First Deployment of a New Mobile Laboratory for Greenhouse Gas Attribution Studies
R. Bambha1, H. Michelsen1, P. Schrader1, F. Helsel2, M.D. Ivey2, B.D. Zak2, B. LaFranchi3, B. Flowers4, T. Rahn4, M. Dubey4, T. Guilderson3, S. Biraud5, M. Fischer5, M. Torn5 and C. Sweeney6
1Sandia National Laboratories, 7011 East Ave, Livermore, CA 94550; 925-294-3391, E-mail: rpbambh@sandia.gov
2Sandia National Laboratories, Albuquerque, NM 87185
3Lawrence Livermore National Laboratory, Livermore, CA 94550
4Los Alamos National Laboratory, Los Alamos, NM 87545
5Lawrence Berkeley National Laboratory, Berkeley, CA 94720
6Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309
Anthropogenic sources of carbon dioxide (CO2) represent a significant portion of the global carbon budget, but partitioning CO2 measurements into their biogenic and anthropogenic sources has been difficult using only measurements of CO2 abundances and those of a small number of additional tracers. An intensive field campaign was conducted in Fall 2010 at the Atmospheric Radiation Measurement-Southern Great Plains (ARM-SGP) Central facility near Lamont, OK to measure CO2 and several tracers for its sources using a new mobile laboratory. Two trucks carrying over fifteen instruments for gases and particles were deployed along with a gas-calibration system. Air was drawn into both trucks from a 10-m tall mast. All measurements were made either from a common inlet or closely located inlets. Instruments were selected to provide measurements of tracers of both biogenic and anthropogenic sources. High-frequency measurements of abundances of CO2 and its stable isotopologues (13CO2 and C18OO) were made simultaneously with measurements of CO, SO2, NOx, O3, CH4, water vapor isotopologues (H2O, HDO, and H218O), volatile organic compounds, black and organic carbon aerosol, and particle count. Automated flask samplers collected whole air samples for off-line 14C analysis using accelerator mass spectrometry. Redundancy between CO2, CH4, and H2O measurements provided a valuable crosscheck for the calibrations and the measurements. Good agreement between CO2 measurements from four different instruments was attained following careful post-processing and calibrations. Similarly good agreement was demonstrated between four instruments that measured water vapor and two instruments that measured CH4. The agricultural region that surrounds the ARM-SGP site had experienced little rainfall prior to the campaign, and land cover and crop growth were minimal during the period in which measurements were made (3 October - 9 November 2010). Correlations between various tracers and CO2 provide insight into the different sources, including the anthropogenic component, which includes biomass and fossil fuel combustion.
Figure 1. Time series of δ13C -CO2, Δ14C-CO2, δD-H2O, H2O, and CO measured during the campaign. High δ13C and Δ14C are associated with low CO, δD -H2O, and H2O and air from high altitudes. Low δ13C and Δ14C and high CO, δD-H2O, and H2O are associated with air from low altitudes within the past few days.