyutov and RJ Andres},
title = {The Open-source Data Inventory for Anthropogenic CO2, version 2016 (ODIAC2016): a global monthly fossil fuel CO2 gridded emissions data product for tracer transport simulations and surface flux inversions},
journal = {Earth System Science Data},
year = {2018},
volume = {10},
number = {1},
pages = {87-107},
doi = {{10.5194/essd-10-87-2018}}
}
|
| O'Dell CW, Eldering A, Wennberg PO, Crisp D, Gunson MR, Fisher B, Frankenberg C, Kiel M, Lindqvist H, Mandrake L, Merrelli A, Natraj V, Nelson RR, Osterman GB, Payne VH, Taylor TE, Wunch D, Drouin BJ, Oyafuso F, Chang A, McDuffie J, Smyth M, Baker DF, Basu S, Chevallier F, Crowell SMR, Feng L, Palmer PI, Dubey M, Garcia OE, Griffith DWT, Hase F, Iraci LT, Kivi R, Morino I, Notholt J, Ohyama H, Petri C, Roehl CM, Sha MK, Strong K, Sussmann R, Te Y, Uchino O and Velazco VA ({2018}), "Improved retrievals of carbon dioxide from Orbiting Carbon Observatory-2 with the version 8 ACOS algorithm", ATMOSPHERIC MEASUREMENT TECHNIQUES., DEC 11, {2018}. Vol. {11}({12}), pp. {6539-6576}. |
| Abstract: Since September 2014, NASA's Orbiting Carbon Observatory-2 (OCO-2) satellite has been taking measurements of reflected solar spectra and using them to infer atmospheric carbon dioxide levels. This work provides details of the OCO-2 retrieval algorithm, versions 7 and 8, used to derive the column-averaged dry air mole fraction of atmospheric CO2 (X-CO2) for the roughly 100 000 cloud-free measurements recorded by OCO-2 each day. The algorithm is based on the Atmospheric Carbon Observations from Space (ACOS) algorithm which has been applied to observations from the Greenhouse Gases Observing SATellite (GOSAT) since 2009, with modifications necessary for OCO-2. Because high accuracy, better than 0.25 is required in order to accurately infer carbon sources and sinks from X-CO2, significant errors and regional-scale biases in the measurements must be minimized. We discuss efforts to filter out poor-quality measurements, and correct the remaining good-quality measurements to minimize regional-scale biases. Updates to the radiance calibration and retrieval forward model in version 8 have improved many aspects of the retrieved data products. The version 8 data appear to have reduced regional-scale biases overall, and demonstrate a clear improvement over the version 7 data. In particular, error variance with respect to TCCON was reduced by 20% over land and 40% over ocean between versions 7 and 8, and nadir and glint observations over land are now more consistent. While this paper documents the significant improvements in the ACOS algorithm, it will continue to evolve and improve as the CO2 data record continues to expand. |
BibTeX:
@article{odell18a,
author = {O'Dell, Christopher W. and Eldering, Annmarie and Wennberg, Paul O. and Crisp, David and Gunson, Michael R. and Fisher, Brendan and Frankenberg, Christian and Kiel, Matthaus and Lindqvist, Hannakaisa and Mandrake, Lukas and Merrelli, Aronne and Natraj, Vijay and Nelson, Robert R. and Osterman, Gregory B. and Payne, Vivienne H. and Taylor, Thomas E. and Wunch, Debra and Drouin, Brian J. and Oyafuso, Fabiano and Chang, Albert and McDuffie, James and Smyth, Michael and Baker, David F. and Basu, Sourish and Chevallier, Frederic and Crowell, Sean M. R. and Feng, Liang and Palmer, Paul I. and Dubey, Mavendra and Garcia, Omaira E. and Griffith, David W. T. and Hase, Frank and Iraci, Laura T. and Kivi, Rigel and Morino, Isamu and Notholt, Justus and Ohyama, Hirofumi and Petri, Christof and Roehl, Coleen M. and Sha, Mahesh K. and Strong, Kimberly and Sussmann, Ralf and Te, Yao and Uchino, Osamu and Velazco, Voltaire A.},
title = {Improved retrievals of carbon dioxide from Orbiting Carbon Observatory-2 with the version 8 ACOS algorithm},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2018},
volume = {11},
number = {12},
pages = {6539-6576},
doi = {{10.5194/amt-11-6539-2018}}
}
|
| Ogle SM, Davis K, Lauvaux T, Schuh A, Cooley D, West TO, Heath LS, Miles NL, Richardson S, Breidt FJ, Smith JE, McCarty JL, Gurney KR, Tans P and Denning AS ({2015}), "An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO2 concentration data", ENVIRONMENTAL RESEARCH LETTERS., MAR, {2015}. Vol. {10}({3}) |
| Abstract: Verifying national greenhouse gas (GHG) emissions inventories is a critical step to ensure that reported emissions data to the United Nations Framework Convention on Climate Change (UNFCCC) are accurate and representative of a country's contribution to GHG concentrations in the atmosphere. Furthermore, verifying biogenic fluxes provides a check on estimated emissions associated with managing lands for carbon sequestration and other activities, which often have large uncertainties. We report here on the challenges and results associated with a case study using atmospheric measurements of CO2 concentrations and inverse modeling to verify nationally-reported biogenic CO2 emissions. The biogenic CO2 emissions inventory was compiled for the Mid-Continent region of United States based on methods and data used by the US government for reporting to the UNFCCC, along with additional sources and sinks to produce a full carbon balance. The biogenic emissions inventory produced an estimated flux of -408 +/- 136 TgCO(2) for the entire study region, which was not statistically different from the biogenic flux of -478 +/- 146 TgCO(2) that was estimated using the atmospheric CO2 concentration data. At sub-regional scales, the spatial density of atmospheric observations did not appear sufficient to verify emissions in general. However, a difference between the inventory and inversion results was found in one isolated area of West-central Wisconsin. This part of the region is dominated by forestlands, suggesting that further investigation may be warranted into the forest Cstock or harvested wood product data from this portion of the study area. The results suggest that observations of atmospheric CO2 concentration data and inverse modeling could be used to verify biogenic emissions, and provide more confidence in biogenic GHG emissions reporting to the UNFCCC. |
BibTeX:
@article{ogle15a,
author = {Ogle, Stephen M. and Davis, Kenneth and Lauvaux, Thomas and Schuh, Andrew and Cooley, Dan and West, Tristram O. and Heath, Linda S. and Miles, Natasha L. and Richardson, Scott and Breidt, F. Jay and Smith, James E. and McCarty, Jessica L. and Gurney, Kevin R. and Tans, Pieter and Denning, A. Scott},
title = {An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO2 concentration data},
journal = {ENVIRONMENTAL RESEARCH LETTERS},
year = {2015},
volume = {10},
number = {3},
doi = {10.1088/1748-9326/10/3/034012}
}
|
| Palko H (2017), "Exploring Potential Sites for Salinity Gradient Renewable Energy on the North Carolina Coast and Evaluating the Potential Effects of Local Salinity Regime Variation on SAV Communities due to Reverse Electrodialysis Effluent" |
BibTeX:
@phdthesis{palko17a,
author = {Palko, Hannah},
title = {Exploring Potential Sites for Salinity Gradient Renewable Energy on the North Carolina Coast and Evaluating the Potential Effects of Local Salinity Regime Variation on SAV Communities due to Reverse Electrodialysis Effluent},
year = {2017},
url = {http://search.proquest.com/openview/a19725ee830dba965021f7c25ae33a4e/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
|
| Pan Y, Chen JM, Birdsey R, McCullough K, He L and Deng F ({2011}), "Age structure and disturbance legacy of North American forests", BIOGEOSCIENCES. Vol. {8}({3}), pp. 715-732. |
| Abstract: Most forests of the world are recovering from a past disturbance. It is well known that forest disturbances profoundly affect carbon stocks and fluxes in forest ecosystems, yet it has been a great challenge to assess disturbance impacts in estimates of forest carbon budgets. Net sequestration or loss of CO(2) by forests after disturbance follows a predictable pattern with forest recovery. Forest age, which is related to time since disturbance, is a useful surrogate variable for analyses of the impact of disturbance on forest carbon. In this study, we compiled the first continental forest age map of North America by combining forest inventory data, historical fire data, optical satellite data and the dataset from NASA's Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) project. A companion map of the standard deviations for age estimates was developed for quantifying uncertainty. We discuss the significance of the disturbance legacy from the past, as represented by current forest age structure in different regions of the US and Canada, by analyzing the causes of disturbances from land management and nature over centuries and at various scales. We also show how such information can be used with inventory data for analyzing carbon management opportunities. By combining geographic information about forest age with estimated C dynamics by forest type, it is possible to conduct a simple but powerful analysis of the net CO2 uptake by forests, and the potential for increasing (or decreasing) this rate as a result of direct human intervention in the disturbance/age status. Finally, we describe how the forest age data can be used in large-scale carbon modeling, both for land-based biogeochemistry models and atmosphere-based inversion models, in order to improve the spatial accuracy of carbon cycle simulations. |
BibTeX:
@article{pan11a,
author = {Pan, Y. and Chen, J. M. and Birdsey, R. and McCullough, K. and He, L. and Deng, F.},
title = {Age structure and disturbance legacy of North American forests},
journal = {BIOGEOSCIENCES},
year = {2011},
volume = {8},
number = {3},
pages = {715--732},
doi = {10.5194/bg-8-715-2011}
}
|
| Pandey R, Paul V, Sehgal VK, Singh MP and Bandyopadhyay K (2013), "Monitoring of CO2 exchange and carbon pools in vegetation and soil", Indian Journal of Plant Physiology. Vol. 18(2), pp. 98-117. |
BibTeX:
@article{pandey13a,
author = {Pandey, Rakesh and Paul, Vijay and Sehgal, Vinay Kumar and Singh, Madan Pal and Bandyopadhyay, Kalikinkar},
title = {Monitoring of CO2 exchange and carbon pools in vegetation and soil},
journal = {Indian Journal of Plant Physiology},
year = {2013},
volume = {18},
number = {2},
pages = {98--117},
doi = {10.1007/s40502-013-0016-0}
}
|
| Pandey S, Houweling S, Krol M, Aben I and Rockmann T ({2015}), "On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({15}), pp. 8615-8629. |
| Abstract: We present a method for assimilating total column CH4 : CO2 ratio measurements from satellites for inverse modeling of CH4 and CO2 fluxes using the variational approach. Unlike conventional approaches, in which retrieved CH4 : CO2 are multiplied by model-derived total column CO2 and only the resulting CH4 is assimilated, our method assimilates the ratio of CH4 and CO2 directly and is therefore called the ratio method. It is a dual tracer inversion, in which surface fluxes of CH4 and CO2 are optimized simultaneously. The optimization of CO2 fluxes turns the hard constraint of prescribing model-derived CO2 fields into a weak constraint on CO2, which allows us to account for uncertainties in CO2. The method has been successfully tested in a synthetic inversion setup. We show that the ratio method is able to reproduce assumed true CH4 and CO2 fluxes starting from a prior, which is derived by perturbing the true fluxes randomly. We compare the performance of the ratio method with that of the traditional proxy approach and the use of only surface measurements for estimating CH4 fluxes. Our results confirm that the optimized CH4 fluxes are sensitive to the treatment of CO2, and that hard constraints on CO2 may significantly compromise results that are obtained for CH4. We find that the relative performance of ratio and proxy methods have a regional dependence. The ratio method performs better than the proxy method in regions where the CO2 fluxes are most uncertain. However, both ratio and proxy methods perform better than the surface-measurement-only inversion, confirming the potential of spaceborne measurements for accurately determining fluxes of CH4 and other greenhouse gases (GHGs). |
BibTeX:
@article{pandey15a,
author = {Pandey, S. and Houweling, S. and Krol, M. and Aben, I. and Rockmann, T.},
title = {On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2015},
volume = {15},
number = {15},
pages = {8615--8629},
doi = {10.5194/acp-15-8615-2015}
}
|
| Pandey S, Houweling S, Krol M, Aben I, Chevallier F, Dlugokencky EJ, Gatti LV, Gloor E, Miller JB, Detmers R, Machida T and Rockmann T ({2016}), "Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {16}({8}), pp. 5043-5062. |
| Abstract: This study investigates the constraint provided by greenhouse gas measurements from space on surface fluxes. Imperfect knowledge of the light path through the atmosphere, arising from scattering by clouds and aerosols, can create biases in column measurements retrieved from space. To minimize the impact of such biases, ratios of total column retrieved CH4 and CO2 (X-ratio) have been used. We apply the ratio inversion method described in Pandey et al. (2015) to retrievals from the Greenhouse Gases Observing SATellite (GOSAT). The ratio inversion method uses the measured X-ratio as a weak constraint on CO2 fluxes. In contrast, the more common approach of inverting proxy CH4 retrievals (Frankenberg et al., 2005) prescribes atmospheric CO2 fields and optimizes only CH4 fluxes. The TM5-4DVAR (Tracer Transport Model version 5-variational data assimilation system) inverse modeling system is used to simultaneously optimize the fluxes of CH4 and CO2 for 2009 and 2010. The results are compared to proxy inversions using model-derived CO2 mixing ratios (XCO2model) from CarbonTracker and the Monitoring Atmospheric Composition and Climate (MACC) Reanalysis CO2 product. The performance of the inverse models is evaluated using measurements from three aircraft measurement projects. X-ratio and XCO2model are compared with TCCON retrievals to quantify the relative importance of errors in these components of the proxy XCH4 retrieval (XCH4proxy). We find that the retrieval errors in X-ratio (meanaEuro- = aEuro-0.61aEuro- are generally larger than the errors in XCO2model (meanaEuro- = aEuro-0.24 and 0.01aEuro-% for CarbonTracker and MACC, respectively). On the annual timescale, the CH4 fluxes from the different satellite inversions are generally in agreement with each other, suggesting that errors in XCO2model do not limit the overall accuracy of the CH4 flux estimates. On the seasonal timescale, however, larger differences are found due to uncertainties in XCO2model, particularly over Australia and in the tropics. The ratio method stays closer to the a priori CH4 flux in these regions, because it is capable of simultaneously adjusting the CO2 fluxes. Over tropical South America, comparison to independent measurements shows that CO2 fields derived from the ratio method are less realistic than those used in the proxy method. However, the CH4 fluxes are more realistic, because the impact of unaccounted systematic uncertainties is more evenly distributed between CO2 and CH4. The ratio inversion estimates an enhanced CO2 release from tropical South America during the dry season of 2010, which is in accordance with the findings of Gatti et al. (2014) and Van der Laan et al. (2015). The performance of the ratio method is encouraging, because despite the added nonlinearity due to the assimilation of X-ratio and the significant increase in the degree of freedom by optimizing CO2 fluxes, still consistent results are obtained with respect to other CH4 inversions.. |
BibTeX:
@article{pandey16a,
author = {Pandey, Sudhanshu and Houweling, Sander and Krol, Maarten and Aben, Ilse and Chevallier, Frederic and Dlugokencky, Edward J. and Gatti, Luciana V. and Gloor, Emanuel and Miller, John B. and Detmers, Rob and Machida, Toshinobu and Rockmann, Thomas},
title = {Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2016},
volume = {16},
number = {8},
pages = {5043--5062},
doi = {10.5194/acp-16-5043-2016}
}
|
| Pandey S (2017), "Advancing the use of satellites to constrain atmospheric methane fluxes". Thesis at: Utrecht University. |
BibTeX:
@phdthesis{pandey17a,
author = {Pandey, Sudhanshu},
title = {Advancing the use of satellites to constrain atmospheric methane fluxes},
school = {Utrecht University},
year = {2017},
url = {https://dspace.library.uu.nl/handle/1874/345119}
}
|
| Pandeyl R, Paull V, Sehgals V, al Singh MP and Bandyopadhyay K (2013), "CAPACITIES AND UNCERTAINTIES IN MONITORING THE CARBON DIOXIDE FLUXES AND CARBON POOLS AT DIFFERENT SCALES IN TERRESTRIAL …", Physiology of Nutrition and Environmental Stresses on Crop Productivity.
[BibTeX] |
BibTeX:
@article{pandeyl13a,
author = {Pandeyl, Rakesh and Paull, Vijay and Sehgals, Vinay and al Singh, Madan P and Bandyopadhyay, Kalikinkar},
title = {CAPACITIES AND UNCERTAINTIES IN MONITORING THE CARBON DIOXIDE FLUXES AND CARBON POOLS AT DIFFERENT SCALES IN TERRESTRIAL …},
journal = {Physiology of Nutrition and Environmental Stresses on Crop Productivity},
year = {2013}
}
|
| Parazoo NC (2011), "Moist synoptic transport of CO₂ along midlatitude storm tracks, transport uncertainty, and implications for flux estimation". Thesis at: Colorado State University. |
BibTeX:
@phdthesis{parazoo11a,
author = {Parazoo, Nicholas C},
title = {Moist synoptic transport of CO₂ along midlatitude storm tracks, transport uncertainty, and implications for flux estimation},
school = {Colorado State University},
year = {2011},
url = {https://dspace.library.colostate.edu/handle/10217/48164}
}
|
| Parazoo NC, Arneth A, Pugh TAM, Smith B, Steiner N, Luus K, Commane R, Benmergui J, Stofferahn E, Liu J, Roedenbeck C, Kawa R, Euskirchen E, Zona D, Arndt K, Oechel W and Miller C ({2018}), "Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing", GLOBAL CHANGE BIOLOGY., AUG, {2018}. Vol. {24}({8}), pp. {3416-3435}. |
| Abstract: The springtime transition to regional-scale onset of photosynthesis and net ecosystem carbon uptake in boreal and tundra ecosystems are linked to the soil freeze-thaw state. We present evidence from diagnostic and inversion models constrained by satellite fluorescence and airborne CO2 from 2012 to 2014 indicating the timing and magnitude of spring carbon uptake in Alaska correlates with landscape thaw and ecoregion. Landscape thaw in boreal forests typically occurs in late April (DOY 111 +/- 7) with a 29 +/- 6 day lag until photosynthetic onset. North Slope tundra thaws 3weeks later (DOY 133 +/- 5) but experiences only a 20 +/- 5 day lag until photosynthetic onset. These time lag differences reflect efficient cold season adaptation in tundra shrub and the longer dehardening period for boreal evergreens. Despite the short transition from thaw to photosynthetic onset in tundra, synchrony of tundra respiration with snow melt and landscape thaw delays the transition from net carbon loss (at photosynthetic onset) to net uptake by 13 +/- 7 days, thus reducing the tundra net carbon uptake period. Two global CO2 inversions using a CASA-GFED model prior estimate earlier northern high latitude net carbon uptake compared to our regional inversion, which we attribute to (i) early photosynthetic-onset model prior bias, (ii) inverse method (scaling factor+optimization window), and (iii) sparsity of available Alaskan CO2 observations. Another global inversion with zero prior estimates the same timing for net carbon uptake as the regional model but smaller seasonal amplitude. The analysis of Alaskan eddy covariance observations confirms regional scale findings for tundra, but indicates that photosynthesis and net carbon uptake occur up to 1 month earlier in evergreens than captured by models or CO2 inversions, with better correlation to above-freezing air temperature than date of primary thaw. Further collection and analysis of boreal evergreen species over multiple years and at additional subarctic flux towers are critically needed. |
BibTeX:
@article{parazoo18a,
author = {Parazoo, Nicholas C. and Arneth, Almut and Pugh, Thomas A. M. and Smith, Ben and Steiner, Nicholas and Luus, Kristina and Commane, Roisin and Benmergui, Josh and Stofferahn, Eric and Liu, Junjie and Roedenbeck, Christian and Kawa, Randy and Euskirchen, Eugenie and Zona, Donatella and Arndt, Kyle and Oechel, Walt and Miller, Charles},
title = {Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing},
journal = {GLOBAL CHANGE BIOLOGY},
year = {2018},
volume = {24},
number = {8},
pages = {3416-3435},
doi = {{10.1111/gcb.14283}}
}
|
| Park J ({2011}), "EVIDENCE FOR OCEANIC CONTROL OF INTERANNUAL CARBON CYCLE FEEDBACKS", AMERICAN JOURNAL OF SCIENCE., JUN, {2011}. Vol. {311}({6}), pp. 485-516. |
| Abstract: Large-scale carbon-cycle feedbacks within Earth's climate system can be inferred from the statistical correlation of atmospheric CO2 and other climate observations. These statistical relationships can serve as validation targets for global carbon-cycle models. Fourier-transform coherence between atmospheric CO2 measured at Mauna Loa, Hawaii, and Hadley Centre global-average temperatures changed in the late 20th century at interannual frequencies, from a 6-month time lag to a 90 phase lag that scaled CO2 fluctuations to a time-integral of the global-average temperature anomaly. Wavelet coherence estimates argue that this change occurred with a recognized ocean-circulation climate transition during the late 1970s. General features of these CO2-temperature correlations are confirmed using global-average temperature from other sources and atmospheric CO2 measured at other locations, though only the Mauna Loa CO2 record is long enough to resolve well the coherence properties before the 1970s transition. The CO2-coherence phase for the global-average surface-air temperature time series from NASA-GISS and the lower-troposphere temperature series from the MSU satellite is more complex than for the Hadley-Centre dataset, the only estimate that incorporates sea-surface temperature (SST) observations. Near f = 0.25 cyc/year, 4-year oscillation period, the CO2-coherence is particularly strong for the Hadley-Centre gridpoint temperature-anomaly time series from low-latitude oceans. This suggests that sea-surface temperature is a primary driver of the correlation, at least for the 0.2 < f < 0.5 cyc/yr bandpass where the El-Nino/Southern-Oscillation (ENSO) climate process dominates. Outside, the ENSO bandpass coherence is significant between 14 long-running GLOBALVIEW CO2-observing sites and the sea-level-pressure-based Southern Oscillation Index (SOI) and North Atlantic Oscillation (NAO) time series, consistent with wind stress and mixed-layer-thickness influences on ocean-atmosphere CO2 flux, independent of temperature fluctuations. Evidence for terrestrial biosphere influence is strongest in the leading principal component of GLOBALVIEW CO2-variability at f = 0.25 cpy, where a larger amplitude and a 4-month phase shift distinguish the mid- and high-latitude Northern Hemisphere CO2 fluctuations from those of the tropics and the Southern Hemisphere. The terrestrial signal we infer, however, coheres more strongly with oceanic-gridpoint temperatures than to continental-gridpoint temperatures. |
BibTeX:
@article{park11a,
author = {Park, Jeffrey},
title = {EVIDENCE FOR OCEANIC CONTROL OF INTERANNUAL CARBON CYCLE FEEDBACKS},
journal = {AMERICAN JOURNAL OF SCIENCE},
year = {2011},
volume = {311},
number = {6},
pages = {485--516},
doi = {10.2475/06.2011.01}
}
|
| Park C, Gerbig C, Newman S, Ahmadov R, Feng S, Gurney KR, Carmichael GR, Park S-Y, Lee H-W, Goulden M, Stutz J, Peischl J and Ryerson T ({2018}), "CO2 Transport, Variability, and Budget over the Southern California Air Basin Using the High-Resolution WRF-VPRM Model during the CalNex 2010 Campaign", JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY., JUN, {2018}. Vol. {57}({6}), pp. {1337-1352}. |
| Abstract: To study regional-scale carbon dioxide (CO2) transport, temporal variability, and budget over the Southern California Air Basin (SoCAB) during the California Research at the Nexus of Air Quality and Climate Change (CalNex) 2010 campaign period, a model that couples the Weather Research and Forecasting (WRF) Model with the Vegetation Photosynthesis and Respiration Model (VPRM) has been used. Our numerical simulations use anthropogenic CO2 emissions of the Hestia Project 2010 fossil-fuel CO2 emissions data products along with optimized VPRM parameters at ``FLUXNET'' sites, for biospheric CO2 fluxes over SoCAB. The simulated meteorological conditions have been validated with ground and aircraft observations, as well as with background CO2 concentrations from the coastal Palos Verdes site. The model captures the temporal pattern of CO2 concentrations at the ground site at the California Institute of Technology in Pasadena, but it overestimates the magnitude in early daytime. Analysis of CO2 by wind directions reveals the overestimate is due to advection from the south and southwest, where downtown Los Angeles is located. The model also captures the vertical profile of CO2 concentrations along with the flight tracks. The optimized VPRM parameters have significantly improved simulated net ecosystem exchange at each vegetation-class site and thus the regional CO2 budget. The total biospheric contribution ranges approximately from -24% to -20br> (daytime) of the total anthropogenic CO2 emissions during the study period. |
BibTeX:
@article{park18a,
author = {Park, Changhyoun and Gerbig, Christoph and Newman, Sally and Ahmadov, Ravan and Feng, Sha and Gurney, Kevin R. and Carmichael, Gregory R. and Park, Soon-Young and Lee, Hwa-Woon and Goulden, Mike and Stutz, Jochen and Peischl, Jeff and Ryerson, Tom},
title = {CO2 Transport, Variability, and Budget over the Southern California Air Basin Using the High-Resolution WRF-VPRM Model during the CalNex 2010 Campaign},
journal = {JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY},
year = {2018},
volume = {57},
number = {6},
pages = {1337-1352},
doi = {{10.1175/JAMC-D-17-0358.1}}
}
|
| Parker R, Boesch H, Cogan A, Fraser A, Feng L, Palmer PI, Messerschmidt J, Deutscher N, Griffith DWT, Notholt J, Wennberg PO and Wunch D ({2011}), "Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations", GEOPHYSICAL RESEARCH LETTERS., AUG 6, {2011}. Vol. {38} |
| Abstract: We report new short-wave infrared (SWIR) column retrievals of atmospheric methane (X(CH4)) from the Japanese Greenhouse Gases Observing SATellite (GOSAT) and compare observed spatial and temporal variations with correlative ground-based measurements from the Total Carbon Column Observing Network (TCCON) and with the global 3-D GEOS-Chem chemistry transport model. GOSAT X(CH4) retrievals are compared with daily TCCON observations at six sites between April 2009 and July 2010 (Bialystok, Park Falls, Lamont, Orleans, Darwin and Wollongong). GOSAT reproduces the site-dependent seasonal cycles as observed by TCCON with correlations typically between 0.5 and 0.7 with an estimated single-sounding precision between 0.4-0.8%. We find a latitudinal-dependent difference between the X(CH4) retrievals from GOSAT and TCCON which ranges from 17.9 ppb at the most northerly site (Bialystok) to -14.6 ppb at the site with the lowest latitude (Darwin). We estimate that the mean smoothing error difference included in the GOSAT to TCCON comparisons can account for 15.7 to 17.4 ppb for the northerly sites and for 1.1 ppb at the lowest latitude site. The GOSAT X(CH4) retrievals agree well with the GEOS-Chem model on annual (August 2009 - July 2010) and monthly timescales, capturing over 80% of the zonal variability. Differences between model and observed X(CH4) are found over key source regions such as Southeast Asia and central Africa which will be further investigated using a formal inverse model analysis. Citation: Parker, R., et al. (2011), Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations, Geophys. Res. Lett., 38, L15807, doi:10.1029/2011GL047871. |
BibTeX:
@article{parker11a,
author = {Parker, Robert and Boesch, Hartmut and Cogan, Austin and Fraser, Annemarie and Feng, Liang and Palmer, Paul I. and Messerschmidt, Janina and Deutscher, Nicholas and Griffith, David W. T. and Notholt, Justus and Wennberg, Paul O. and Wunch, Debra},
title = {Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations},
journal = {GEOPHYSICAL RESEARCH LETTERS},
year = {2011},
volume = {38},
doi = {10.1029/2011GL047871}
}
|
| Parker RJ, Boesch H, Byckling K, Webb AJ, Palmer PI, Feng L, Bergamaschi P, Chevallier F, Notholt J, Deutscher N, Warneke T, Hase F, Sussmann R, Kawakami S, Kivi R, Griffith DWT and Velazco V ({2015}), "Assessing 5 years of GOSAT Proxy XCH4 data and associated uncertainties", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({11}), pp. 4785-4801. |
| Abstract: We present 5 years of GOSAT XCH4 retrieved using the ``proxy'' approach. The Proxy XCH4 data are validated against ground-based TCCON observations and are found to be of high quality with a small bias of 4.8 ppb (similar to 0.27 and a single-sounding precision of 13.4 ppb (similar to 0.74 . The station-to-station bias (a measure of the relative accuracy) is found to be 4.2 ppb. For the first time the XCH4 = XCO2 ratio component of the Proxy retrieval is validated (bias of 0.014 ppbppm 1 (similar to 0.30 , single-sounding precision of 0.033 ppbppm 1 (similar to 0.72 ). The uncertainty relating to the model XCO2 component of the Proxy XCH4 is assessed through the use of an ensemble of XCO2 models. While each individual XCO2 model is found to agree well with the TCCON validation data (r = 0.94-0.97), it is not possible to select one model as the best from our comparisons. The median XCO2 value of the ensemble has a smaller scatter against TCCON (a standard deviation of 0.92 ppm) than any of the individual models whilst maintaining a small bias (0.15 ppm). This model median XCO2 is used to calculate the Proxy XCH4 with the maximum deviation of the ensemble from the median used as an estimate of the uncertainty. We compare this uncertainty to the a posteriori retrieval error (which is assumed to reduce with sqrt(N)) and find typically that the model XCO2 uncertainty becomes significant during summer months when the a posteriori error is at its lowest due to the increase in signal related to increased summertime reflected sunlight. We assess the significance of these model and retrieval uncertainties on flux inversion by comparing the GOSAT XCH4 against modelled XCH4 from TM5-4DVAR constrained by NOAA surface observations (MACC reanalysis scenario S1-NOAA). We find that for the majority of regions the differences are much larger than the estimated uncertainties. Our findings show that useful information will be provided to the inversions for the majority of regions in addition to that already provided by the assimilated surface measurements. |
BibTeX:
@article{parker15a,
author = {Parker, R. J. and Boesch, H. and Byckling, K. and Webb, A. J. and Palmer, P. I. and Feng, L. and Bergamaschi, P. and Chevallier, F. and Notholt, J. and Deutscher, N. and Warneke, T. and Hase, F. and Sussmann, R. and Kawakami, S. and Kivi, R. and Griffith, D. W. T. and Velazco, V.},
title = {Assessing 5 years of GOSAT Proxy XCH4 data and associated uncertainties},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2015},
volume = {8},
number = {11},
pages = {4785--4801},
doi = {10.5194/amt-8-4785-2015}
}
|
| Patra PK, Crisp D, Kaiser JW, Wunch D, Saeki T, Ichii K, Sekiya T, Wennberg PO, Feist DG, Pollard DF, Griffith DWT, Velazco VA, De Maziere M, Sha MK, Roehl C, Chatterjee A and Ishijima K ({2017}), "The Orbiting Carbon Observatory (OCO-2) tracks 2-3 peta-gram increase in carbon release to the atmosphere during the 2014-2016 El Nino", SCIENTIFIC REPORTS., OCT 19, {2017}. Vol. {7} |
| Abstract: The powerful El Nino event of 2015-2016 - the third most intense since the 1950s - has exerted a large impact on the Earth's natural climate system. The column-averaged CO2 dry-air mole fraction (XCO2) observations from satellites and ground-based networks are analyzed together with in situ observations for the period of September 2014 to October 2016. From the differences between satellite (OCO-2) observations and simulations using an atmospheric chemistry-transport model, we estimate that, relative to the mean annual fluxes for 2014, the most recent El Nino has contributed to an excess CO2 emission from the Earth's surface (land + ocean) to the atmosphere in the range of 2.4 +/- 0.2 PgC (1 Pg = 10(15) g) over the period of July 2015 to June 2016. The excess CO2 flux is resulted primarily from reduction in vegetation uptake due to drought, and to a lesser degree from increased biomass burning. It is about the half of the CO2 flux anomaly (range: 4.4-6.7 PgC) estimated for the 1997/1998 El Nino. The annual total sink is estimated to be 3.9 +/- 0.2 PgC for the assumed fossil fuel emission of 10.1 PgC. The major uncertainty in attribution arise from error in anthropogenic emission trends, satellite data and atmospheric transport. |
BibTeX:
@article{patra17a,
author = {Patra, Prabir K. and Crisp, David and Kaiser, Johannes W. and Wunch, Debra and Saeki, Tazu and Ichii, Kazuhito and Sekiya, Takashi and Wennberg, Paul O. and Feist, Dietrich G. and Pollard, David F. and Griffith, David W. T. and Velazco, Voltaire A. and De Maziere, M. and Sha, Mahesh K. and Roehl, Coleen and Chatterjee, Abhishek and Ishijima, Kentaro},
title = {The Orbiting Carbon Observatory (OCO-2) tracks 2-3 peta-gram increase in carbon release to the atmosphere during the 2014-2016 El Nino},
journal = {SCIENTIFIC REPORTS},
year = {2017},
volume = {7},
doi = {10.1038/s41598-017-13459-0}
}
|
| Paustian K, Lehmann J, Ogle S, Reay D, Robertson GP and Smith P ({2016}), "Climate-smart soils", NATURE., APR 7, {2016}. Vol. {532}({7597}), pp. 49-57. |
| Abstract: Soils are integral to the function of all terrestrial ecosystems and to food and fibre production. An overlooked aspect of soils is their potential to mitigate greenhouse gas emissions. Although proven practices exist, the implementation of soil-based greenhouse gas mitigation activities are at an early stage and accurately quantifying emissions and reductions remains a substantial challenge. Emerging research and information technology developments provide the potential for a broader inclusion of soils in greenhouse gas policies. Here we highlight `state of the art' soil greenhouse gas research, summarize mitigation practices and potentials, identify gaps in data and understanding and suggest ways to close such gaps through new research, technology and collaboration. |
BibTeX:
@article{paustian16a,
author = {Paustian, Keith and Lehmann, Johannes and Ogle, Stephen and Reay, David and Robertson, G. Philip and Smith, Pete},
title = {Climate-smart soils},
journal = {NATURE},
year = {2016},
volume = {532},
number = {7597},
pages = {49--57},
doi = {10.1038/nature17174}
}
|
| Peng C, Guiot J, Wu H, Jiang H and Luo Y ({2011}), "Integrating models with data in ecology and palaeoecology: advances towards a model-data fusion approach", ECOLOGY LETTERS., MAY, {2011}. Vol. {14}({5}), pp. 522-536. |
| Abstract: P>It is increasingly being recognized that global ecological research requires novel methods and strategies in which to combine process-based ecological models and data in cohesive, systematic ways. Model-data fusion (MDF) is an emerging area of research in ecology and palaeoecology. It provides a new quantitative approach that offers a high level of empirical constraint over model predictions based on observations using inverse modelling and data assimilation (DA) techniques. Increasing demands to integrate model and data methods in the past decade has led to MDF utilization in palaeoecology, ecology and earth system sciences. This paper reviews key features and principles of MDF and highlights different approaches with regards to DA. After providing a critical evaluation of the numerous benefits of MDF and its current applications in palaeoecology (i.e. palaeoclimatic reconstruction, palaeovegetation and palaeocarbon storage) and ecology (i.e. parameter and uncertainty estimation, model error identification, remote sensing and ecological forecasting), the paper discusses method limitations, current challenges and future research direction. In the ongoing data-rich era of today's world, MDF could become an important diagnostic and prognostic tool in which to improve our understanding of ecological processes while testing ecological theory and hypotheses and forecasting changes in ecosystem structure, function and services. |
BibTeX:
@article{peng11a,
author = {Peng, Changhui and Guiot, Joel and Wu, Haibin and Jiang, Hong and Luo, Yiqi},
title = {Integrating models with data in ecology and palaeoecology: advances towards a model-data fusion approach},
journal = {ECOLOGY LETTERS},
year = {2011},
volume = {14},
number = {5},
pages = {522--536},
doi = {10.1111/j.1461-0248.2011.01603.x}
}
|
| Peng Z, Zhang M, Kou X, Tian X and Ma X ({2015}), "A regional carbon data assimilation system and its preliminary evaluation in East Asia", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({2}), pp. 1087-1104. |
| Abstract: In order to optimize surface CO2 fluxes at grid scales, a regional surface CO2 flux inversion system (Carbon Flux Inversion system and Community Multi-scale Air Quality, CFI-CMAQ) has been developed by applying the ensemble Kalman filter (EnKF) to constrain the CO2 concentrations and applying the ensemble Kalman smoother (EnKS) to optimize the surface CO2 fluxes. The smoothing operator is associated with the atmospheric transport model to constitute a persistence dynamical model to forecast the surface CO2 flux scaling factors. In this implementation, the ``signal-to-noise'' problem can be avoided; plus, any useful observed information achieved by the current assimilation cycle can be transferred into the next assimilation cycle. Thus, the surface CO2 fluxes can be optimized as a whole at the grid scale in CFI-CMAQ. The performance of CFI-CMAQ was quantitatively evaluated through a set of Observing System Simulation Experiments (OSSEs) by assimilating CO2 retrievals from GOSAT (Greenhouse Gases Observing Satellite). The results showed that the CO2 concentration assimilation using EnKF could constrain the CO2 concentration effectively, illustrating that the simultaneous assimilation of CO2 concentrations can provide convincing CO2 initial analysis fields for CO2 flux inversion. In addition, the CO2 flux optimization using EnKS demonstrated that CFI-CMAQ could, in general, reproduce true fluxes at grid scales with acceptable bias. Two further sets of numerical experiments were conducted to investigate the sensitivities of the inflation factor of scaling factors and the smoother window. The results showed that the ability of CFI-CMAQ to optimize CO2 fluxes greatly relied on the choice of the inflation factor. However, the smoother window had a slight influence on the optimized results. CFI-CMAQ performed very well even with a short lag-window (e.g. 3 days). |
BibTeX:
@article{peng15a,
author = {Peng, Z. and Zhang, M. and Kou, X. and Tian, X. and Ma, X.},
title = {A regional carbon data assimilation system and its preliminary evaluation in East Asia},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2015},
volume = {15},
number = {2},
pages = {1087--1104},
doi = {10.5194/acp-15-1087-2015}
}
|
| Peng Z, Liu Z, Chen D and Ban J ({2017}), "Improving PM2.5 forecast over China by the joint adjustment of initial conditions and source emissions with an ensemble Kalman filter", ATMOSPHERIC CHEMISTRY AND PHYSICS., APR 13, {2017}. Vol. {17}({7}), pp. 4837-4855. |
| Abstract: In an attempt to improve the forecasting of atmospheric aerosols, the ensemble square root filter algorithm was extended to simultaneously optimize the chemical initial conditions (ICs) and emission input. The forecast model, which was expanded by combining the Weather Research and Forecasting with Chemistry (WRF-Chem) model and a forecast model of emission scaling factors, generated both chemical concentration fields and emission scaling factors. The forecast model of emission scaling factors was developed by using the ensemble concentration ratios of the WRF-Chem forecast chemical concentrations and also the time smoothing operator. Hourly surface fine particulate matter (PM2.5) observations were assimilated in this system over China from 5 to 16 October 2014. A series of 48 h forecasts was then carried out with the optimized initial conditions and emissions on each day at 00:00UTC and a control experiment was performed without data assimilation. In addition, we also performed an experiment of pure assimilation chemical ICs and the corresponding 48 h forecasts experiment for comparison. The results showed that the forecasts with the optimized initial conditions and emissions typically outperformed those from the control experiment. In the Yangtze River delta (YRD) and the Pearl River delta (PRD) regions, large reduction of the root-mean-square errors (RMSEs) was obtained for almost the entire 48 h forecast range attributed to assimilation. In particular, the relative reduction in RMSE due to assimilation was about 37.5% at nighttime when WRF-Chem performed comparatively worse. In the Beijing-Tianjin-Hebei (JJJ) region, relatively smaller improvements were achieved in the first 24 h forecast but then no improvements were achieved afterwards. Comparing to the forecasts with only the optimized ICs, the forecasts with the joint adjustment were always much better during the night in the PRD and YRD regions. However, they were very similar during daytime in both regions. Also, they performed similarly for almost the entire 48 h forecast range in the JJJ region. |
BibTeX:
@article{peng17a,
author = {Peng, Zhen and Liu, Zhiquan and Chen, Dan and Ban, Junmei},
title = {Improving PM2.5 forecast over China by the joint adjustment of initial conditions and source emissions with an ensemble Kalman filter},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2017},
volume = {17},
number = {7},
pages = {4837--4855},
doi = {10.5194/acp-17-4837-2017}
}
|
| Pérez IA, Sánchez ML, Garc\ia MÁ, Pardo N and Fernández-Duque B (2018), "The influence of meteorological variables on CO2 and CH4 trends recorded at a semi-natural station", Journal of environmental management. Vol. 209, pp. 37-45.
[BibTeX] |
BibTeX:
@article{perez18a,
author = {Pérez, Isidro A and Sánchez, M Luisa and Garc\ia, M Ángeles and Pardo, Nuria and Fernández-Duque, Beatriz},
title = {The influence of meteorological variables on CO2 and CH4 trends recorded at a semi-natural station},
journal = {Journal of environmental management},
year = {2018},
volume = {209},
pages = {37--45}
}
|
| Peters W, Jacobson AR, Sweeney C, Andrews AE, Conway TJ, Masarie K, Miller JB, Bruhwiler LMP, Petron G, Hirsch AI, Worthy DEJ, van der Werf GR, Randerson JT, Wennberg PO, Krol MC and Tans PP ({2007}), "An atmospheric perspective on North American carbon dioxide exchange: CarbonTracker", PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA., NOV 27, {2007}. Vol. {104}({48}), pp. 18925-18930. |
BibTeX:
@article{peters07a,
author = {Peters, Wouter and Jacobson, Andrew R. and Sweeney, Colm and Andrews, Arlyn E. and Conway, Thomas J. and Masarie, Kenneth and Miller, John B. and Bruhwiler, Lori M. P. and Petron, Gabrielle and Hirsch, Adam I. and Worthy, Douglas E. J. and van der Werf, Guido R. and Randerson, James T. and Wennberg, Paul O. and Krol, Maarten C. and Tans, Pieter P.},
title = {An atmospheric perspective on North American carbon dioxide exchange: CarbonTracker},
journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
year = {2007},
volume = {104},
number = {48},
pages = {18925--18930},
doi = {10.1073/pnas.0708986104}
}
|
| Peters W, Krol MC, van der Werf GR, Houweling S, Jones CD, Hughes J, Schaefer K, Masarie KA, Jacobson AR, Miller JB, Cho CH, Ramonet M, Schmidt M, Ciattaglia L, Apadula F, Helta D, Meinhardt F, di Sarra AG, Piacentino S, Sferlazzo D, Aalto T, Hatakka J, Strom J, Haszpra L, Meijer HAJ, van der Laan S, Neubert REM, Jordan A, Rodo X, Morgui JA, Vermeulen AT, Popa E, Rozanski K, Zimnoch M, Manning AC, Leuenberger M, Uglietti C, Dolman AJ, Ciais P, Heimann M and Tans PP ({2010}), "Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations", GLOBAL CHANGE BIOLOGY., APR, {2010}. Vol. {16}({4}), pp. 1317-1337. |
| Abstract: We present an estimate of net ecosystem exchange (NEE) of CO2 in Europe for the years 2001-2007. It is derived with a data assimilation that uses a large set of atmospheric CO2 mole fraction observations (similar to 70 000) to guide relatively simple descriptions of terrestrial and oceanic net exchange, while fossil fuel and fire emissions are prescribed. Weekly terrestrial sources and sinks are optimized (i.e., a flux inversion) for a set of 18 large ecosystems across Europe in which prescribed climate, weather, and surface characteristics introduce finer scale gradients. We find that the terrestrial biosphere in Europe absorbed a net average of -165 Tg C yr-1 over the period considered. This uptake is predominantly in non-EU countries, and is found in the northern coniferous (-94 Tg C yr-1) and mixed forests (-30 Tg C yr-1) as well as the forest/field complexes of eastern Europe (-85 Tg C yr-1). An optimistic uncertainty estimate derived using three biosphere models suggests the uptake to be in a range of -122 to -258 Tg C yr-1, while a more conservative estimate derived from the a-posteriori covariance estimates is -165 +/- 437 Tg C yr-1. Note, however, that uncertainties are hard to estimate given the nature of the system and are likely to be significantly larger than this. Interannual variability in NEE includes a reduction in uptake due to the 2003 drought followed by 3 years of more than average uptake. The largest anomaly of NEE occurred in 2005 concurrent with increased seasonal cycles of observed CO2. We speculate these changes to result from the strong negative phase of the North Atlantic Oscillation in 2005 that lead to favorable summer growth conditions, and altered horizontal and vertical mixing in the atmosphere. All our results are available through http://www.carbontracker.eu. |
BibTeX:
@article{peters10a,
author = {Peters, W. and Krol, M. C. and van der Werf, G. R. and Houweling, S. and Jones, C. D. and Hughes, J. and Schaefer, K. and Masarie, K. A. and Jacobson, A. R. and Miller, J. B. and Cho, C. H. and Ramonet, M. and Schmidt, M. and Ciattaglia, L. and Apadula, F. and Helta, D. and Meinhardt, F. and di Sarra, A. G. and Piacentino, S. and Sferlazzo, D. and Aalto, T. and Hatakka, J. and Strom, J. and Haszpra, L. and Meijer, H. A. J. and van der Laan, S. and Neubert, R. E. M. and Jordan, A. and Rodo, X. and Morgui, J. -A. and Vermeulen, A. T. and Popa, E. and Rozanski, K. and Zimnoch, M. and Manning, A. C. and Leuenberger, M. and Uglietti, C. and Dolman, A. J. and Ciais, P. and Heimann, M. and Tans, P. P.},
title = {Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations},
journal = {GLOBAL CHANGE BIOLOGY},
year = {2010},
volume = {16},
number = {4},
pages = {1317--1337},
doi = {10.1111/j.1365-2486.2009.02078.x}
}
|
| Peters CN, Bennartz R and Hornberger GM ({2017}), "Satellite-derived methane emissions from inundation in Bangladesh", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., MAY, {2017}. Vol. {122}({5}), pp. 1137-1155. |
| Abstract: The uncertainty in methane (CH4) source strength of rice fields and wetlands is particularly high in South Asia CH4 budgets. We used satellite observations of CH4 column mixing ratios from Atmospheric Infrared Sounder (AIRS), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), and Greenhouse Gases Observing Satellite (GOSAT) to estimate the contribution of Bangladesh emissions to atmospheric CH4 concentrations. Using satellite-derived inundation area as a proxy for source area, we developed a simple inverse advection model that estimates average annual CH4 surface fluxes to be 4, 9, and 19mgCH(4)m(-2)h(-1) in AIRS, SCIAMACHY, and GOSAT, respectively. Despite this variability, our flux estimates varied over a significantly narrower range than reported values for CH4 surface fluxes from a survey of 32 studies reporting ground-based observations between 0 and 260mgCH(4)m(-2)h(-1). Upscaling our satellite-derived surface flux estimates, we estimated total annual CH4 emissions for Bangladesh to be 1.33.2, 1.82.0, 3.11.6Tgyr(-1), depending on the satellite. Our estimates of total emissions are in line with the median of total emission values for Bangladesh reported in earlier studies. Plain Language Summary The extent of methane emissions from flooded areas, such as wetlands and rice paddies, is not well understood, particularly in South Asia. This study uses satellite observations of atmospheric methane and flooding to explore seasonal fluctuation in methane emissions from Bangladesh. Our findings suggest methane emissions similar to previously thought. |
BibTeX:
@article{peters17a,
author = {Peters, C. N. and Bennartz, R. and Hornberger, G. M.},
title = {Satellite-derived methane emissions from inundation in Bangladesh},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
year = {2017},
volume = {122},
number = {5},
pages = {1137--1155},
doi = {10.1002/2016JG003740}
}
|
| Peters W, van der Velde IR, van Schaik E, Miller JB, Ciais P, Duarte HF, van der Laan-Luijkx IT, van der Molen MK, Scholze M, Schaefer K, Vidale PL, Verhoef A, Wårlind D, Zhu D, Tans PP, Vaughn B and White JWC (2018), "Increased water-use efficiency and reduced CO 2 uptake by plants during droughts at a continental scale", NATURE GEOSCIENCE. Vol. 11, pp. 744-748. |
BibTeX:
@article{peters18a,
author = {Peters, Wouter and van der Velde, Ivar R. and van Schaik, Erik and Miller, John B. and Ciais, Philippe and Duarte, Henrique F. and van der Laan-Luijkx, Ingrid T. and van der Molen, Michiel K. and Scholze, Marko and Schaefer, Kevin and Vidale, Pier Luigi and Verhoef, Anne and Wårlind, David and Zhu, Dan and Tans, Pieter P. and Vaughn, Bruce and White, James W. C.},
title = {Increased water-use efficiency and reduced CO 2 uptake by plants during droughts at a continental scale},
journal = {NATURE GEOSCIENCE},
year = {2018},
volume = {11},
pages = {744-748},
url = {https://www.nature.com/articles/s41561-018-0212-7}
}
|
| Peylin P, Law RM, Gurney KR, Chevallier F, Jacobson AR, Maki T, Niwa Y, Patra PK, Peters W, Rayner PJ, Roedenbeck C, van der Laan-Luijkx IT and Zhang X ({2013}), "Global atmospheric carbon budget: results from an ensemble of atmospheric CO2 inversions", BIOGEOSCIENCES. Vol. {10}({10}), pp. 6699-6720. |
| Abstract: Atmospheric CO2 inversions estimate surface carbon fluxes from an optimal fit to atmospheric CO2 measurements, usually including prior constraints on the flux estimates. Eleven sets of carbon flux estimates are compared, generated by different inversions systems that vary in their inversions methods, choice of atmospheric data, transport model and prior information. The inversions were run for at least 5 yr in the period between 1990 and 2010. Mean fluxes for 2001-2004, seasonal cycles, interannual variability and trends are compared for the tropics and northern and southern extra-tropics, and separately for land and ocean. Some continental/basin-scale subdivisions are also considered where the atmospheric network is denser. Four-year mean fluxes are reasonably consistent across inversions at global/latitudinal scale, with a large total (land plus ocean) carbon uptake in the north (-3.4 Pg C yr(-1) (+/- 0.5 Pg C yr(-1) standard deviation), with slightly more uptake over land than over ocean), a significant although more variable source over the tropics (1.6 +/- 0.9 Pg C yr(-1)) and a compensatory sink of similar magnitude in the south (-1.4 +/- 0.5 Pg C yr(-1)) corresponding mainly to an ocean sink. Largest differences across inversions occur in the balance between tropical land sources and southern land sinks. Interannual variability (IAV) in carbon fluxes is larger for land than ocean regions (standard deviation around 1.06 versus 0.33 Pg C yr(-1) for the 1996-2007 period), with much higher consistency among the inversions for the land. While the tropical land explains most of the IAV (standard deviation similar to 0.65 Pg C yr(-1)), the northern and southern land also contribute (standard deviation similar to 0.39 Pg C yr(-1)). Most inversions tend to indicate an increase of the northern land carbon uptake from late 1990s to 2008 (around 0.1 Pg C yr(-1)), predominantly in North Asia. The mean seasonal cycle appears to be well constrained by the atmospheric data over the northern land (at the continental scale), but still highly dependent on the prior flux seasonality over the ocean. Finally we provide recommendations to interpret the regional fluxes, along with the uncertainty estimates. |
BibTeX:
@article{peylin13a,
author = {Peylin, P. and Law, R. M. and Gurney, K. R. and Chevallier, F. and Jacobson, A. R. and Maki, T. and Niwa, Y. and Patra, P. K. and Peters, W. and Rayner, P. J. and Roedenbeck, C. and van der Laan-Luijkx, I. T. and Zhang, X.},
title = {Global atmospheric carbon budget: results from an ensemble of atmospheric CO2 inversions},
journal = {BIOGEOSCIENCES},
year = {2013},
volume = {10},
number = {10},
pages = {6699--6720},
doi = {10.5194/bg-10-6699-2013}
}
|
| Piao SL, Ito A, Li SG, Huang Y, Ciais P, Wang XH, Peng SS, Nan HJ, Zhao C, Ahlstrom A, Andres RJ, Chevallier F, Fang JY, Hartmann J, Huntingford C, Jeong S, Levis S, Levy PE, Li JS, Lomas MR, Mao JF, Mayorga E, Mohammat A, Muraoka H, Peng CH, Peylin P, Poulter B, Shen ZH, Shi X, Sitch S, Tao S, Tian HQ, Wu XP, Xu M, Yu GR, Viovy N, Zaehle S, Zeng N and Zhu B ({2012}), "The carbon budget of terrestrial ecosystems in East Asia over the last two decades", BIOGEOSCIENCES. Vol. {9}({9}), pp. 3571-3586. |
| Abstract: This REgional Carbon Cycle Assessment and Processes regional study provides a synthesis of the carbon balance of terrestrial ecosystems in East Asia, a region comprised of China, Japan, North and South Korea, and Mongolia. We estimate the current terrestrial carbon balance of East Asia and its driving mechanisms during 1990-2009 using three different approaches: inventories combined with satellite greenness measurements, terrestrial ecosystem carbon cycle models and atmospheric inversion models. The magnitudes of East Asia's terrestrial carbon sink from these three approaches are comparable: -0.293 +/- 0.033 PgC yr(-1) from inventory-remote sensing model-data fusion approach, -0.413 +/- 0.141 PgC yr(-1)(not considering biofuel emissions) or -0.224 +/- 0.141 PgC yr(-1) (considering biofuel emissions) for carbon cycle models, and -0.270 +/- 0.507 PgC yr(-1) for atmospheric inverse models. Here and in the following, the numbers behind +/- signs are standard deviations. The ensemble of ecosystem modeling based analyses further suggests that at the regional scale, climate change and rising atmospheric CO2 together resulted in a carbon sink of -0.289 +/- 0.135 PgC yr(-1), while land-use change and nitrogen deposition had a contribution of -0.013 +/- 0.029 PgC yr(-1) and -0.107 +/- 0.025 PgC yr(-1), respectively. Although the magnitude of climate change effects on the carbon balance varies among different models, all models agree that in response to climate change alone, southern China experienced an increase in carbon storage from 1990 to 2009, while northern East Asia including Mongolia and north China showed a decrease in carbon storage. Overall, our results suggest that about 13-27% of East Asia's CO2 emissions from fossil fuel burning have been offset by carbon accumulation in its terrestrial territory over the period from 1990 to 2009. The underlying mechanisms of carbon sink over East Asia still remain largely uncertain, given the diversity and intensity of land management processes, and the regional conjunction of many drivers such as nutrient deposition, climate, atmospheric pollution and CO2 changes, which cannot be considered as independent for their effects on carbon storage. |
BibTeX:
@article{piao12a,
author = {Piao, S. L. and Ito, A. and Li, S. G. and Huang, Y. and Ciais, P. and Wang, X. H. and Peng, S. S. and Nan, H. J. and Zhao, C. and Ahlstrom, A. and Andres, R. J. and Chevallier, F. and Fang, J. Y. and Hartmann, J. and Huntingford, C. and Jeong, S. and Levis, S. and Levy, P. E. and Li, J. S. and Lomas, M. R. and Mao, J. F. and Mayorga, E. and Mohammat, A. and Muraoka, H. and Peng, C. H. and Peylin, P. and Poulter, B. and Shen, Z. H. and Shi, X. and Sitch, S. and Tao, S. and Tian, H. Q. and Wu, X. P. and Xu, M. and Yu, G. R. and Viovy, N. and Zaehle, S. and Zeng, N. and Zhu, B.},
title = {The carbon budget of terrestrial ecosystems in East Asia over the last two decades},
journal = {BIOGEOSCIENCES},
year = {2012},
volume = {9},
number = {9},
pages = {3571--3586},
doi = {10.5194/bg-9-3571-2012}
}
|
| Pickett-Heaps CA, Rayner PJ, Law RM, Ciais P, Patra PK, Bousquet P, Peylin P, Maksyutov S, Marshall J, Roedenbeck C, Langenfelds RL, Steele LP, Francey RJ, Tans P and Sweeney C ({2011}), "Atmospheric CO2 inversion validation using vertical profile measurements: Analysis of four independent inversion models", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUN 25, {2011}. Vol. {116} |
| Abstract: We present the results of a validation of atmospheric inversions of CO2 fluxes using four transport models. Each inversion uses data primarily from surface stations, combined with an atmospheric transport model, to estimate surface fluxes. The validation (or model evaluation) consists of running these optimized fluxes through the forward model and comparing the simulated concentrations with airborne concentration measurements. We focus on profiles from Cape Grim, Tasmania, and Carr, Colorado, while using other profile sites to test the generality of the comparison. Fits to the profiles are generally worse than to the surface data from the inversions and worse than the expected model-data mismatch. Thus inversion estimates are generally not consistent with the profile measurements. The TM3 model does better by some measures than the other three models. Models perform better over Tasmania than Colorado, and other profile sites bear out a general improvement from north to south and from continental to marine locations. There are also errors in the interannual variability of the fit, consistent in time and common across models. This suggests real variations in sources visible to the profile but not the surface measurements. |
BibTeX:
@article{pickett-heaps11a,
author = {Pickett-Heaps, C. A. and Rayner, P. J. and Law, R. M. and Ciais, P. and Patra, P. K. and Bousquet, P. and Peylin, P. and Maksyutov, S. and Marshall, J. and Roedenbeck, C. and Langenfelds, R. L. and Steele, L. P. and Francey, R. J. and Tans, P. and Sweeney, C.},
title = {Atmospheric CO2 inversion validation using vertical profile measurements: Analysis of four independent inversion models},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2010JD014887}
}
|
| Pillai D, Gerbig C, Marshall J, Ahmadov R, Kretschmer R, Koch T and Karstens U ({2010}), "High resolution modeling of CO2 over Europe: implications for representation errors of satellite retrievals", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({1}), pp. 83-94. |
| Abstract: Satellite retrievals for column CO2 with better spatial and temporal sampling are expected to improve the current surface flux estimates of CO2 via inverse techniques. However, the spatial scale mismatch between remotely sensed CO2 and current generation inverse models can induce representation errors, which can cause systematic biases in flux estimates. This study is focused on estimating these representation errors associated with utilization of satellite measurements in global models with a horizontal resolution of about 1 degree or less. For this we used simulated CO2 from the high resolution modeling framework WRF-VPRM, which links CO2 fluxes from a diagnostic biosphere model to a weather forecasting model at 10x10 km(2) horizontal resolution. Sub-grid variability of column averaged CO2, i.e. the variability not resolved by global models, reached up to 1.2 ppm with a median value of 0.4 ppm. Statistical analysis of the simulation results indicate that orography plays an important role. Using sub-grid variability of orography and CO2 fluxes as well as resolved mixing ratio of CO2, a linear model can be formulated that could explain about 50% of the spatial patterns in the systematic (bias or correlated error) component of representation error in column and near-surface CO2 during day- and night-times. These findings give hints for a parameterization of representation error which would allow for the representation error to taken into account in inverse models or data assimilation systems. |
BibTeX:
@article{pillai10a,
author = {Pillai, D. and Gerbig, C. and Marshall, J. and Ahmadov, R. and Kretschmer, R. and Koch, T. and Karstens, U.},
title = {High resolution modeling of CO2 over Europe: implications for representation errors of satellite retrievals},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2010},
volume = {10},
number = {1},
pages = {83--94},
doi = {10.5194/acp-10-83-2010}
}
|
| Pilon L, Berberoglu H and Kandilian R ({2011}), "Radiation transfer in photobiological carbon dioxide fixation and fuel production by microalgae", JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER., NOV, {2011}. Vol. {112}({17}), pp. 2639-2660. |
| Abstract: Solar radiation is the energy source driving the metabolic activity of microorganisms able to photobiologically fixate carbon dioxide and convert solar energy into biofuels. Thus, careful radiation transfer analysis must be conducted in order to design and operate efficient photobioreactors. This review paper first introduces light harvesting mechanisms used by microorganisms as well as photosynthesis and photobiological fuel production. It then provides a thorough and critical review of both experimental and modeling efforts focusing on radiation transfer in microalgae suspension. Experimental methods to determine the radiation characteristics of microalgae are presented. Methods for solving the radiation transfer equation in photobioreactors with or without bubbles are also discussed. Sample measurements and numerical solutions are provided. Finally, novel strategies for achieving optimum light delivery and maximizing sunlight utilization in photobioreactors are discussed including genetic engineering of microorganisms with truncated chlorophyll antenna. (C) 2011 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{pilon11a,
author = {Pilon, Laurent and Berberoglu, Halil and Kandilian, Razmig},
title = {Radiation transfer in photobiological carbon dioxide fixation and fuel production by microalgae},
journal = {JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER},
year = {2011},
volume = {112},
number = {17},
pages = {2639--2660},
doi = {10.1016/j.jqsrt.2011.07.004}
}
|
| Pino D, Kaikkonen JP and de Arellano JV-G ({2013}), "Quantifying the uncertainties of advection and boundary layer dynamics on the diurnal carbon dioxide budget", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., AUG 27, {2013}. Vol. {118}({16}), pp. 9376-9392. |
| Abstract: We investigate the uncertainties in the carbon dioxide (CO2) mixing ratio and inferred surface flux associated with boundary layer processes and advection by using mixed-layer theory. By extending the previous analysis presented by Pino et al. (2012), new analytical expressions are derived to quantify the uncertainty of CO2 mixing ratio or surface flux associated to, among others, boundary layer depth, early morning CO2 mixing ratio at the mixed layer or at the free atmosphere; or CO2 advection. We identify and calculate two sorts of uncertainties associated to the CO2 mixing ratio and surface flux: instantaneous and past (due to advection). The numerical experiments are guided and constrained by meteorological and CO2 observations taken at the Cabauw 213 m tower. We select 2 days (25 September 2003 and 12 March 2004) with a well-defined convective boundary layer but different CO2 advection contributions. Our sensitivity analysis shows that uncertainty of the CO2 advection in the boundary layer due to instantaneous uncertainties represents at 1600 LT on 12 March 2004 a contribution of 2ppm and 0.072 mg m(-2)s(-1) in the uncertainty of the CO2 mixing ratio and inferred surface flux, respectively. Taking into account that the monthly averaged minimum CO2 surface flux for March 2004 was -0.55 mg m(-2)s(-1), the error on the surface flux is on the order of 10%. By including CO2 advection in the analytical expressions, we demonstrate that the uncertainty of the CO2 mixing ratio or surface flux also depends on the past uncertainties of the boundary layer depth. |
BibTeX:
@article{pino13a,
author = {Pino, D. and Kaikkonen, J. -P. and de Arellano, J. Vila-Guerau},
title = {Quantifying the uncertainties of advection and boundary layer dynamics on the diurnal carbon dioxide budget},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2013},
volume = {118},
number = {16},
pages = {9376--9392},
doi = {10.1002/jgrd.50677}
}
|
| Polavarapu SM, Neish M, Tanguay M, Girard C, de Grandpre J, Semeniuk K, Gravel S, Ren S, Roche S, Chan D and Strong K ({2016}), "Greenhouse gas simulations with a coupled meteorological and transport model: the predictability of CO2", ATMOSPHERIC CHEMISTRY AND PHYSICS., SEP 26, {2016}. Vol. {16}({18}), pp. 12005-12038. |
| Abstract: A new model for greenhouse gas transport has been developed based on Environment and Climate Change Canada's operational weather and environmental prediction models. When provided with realistic posterior fluxes for CO2, the CO2 simulations compare well to NOAA's Carbon-Tracker fields and to near-surface continuous measurements, columns from the Total Carbon Column Observing Network (TCCON) and NOAA aircraft profiles. This coupled meteorological and tracer transport model is used to study the predictability of CO2. Predictability concerns the quantification of model forecast errors and thus of transport model errors. CO2 predictions are used to compute model-data mismatches when solving flux inversion problems and the quality of such predictions is a major concern. Here, the loss of meteorological predictability due to uncertain meteorological initial conditions is shown to impact CO2 predictability. The predictability of CO2 is shorter than that of the temperature field and increases near the surface and in the lower stratosphere. When broken down into spatial scales, CO2 predictability at the very largest scales is mainly due to surface fluxes but there is also some sensitivity to the land and ocean surface forcing of meteorological fields. The predictability due to the land and ocean surface is most evident in boreal summer when biospheric uptake produces large spatial gradients in the CO2 field. This is a newly identified source of uncertainty in CO2 predictions but it is expected to be much less significant than uncertainties in fluxes. However, it serves as an upper limit for the more important source of transport error and loss of predictability, which is due to uncertain meteorological analyses. By isolating this component of transport error, it is demonstrated that CO2 can only be defined on large spatial scales due to the presence of meteorological uncertainty. Thus, for a given model, there is a spatial scale below which fluxes cannot be inferred simply due to the fact that meteorological analyses are imperfect. These unresolved spatial scales correspond to small scales near the surface but increase with altitude. By isolating other components of transport error, the largest or limiting error can be identified. For example, a model error due to the lack of convective tracer transport was found to impact transport error on the very largest (wavenumbers less than 5) spatial scales. Thus for wavenumbers greater than 5, transport model error due to meteorological analysis uncertainty is more important for our model than the lack of convective tracer transport. |
BibTeX:
@article{polavarapu16a,
author = {Polavarapu, Saroja M. and Neish, Michael and Tanguay, Monique and Girard, Claude and de Grandpre, Jean and Semeniuk, Kirill and Gravel, Sylvie and Ren, Shuzhan and Roche, Sebastien and Chan, Douglas and Strong, Kimberly},
title = {Greenhouse gas simulations with a coupled meteorological and transport model: the predictability of CO2},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2016},
volume = {16},
number = {18},
pages = {12005--12038},
doi = {10.5194/acp-16-12005-2016}
}
|
| Polavarapu SM, Deng F, Byrne B, Jones DBA and Neish M ({2018}), "A comparison of posterior atmospheric CO2 adjustments obtained from in situ and GOSAT constrained flux inversions", ATMOSPHERIC CHEMISTRY AND PHYSICS., AUG 22, {2018}. Vol. {18}({16}), pp. {12011-12044}. |
| Abstract: Posterior fluxes obtained from inverse modelling are difficult to verify because there is no dense network of flux measurements available to evaluate estimates against. Here we present a new diagnostic to evaluate structures in posterior fluxes. First, we simulate the change in atmospheric CO2 fields between posterior and prior fluxes, referred to as the posterior atmospheric adjustments due to updated fluxes (PAAFs). Second, we calculate the uncertainty in atmospheric CO2 fields due solely to uncertainty in the meteorological fields, referred to as the posterior atmospheric adjustments due to imperfect meteorology (PAAMs). We argue that PAAF can only be considered robust if it exceeds PAAM, that is, the changes in atmospheric CO2 between the posterior and prior fluxes should at least exceed atmospheric CO2 changes arising from imperfect meteorology. This diagnostic is applied to two CO2 flux inversions: one which assimilates observations from the in situ CO2 network and the other which assimilates observations from the Greenhouse Gases Observing SATellite (GOSAT). On the global scale, PAAF in the troposphere reflects northern extratropical fluxes, whereas stratospheric adjustments primarily reflect tropical fluxes. In general, larger spatiotemporal variations in PAAF are obtained for the GOSAT inversion than for the in situ inversion. Zonal standard deviations of the PAAF exceed the PAAM through most of the year when GOSAT observations are used, but the minimum value is exceeded only in boreal summer when in situ observations are used. Zonal spatial structures in GOSAT-based PAAF exceed PAAM throughout the year in the tropics and through most of the year in the northern extratropics, suggesting GOSAT flux inversions can constrain zonal asymmetries in fluxes. However, we cannot discount the possibility that these structures are influenced by biases in GOSAT retrievals. Verification of such spatial structures will require a dense network of independent observations. Because PAAF depends on the choice of prior fluxes, the comparison with PAAM is system dependent and thus can be used to monitor a given assimilation system's behaviour. |
BibTeX:
@article{polavarapu18a,
author = {Polavarapu, Saroja M. and Deng, Feng and Byrne, Brendan and Jones, Dylan B. A. and Neish, Michael},
title = {A comparison of posterior atmospheric CO2 adjustments obtained from in situ and GOSAT constrained flux inversions},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2018},
volume = {18},
number = {16},
pages = {12011-12044}
}
|
| Pradhan R, Goroshi S and Singh RP ({2014}), "SPATIAL AND SEASONAL CHARACTERIZATION OF TERRESTRIAL BIOSPHERIC CARBON FLUX OVER INDIA USING GOSAT DATA", In ISPRS TECHNICAL COMMISSION VIII SYMPOSIUM. Vol. {40-8}, pp. 617-621. |
| Abstract: Carbon plays a crucial role in determining the ecosystem balance and slight changes in its concentration in the atmosphere can have significant impacts. The launch of JAXA's GOSAT (Greenhouse gases Observing SATellite) in 2009 has started a new era of high accuracy CO2 concentration and flux measurements from space borne sensors. This paper reports the spatial and temporal variability of terrestrial biospheric carbon fluxes over the agro-climatic zones of India derived using GOSAT data for the period June 2009 to October 2011. The country averaged biospheric carbon flux varied from -0.47 (October) to 0.37 (April) gC m(-2) day(-1). Maximum variability in fluxes was observed for the North-Eastern region (-2.18 to + 1.38 gC m(-2) day(-1)) whereas the dry region of Rajasthan showed extremely low values (-0.1 to + 0.1 gC m(-2) day(-1)). The temporal variation in flux values was compared to averaged NDVI for each zone and indicated that growing season corresponds to more sequestration of carbon from the atmosphere. We compared GOSAT derived biospheric flux with Carbon Tracker (CT) data and observed that the two values show good agreement for all months except June and July. This study provides new estimates of biospheric carbon flux using satellite data driven models to better understand the carbon dynamics associated with terrestrial biosphere over India. |
BibTeX:
@inproceedings{pradhan14a,
author = {Pradhan, Rohit and Goroshi, Sheshakumar and Singh, Raghavendra P.},
editor = {Dadhwal, VK and Diwakar, PG and Seshasai, MVR and Raju, PLN and Hakeem, A},
title = {SPATIAL AND SEASONAL CHARACTERIZATION OF TERRESTRIAL BIOSPHERIC CARBON FLUX OVER INDIA USING GOSAT DATA},
booktitle = {ISPRS TECHNICAL COMMISSION VIII SYMPOSIUM},
year = {2014},
volume = {40-8},
pages = {617--621},
note = {ISPRS Technical Commission VIII Symposium, Hyderabad, INDIA, DEC 09-12, 2014},
doi = {10.5194/isprsarchives-XL-8-617-2014}
}
|
| Pu J, Xu H, Kang L and Ma Q (2011), "Characteristics of Atmopsheric CO2 Concentration and Variation of Carbon Source & Sink at Lin'an Regional Background Station", Environmental Science. Vol. 32(8)
[BibTeX] |
BibTeX:
@article{pu11a,
author = {Pu, Jingjiao and Xu, Honghui and Kang, Lili and Ma, Qianli},
title = {Characteristics of Atmopsheric CO2 Concentration and Variation of Carbon Source & Sink at Lin'an Regional Background Station},
journal = {Environmental Science},
year = {2011},
volume = {32},
number = {8}
}
|
| Le Quéré C, Canadell JG, Ciais P, Dhakal S, Patwardhan A, Raupach MR and Young OR (2010), "An International Carbon Office to assist policy-based science", Current Opinion in Environmental Sustainability. Vol. 2(4), pp. 297-300.
[BibTeX] |
BibTeX:
@article{quere10a,
author = {Le Quéré, Corinne and Canadell, Josep G and Ciais, Philippe and Dhakal, Shobhakar and Patwardhan, Anand and Raupach, Michael R and Young, Oran R},
title = {An International Carbon Office to assist policy-based science},
journal = {Current Opinion in Environmental Sustainability},
year = {2010},
volume = {2},
number = {4},
pages = {297--300}
}
|
| Raczka BM, Davis KJ, Huntzinger D, Neilson RP, Poulter B, Richardson AD, Xiao J, Baker I, Ciais P, Keenan TF, Law B, Post WM, Ricciuto D, Schaefer K, Tian H, Tomelleri E, Verbeeck H and Viovy N ({2013}), "Evaluation of continental carbon cycle simulations with North American flux tower observations", ECOLOGICAL MONOGRAPHS., NOV, {2013}. Vol. {83}({4}), pp. 531-556. |
| Abstract: Terrestrial biosphere models can help identify physical processes that control carbon dynamics, including land-atmosphere CO2 fluxes, and have great potential to predict the terrestrial ecosystem response to changing climate. The skill of models that provide continental-scale carbon flux estimates, however, remains largely untested. This paper evaluates the performance of continental-scale flux estimates from 17 models against observations from 36 North American flux towers. Fluxes extracted from regional model simulations were compared with co-located flux tower observations at monthly and annual time increments. Site-level model simulations were used to help interpret sources of the mismatch between the regional simulations and site-based observations. On average, the regional model runs overestimated the annual gross primary productivity (5 and total respiration (15, and they significantly underestimated the annual net carbon uptake (64 during the time period 2000-2005. Comparison with site-level simulations implicated choices specific to regional model simulations as contributors to the gross flux biases, but not the net carbon uptake bias. The models performed the best at simulating carbon exchange at deciduous broadleaf sites, likely because a number of models used prescribed phenology to simulate seasonal fluxes. The models did not perform as well for crop, grass, and evergreen sites. The regional models matched the observations most closely in terms of seasonal correlation and seasonal magnitude of variation, but they have very little skill at interannual correlation and minimal skill at interannual magnitude of variability. The comparison of site vs. regional-level model runs demonstrated that (1) the interannual correlation is higher for site-level model runs, but the skill remains low; and (2) the underestimation of year-to-year variability for all fluxes is an inherent weakness of the models. The best-performing regional models that did not use flux tower calibration were CLM-CN, CASA-GFEDv2, and SIB3.1. Two flux tower calibrated, empirical models, EC-MOD and MOD17 broken vertical bar, performed as well as the best process-based models. This suggests that (1) empirical, calibrated models can perform as well as complex, process-based models and (2) combining process-based model structure with relevant constraining data could significantly improve model performance. |
BibTeX:
@article{raczka13a,
author = {Raczka, Brett M. and Davis, Kenneth J. and Huntzinger, Deborah and Neilson, Ronald P. and Poulter, Benjamin and Richardson, Andrew D. and Xiao, Jingfeng and Baker, Ian and Ciais, Philippe and Keenan, Trevor F. and Law, Beverly and Post, Wilfred M. and Ricciuto, Daniel and Schaefer, Kevin and Tian, Hanqin and Tomelleri, Enrico and Verbeeck, Hans and Viovy, Nicolas},
title = {Evaluation of continental carbon cycle simulations with North American flux tower observations},
journal = {ECOLOGICAL MONOGRAPHS},
year = {2013},
volume = {83},
number = {4},
pages = {531--556},
doi = {10.1890/12-0893.1}
}
|
| Rajan N, Maas SJ and Cui S ({2013}), "Extreme Drought Effects on Carbon Dynamics of a Semiarid Pasture", AGRONOMY JOURNAL., NOV-DEC, {2013}. Vol. {105}({6}), pp. 1749-1760. |
| Abstract: Environmental and management factors are critical in determining the C source or sink status of agroecosystems. Information on the C dynamics of an ecosystem from source to sink and vice versa are critical in determining the role of that ecosystem in regional and global C balances. We investigated the impact of the 2011 mega-drought on seasonal changes in net CO2 exchange of a WW-B. Dahl Old World bluestem [Bothriochloa bladhii (Retz) S.T. Blake] pasture in the Texas High Plains and compared the results with those from 2010, a hydrologically wet year. Carbon dioxide flux between the vegetation and atmosphere was measured using an eddy covariance flux tower. Our results indicate that net ecosystem exchange, ecosystem respiration, and gross primary production for this agroecosystem were strongly affected by environmental variables and grazing. During the period of measurement in 2010 (Days of the Year 152-365), the pasture accumulated 164 g C m(-2) and was a net C sink. During the same period in 2011, the severe drought changed the dynamics of the pasture from a C sink to a source, with a net cumulative loss of 142 g C m(-2). Ecosystem respiration was an exponential function of soil temperature in both years. When extreme water-limiting days were excluded, the exponential model explained 90br> of the variation in ecosystem respiration in 2011 and 92% of the variation in ecosystem respiration in 2010. Incorporating the results from our study with ecosystem models can improve our understanding of the contributions of managed pastures to regional C balances. |
BibTeX:
@article{rajan13a,
author = {Rajan, Nithya and Maas, Stephan J. and Cui, Song},
title = {Extreme Drought Effects on Carbon Dynamics of a Semiarid Pasture},
journal = {AGRONOMY JOURNAL},
year = {2013},
volume = {105},
number = {6},
pages = {1749--1760},
doi = {10.2134/agronj2013.0112}
}
|
| Reed ZD, Sperling B, van Zee RD, Whetstone JR, Gillis KA and Hodges JT ({2014}), "Photoacoustic spectrometer for accurate, continuous measurements of atmospheric carbon dioxide concentration", APPLIED PHYSICS B-LASERS AND OPTICS., NOV, {2014}. Vol. {117}({2}), pp. 645-657. |
| Abstract: We have developed a portable photoacoustic spectrometer that offers routine, precise and accurate measurements of the molar concentration of atmospheric carbon. The temperature-controlled spectrometer continuously samples dried atmospheric air and employs an intensity-modulated distributed feedback laser and fiber amplifier operating near 1.57 A mu m. For measurements of carbon dioxide in air, we demonstrate a measurement precision (60-s averaging time) of 0.15 A mu mol mol(-1) and achieve a standard uncertainty of 0.8 A mu mol mol(-1) by calibrating the analyzer response in terms of certified gas mixtures. We also investigate how water vapor affects the photoacoustic signal by promoting collisional relaxation of the carbon dioxide. |
BibTeX:
@article{reed14a,
author = {Reed, Zachary D. and Sperling, Brent and van Zee, Roger D. and Whetstone, James R. and Gillis, Keith A. and Hodges, Joseph T.},
title = {Photoacoustic spectrometer for accurate, continuous measurements of atmospheric carbon dioxide concentration},
journal = {APPLIED PHYSICS B-LASERS AND OPTICS},
year = {2014},
volume = {117},
number = {2},
pages = {645--657},
doi = {10.1007/s00340-014-5878-y}
}
|
| Rella CW, Chen H, Andrews AE, Filges A, Gerbig C, Hatakka J, Karion A, Miles NL, Richardson SJ, Steinbacher M, Sweeney C, Wastine B and Zellweger C ({2013}), "High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {6}({3}), pp. 837-860. |
| Abstract: Traditional techniques for measuring the mole fractions of greenhouse gases in the well-mixed atmosphere have required dry sample gas streams (dew point < -25 degrees C) to achieve the inter-laboratory compatibility goals set forth by the Global Atmosphere Watch programme of the World Meteorological Organisation (WMO/GAW) for carbon dioxide (+/- 0.1 ppm in the Northern Hemisphere and +/- 0.05 ppm in the Southern Hemisphere) and methane (+/- 2 ppb). Drying the sample gas to low levels of water vapour can be expensive, time-consuming, and/or problematic, especially at remote sites where access is difficult. Recent advances in optical measurement techniques, in particular cavity ring down spectroscopy, have led to the development of greenhouse gas analysers capable of simultaneous measurements of carbon dioxide, methane and water vapour. Unlike many older technologies, which can suffer from significant uncorrected interference from water vapour, these instruments permit accurate and precise greenhouse gas measurements that can meet the WMO/GAW inter-laboratory compatibility goals (WMO, 2011a) without drying the sample gas. In this paper, we present laboratory methodology for empirically deriving the water vapour correction factors, and we summarise a series of in-situ validation experiments comparing the measurements in humid gas streams to well-characterised dry-gas measurements. By using the manufacturer-supplied correction factors, the dry-mole fraction measurements have been demonstrated to be well within the GAW compatibility goals up to a water vapour concentration of at least 1%. By determining the correction factors for individual instruments once at the start of life, this water vapour concentration range can be extended to at least 2% over the life of the instrument, and if the correction factors are determined periodically over time, the evidence suggests that this range can be extended up to and even above 4% water vapour concentrations. |
BibTeX:
@article{rella13a,
author = {Rella, C. W. and Chen, H. and Andrews, A. E. and Filges, A. and Gerbig, C. and Hatakka, J. and Karion, A. and Miles, N. L. and Richardson, S. J. and Steinbacher, M. and Sweeney, C. and Wastine, B. and Zellweger, C.},
title = {High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2013},
volume = {6},
number = {3},
pages = {837--860},
doi = {10.5194/amt-6-837-2013}
}
|
| Reuter M, Buchwitz M, Schneising O, Heymann J, Bovensmann H and Burrows JP ({2010}), "A method for improved SCIAMACHY CO2 retrieval in the presence of optically thin clouds", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {3}({1}), pp. 209-232. |
| Abstract: An optimal estimation based retrieval scheme for satellite based retrievals of XCO2 ( the dry air column averaged mixing ratio of atmospheric CO2) is presented enabling accurate retrievals also in the presence of thin clouds. The proposed method is designed to analyze near-infrared nadir measurements of the SCIAMACHY instrument in the CO2 absorption band at 1580 nm and in the O-2-A absorption band at around 760nm. The algorithm accounts for scattering in an optically thin cirrus cloud layer and at aerosols of a default profile. The scattering information is mainly obtained from the O-2-A band and a merged fit windows approach enables the transfer of information between the O-2-A and the CO2 band. Via the optimal estimation technique, the algorithm is able to account for a priori information to further constrain the inversion. Test scenarios of simulated SCIAMACHY sun-normalized radiance measurements are analyzed in order to specify the quality of the proposed method. In contrast to existing algorithms for SCIAMACHY retrievals, the systematic errors due to cirrus clouds with optical thicknesses up to 1.0 are reduced to values below 4ppm for most of the analyzed scenarios. This shows that the proposed method has the potential to reduce uncertainties of SCIAMACHY retrieved XCO2 making this data product potentially useful for surface flux inverse modeling. |
BibTeX:
@article{reuter10a,
author = {Reuter, M. and Buchwitz, M. and Schneising, O. and Heymann, J. and Bovensmann, H. and Burrows, J. P.},
title = {A method for improved SCIAMACHY CO2 retrieval in the presence of optically thin clouds},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2010},
volume = {3},
number = {1},
pages = {209--232},
doi = {10.5194/amt-3-209-2010}
}
|
| Reuter M, Bovensmann H, Buchwitz M, Burrows JP, Connor BJ, Deutscher NM, Griffith DWT, Heymann J, Keppel-Aleks G, Messerschmidt J, Notholt J, Petri C, Robinson J, Schneising O, Sherlock V, Velazco V, Warneke T, Wennberg PO and Wunch D ({2011}), "Retrieval of atmospheric CO2 with enhanced accuracy and precision from SCIAMACHY: Validation with FTS measurements and comparison with model results", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., FEB 23, {2011}. Vol. {116} |
| Abstract: The Bremen Optimal Estimation differential optical absorption spectroscopy (DOAS) (BESD) algorithm for satellite based retrievals of XCO2 (the column-average dry-air mole fraction of atmospheric CO2) has been applied to Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) data. It uses measurements in the O-2-A absorption band to correct for scattering of undetected clouds and aerosols. Comparisons with precise and accurate ground-based Fourier transform spectrometer (FTS) measurements at four Total Carbon Column Observing Network (TCCON) sites have been used to quantify the quality of the new SCIAMACHY XCO2 data set. Additionally, the results have been compared to NOAA's assimilation system CarbonTracker. The comparisons show that the new retrieval meets the expectations from earlier theoretical studies. We find no statistically significant regional XCO2 biases between SCIAMACHY and the FTS instruments. However, the standard error of the systematic differences is in the range of 0.2 ppm and 0.8 ppm. The XCO2 single-measurement precision of 2.5 ppm is similar to theoretical estimates driven by instrumental noise. There are no significant differences found for the year-to-year increase as well as for the average seasonal amplitude between SCIAMACHY XCO2 and the collocated FTS measurements. Comparison of the year-to-year increase and also of the seasonal amplitude of CarbonTracker exhibit significant differences with the corresponding FTS values at Darwin. Here the differences between SCIAMACHY and CarbonTracker are larger than the standard error of the SCIAMACHY values. The difference of the seasonal amplitude exceeds the significance level of 2 standard errors. Therefore, our results suggest that SCIAMACHY may provide valuable additional information about XCO2, at least in regions with a low density of in situ measurements. |
BibTeX:
@article{reuter11a,
author = {Reuter, M. and Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Connor, B. J. and Deutscher, N. M. and Griffith, D. W. T. and Heymann, J. and Keppel-Aleks, G. and Messerschmidt, J. and Notholt, J. and Petri, C. and Robinson, J. and Schneising, O. and Sherlock, V. and Velazco, V. and Warneke, T. and Wennberg, P. O. and Wunch, D.},
title = {Retrieval of atmospheric CO2 with enhanced accuracy and precision from SCIAMACHY: Validation with FTS measurements and comparison with model results},
journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
year = {2011},
volume = {116},
doi = {10.1029/2010JD015047}
}
|
| Reuter M, Buchwitz M, Schneising O, Hase F, Heymann J, Guerlet S, Cogan AJ, Bovensmann H and Burrows JP ({2012}), "A simple empirical model estimating atmospheric CO2 background concentrations", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({6}), pp. 1349-1357. |
| Abstract: A simple empirical CO2 model (SECM) is presented to estimate column-average dry-air mole fractions of atmospheric CO2 (XCO2) as well as mixing ratio profiles. SECM is based on a simple equation depending on 17 empirical parameters, latitude, and date. The empirical parameters have been determined by least squares fitting to NOAA's (National Oceanic and Atmospheric Administration) assimilation system CarbonTracker version 2010 (CT2010). Comparisons with TCCON (total carbon column observing network) FTS (Fourier transform spectrometer) measurements show that SECM XCO2 agrees quite well with reality. The synthetic XCO2 values have a standard error of 1.39 ppm and systematic station-to-station biases of 0.46 ppm. Typical column averaging kernels of the TCCON FTS, a SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY), and two GOSAT (Greenhouse gases Observing SATellite) XCO2 retrieval algorithms have been used to assess the smoothing error introduced by using SECM profiles instead of CT2010 profiles as a priori. The additional smoothing error amounts to 0.17 ppm for a typical SCIAMACHY averaging kernel and is most times much smaller for the other instruments (e.g. 0.05 ppm for a typical TCCON FTS averaging kernel). Therefore, SECM is well suited to provide a priori information for state-of-the-art ground-based (FTS) and satellite-based (GOSAT, SCIAMACHY) XCO2 retrievals. Other potential applications are: (i) near real-time processing systems (that cannot make use of models like CT2010 operated in delayed mode), (ii) `CO2 proxy' methods for XCH4 retrievals (as correction for the XCO2 background), and (iii) observing system simulation experiments especially for future satellite missions. |
BibTeX:
@article{reuter12a,
author = {Reuter, M. and Buchwitz, M. and Schneising, O. and Hase, F. and Heymann, J. and Guerlet, S. and Cogan, A. J. and Bovensmann, H. and Burrows, J. P.},
title = {A simple empirical model estimating atmospheric CO2 background concentrations},
journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
year = {2012},
volume = {5},
number = {6},
pages = {1349--1357},
doi = {10.5194/amt-5-1349-2012}
}
|
| Reuter M, Bovensmann H, Buchwitz M, Burrows JP, Deutscher NM, Heymann J, Rozanov A, Schneising O, Suto H, Toon GC and Warneke T ({2012}), "On the potential of the 2041-2047 nm spectral region for remote sensing of atmospheric CO2 isotopologues", JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER., NOV, {2012}. Vol. {113}({16}), pp. 2009-2017. |
| Abstract: Pressing open questions about the carbon cycle can be addressed with precise measurements of the three most abundant CO2 isotopologues (OCO)-O-16-C-12-O-16, (OCO)-O-16-C-13-O-16, and (OCO)-O-16-C-12-O-18. Such measurements can, e.g., help to further constrain oceanic and biospheric net fluxes or to differentiate between the gross biospheric fluxes photosynthesis and respiration. The 2041-2047 nm (about 4885-4900 cm(-1)) spectral region contains separated absorption lines of the three most abundant CO2 isotopologues. Their spectral properties make this spectral region well suited for the use of a light path proxy method for the retrieval of delta C-13 and delta O-18 (the ratio of heavier to lighter isotopologues relative to a standard). An optimal estimation based light path proxy retrieval for delta C-13 and delta O-18 has been set up, applicable to GOSAT (Greenhouse gases Observing Satellite) and ground-based FTS (Fourier transform spectrometer) measurements. Initial results show that it is possible to retrieve delta C-13 and delta O-18 from ground-based FTS instruments with a precision of 0.6-1.6 parts per thousand and from GOSAT with a precision of about 30 parts per thousand. Comparison of the achievable precision with the expected atmospheric signals shows that ground-based FTS remote sensing measurements have the potential to gain valuable information on delta C-13 and delta O-18 if averaging a sufficient number of measurements. It seems unlikely that this applies also to GOSAT because of the lower precision and a conceptual larger sensitivity to scattering related errors in satellite viewing geometry. (C) 2012 Elsevier Ltd. All rights reserved. |
BibTeX:
@article{reuter12b,
author = {Reuter, M. and Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Deutscher, N. M. and Heymann, J. and Rozanov, A. and Schneising, O. and Suto, H. and Toon, G. C. and Warneke, T.},
title = {On the potential of the 2041-2047 nm spectral region for remote sensing of atmospheric CO2 isotopologues},
journal = {JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER},
year = {2012},
volume = {113},
number = {16},
pages = {2009--2017},
doi = {10.1016/j.jqsrt.2012.07.013}
}
|
| Reuter M, Boesch H, Bovensmann H, Bril A, Buchwitz M, Butz A, Burrows JP, O'Dell CW, Guerlet S, Hasekamp O, Heymann J, Kikuchi N, Oshchepkov S, Parker R, Pfeifer S, Schneising O, Yokota T and Yoshida Y ({2013}), "A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions: the ensemble median algorithm EMMA", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({4}), pp. 1771-1780. |
| Abstract: We analyze an ensemble of seven XCO2 retrieval algorithms for SCIAMACHY (scanning imaging absorption spectrometer of atmospheric chartography) and GOSAT (greenhouse gases observing satellite). The ensemble spread can be interpreted as regional uncertainty and can help to identify locations for new TCCON (total carbon column observing network) validation sites. Additionally, we introduce the ensemble median algorithm EMMA combining individual soundings of the seven algorithms into one new data set. The ensemble takes advantage of the algorithms' independent developments. We find ensemble spreads being often < 1 ppm but rising up to 2 ppm especially in the tropics and East Asia. On the basis of gridded monthly averages, we compare EMMA and all individual algorithms with TCCON and CarbonTracker model results (potential outliers, north/south gradient, seasonal (peak-to-peak) amplitude, standard deviation of the difference). Our findings show that EMMA is a promising candidate for inverse modeling studies. Compared to CarbonTracker, the satellite retrievals find consistently larger north/south gradients (by 0.3-0.9 ppm) and seasonal amplitudes (by 1.5-2.0 ppm). |
BibTeX:
@article{reuter13a,
author = {Reuter, M. and Boesch, H. and Bovensmann, H. and Bril, A. and Buchwitz, M. and Butz, A. and Burrows, J. P. and O'Dell, C. W. and Guerlet, S. and Hasekamp, O. and Heymann, J. and Kikuchi, N. and Oshchepkov, S. and Parker, R. and Pfeifer, S. and Schneising, O. and Yokota, T. and Yoshida, Y.},
title = {A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions: the ensemble median algorithm EMMA},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2013},
volume = {13},
number = {4},
pages = {1771--1780},
doi = {10.5194/acp-13-1771-2013}
}
|
| Reuter M, Buchwitz M, Hilboll A, Richter A, Schneising O, Hilker M, Heymann J, Bovensmann H and Burrows JP ({2014}), "Decreasing emissions of NOx relative to CO2 in East Asia inferred from satellite observations", NATURE GEOSCIENCE., NOV, {2014}. Vol. {7}({11}), pp. 792-795. |
| Abstract: At present, global CO2 emission inventories are mainly based on bottom-up estimates that rely, for example, on reported fossil fuel consumptions and fuel types(1,2). The associated uncertainties propagate into the CO2-to-NOx emission ratios that are used in pollution prediction and monitoring(3), as well as into biospheric carbon fluxes derived by inverse models(4). Here we analyse simultaneous and co-located satellite retrievals from SCIAMACHY (ref. 5; SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY) of the column-average dry-air mole fraction of CO2 (refs 6,7) and NO2 (refs 8-10) for the years 2003-2011 to provide a top-down estimate of trends in emissions and in the ratio between CO2 and NOx emissions. Our analysis shows that the CO2-to-NOx emission ratio has increased by 4.2 +/- 1.7% yr(-1) in East Asia. In this region, we find a large positive trend of CO2 emissions (9.8 +/- 1.7% yr(-1)), which we largely attribute to the growing Chinese economy. This trend exceeds the positive trend of NOx emissions (5.8 +/- 0.9% yr(-1)). Our findings suggest that the recently installed and renewed technology in East Asia, such as power plants, transportation and so on, is cleaner in terms of NOx emissions than the old infrastructure, and roughly matches relative emission levels in North America and Europe. |
BibTeX:
@article{reuter14a,
author = {Reuter, M. and Buchwitz, M. and Hilboll, A. and Richter, A. and Schneising, O. and Hilker, M. and Heymann, J. and Bovensmann, H. and Burrows, J. P.},
title = {Decreasing emissions of NOx relative to CO2 in East Asia inferred from satellite observations},
journal = {NATURE GEOSCIENCE},
year = {2014},
volume = {7},
number = {11},
pages = {792--795},
doi = {10.1038/NGEO2257}
}
|
| Reuter M, Buchwitz M, Hilker M, Heymann J, Schneising O, Pillai D, Bovensmann H, Burrows JP, Boesch H, Parker R, Butz A, Hasekamp O, O'Dell CW, Yoshida Y, Gerbig C, Nehrkorn T, Deutscher NM, Warneke T, Notholt J, Hase F, Kivi R, Sussmann R, Machida T, Matsueda H and Sawa Y ({2014}), "Satellite-inferred European carbon sink larger than expected", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({24}), pp. 13739-13753. |
| Abstract: Current knowledge about the European terrestrial biospheric carbon sink, from the Atlantic to the Urals, relies upon bottom-up inventory and surface flux inverse model estimates (e.g. 0.27 +/- 0.16 GtCa(-1) for 2000-2005 (Schulze et al., 2009), 0.17 +/- 0.44 GtCa(-1) for 2001-2007 (Peters et al., 2010), 0.45 +/- 0.40 GtCa(-1) for 2010 (Chevallier et al., 2014), 0.40 +/- 0.42 GtCa(-1) for 2001-2004 (Peylin et al., 2013)). Inverse models assimilate in situ CO2 atmospheric concentrations measured by surface-based air sampling networks. The intrinsic sparseness of these networks is one reason for the relatively large flux uncertainties (Peters et al., 2010; Bruhwiler et al., 2011). Satellite-based CO2 measurements have the potential to reduce these uncertainties (Miller et al., 2007; Chevallier et al., 2007). Global inversion experiments using independent models and independent GOSAT satellite data products consistently derived a considerably larger European sink (1.0-1.3 GtCa(-1) for 09/2009-08/2010 (Basu et al., 2013), 1.2-1.8 GtCa(-1) in 2010 (Chevallier et al., 2014)). However, these results have been considered unrealistic due to potential retrieval biases and/or transport errors (Chevallier et al., 2014) or have not been discussed at all (Basu et al., 2013; Takagi et al., 2014). Our analysis comprises a regional inversion approach using STILT (Gerbig et al., 2003; Lin et al., 2003) short-range (days) particle dispersion modelling, rendering it insensitive to large-scale retrieval biases and less sensitive to long-range transport errors. We show that the satellite-derived European terrestrial carbon sink is indeed much larger (1.02 +/- 0.30 GtCa(-1) in 2010) than previously expected. This is qualitatively consistent among an ensemble of five different inversion set-ups and five independent satellite retrievals (BESD (Reuter et al., 2011) 2003-2010, ACOS (O'Dell et al., 2012) 2010, UoL-FP (Cogan et al., 2012) 2010, RemoTeC (Butz et al., 2011) 2010, and NIES (Yoshida et al., 2013) 2010) using data from two different instruments (SCIAMACHY (Bovensmann et al., 1999) and GOSAT (Kuze et al., 2009)). The difference to in situ based inversions (Peylin et al., 2013), whilst large with respect to the mean reported European carbon sink (0.4 GtCa(-1) for 2001-2004), is similar in magnitude to the reported uncertainty (0.42 GtCa(-1)). The highest gain in information is obtained during the growing season when satellite observation conditions are advantageous, a priori uncertainties are largest, and the surface sink maximises; during the dormant season, the results are dominated by the a priori. Our results provide evidence that the current understanding of the European carbon sink has to be revisited. |
BibTeX:
@article{reuter14b,
author = {Reuter, M. and Buchwitz, M. and Hilker, M. and Heymann, J. and Schneising, O. and Pillai, D. and Bovensmann, H. and Burrows, J. P. and Boesch, H. and Parker, R. and Butz, A. and Hasekamp, O. and O'Dell, C. W. and Yoshida, Y. and Gerbig, C. and Nehrkorn, T. and Deutscher, N. M. and Warneke, T. and Notholt, J. and Hase, F. and Kivi, R. and Sussmann, R. and Machida, T. and Matsueda, H. and Sawa, Y.},
title = {Satellite-inferred European carbon sink larger than expected},
journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
year = {2014},
volume = {14},
number = {24},
pages = {13739--13753},
doi = {10.5194/acp-14-13739-2014}
}
|
| Reuter M, Buchwitz M, Schneising O, Noel S, Rozanov V, Bovensmann H and Burrows JP ({2017}), "A Fast Atmospheric Trace Gas Retrieval for Hyperspectral Instruments Approximating Multiple ScatteringPart 1: Radiative Transfer and a Potential OCO-2 XCO2 Retrieval Setup", REMOTE SENSING., NOV, {2017}. Vol. {9}({11}) |
| Abstract: Satellite retrievals of the atmospheric dry-air column-average mole fraction of CO2 (XCO2) based on hyperspectral measurements in appropriate near (NIR) and short wave infrared (SWIR) O2 and CO2 absorption bands can help to answer important questions about the carbon cycle but the precision and accuracy requirements for XCO2 data products are demanding. Multiple scattering of light at aerosols and clouds can be a significant error source for XCO2 retrievals. Therefore, so called full physics retrieval algorithms were developed aiming to minimize scattering related errors by explicitly fitting scattering related properties such as cloud water/ ice content, aerosol optical thickness, cloud height, etc. However, the computational costs for multiple scattering radiative transfer (RT) calculations can be immense. Processing all data of the Orbiting Carbon Observatory-2 (OCO-2) can require up to thousands of CPU cores and the next generation of CO2 monitoring satellites will produce at least an order of magnitude more data. Here we introduce the Fast atmOspheric traCe gAs retrievaL FOCAL including a scalar RT model which approximates multiple scattering effects with an analytic solution of the RT problem of an isotropic scattering layer and a Lambertian surface. The computational performance is similar to an absor |