Climatology of Aerosol Radiative Properties in the Free Troposphere
E. Andrews1, J.A. Ogren2, P. Bonasoni3, A. Marinoni3, E. Cuevas4, S. Rodriguez4, J. Sun5, D. Jaffe6, E. Fischer6, U. Baltensperger7, E. Weingartner7, M.C. Coen8, S. Sharma9, A. Macdonald9, W.R. Leaitch9, G. Lin10, P. Laj11, J. Stamenov12, I. Kalapov12, A. Jefferson1 and P. Sheridan2
1Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309; 303-497-5171, E-mail: betsy.andrews@noaa.gov
2NOAA Earth System Research Laboratory, Boulder, CO 80305
3Institute of Atmospheric Sciences and Climate, National Research Council, Bologna I-40129, Italy
4Izaña Atmospheric Research Centre, Santa Cruz de Tenerife, Canary Islands
5Centre for Atmosphere Watch and Services, Chinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing 100081, China
6Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195
7Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, Villigen CH-5232, Switzerland
8Federal Office of Meteorology and Climatology, MeteoSwiss, Payerne CH-1530, Switzerland
9Environment Canada, Toronto, Ontario M3H 5T4, Canada
10Department of Atmospheric Sciences, National Central University, Chung-Li, Taiwan
11Laboratoire de Glaciologie et Géophysique de lEnvironement, University of Grenoble, Grenoble, France
12Institute for Nuclear Research and Nuclear Energy, Sofia BG-1784, Italy
High-altitude mountaintop observatories provide the opportunity to study aerosol properties in the free troposphere without the added expense and difficulty of making airborne measurements. Here we present statistics of means, variability, and trends of aerosol radiative properties, including light scattering, light absorption, light extinction, single scattering albedo, Ångström exponent, hemispheric backscatter fraction and radiative forcing efficiency, from various high altitude measurements. These climatologies utilize data from ten mountaintop observatories in the 20-50ºN latitude band: Mauna Loa, USA; Lulin Mountain, Taiwan; Pyramid, Nepal; Izaña, Spain; Mount Waliguan, China; Beo Moussala, Bulgaria; Mount Bachelor, USA; Monte Cimone, Italy; Jungfraujoch, Switzerland; Whistler Mountain, Canada. Results are also included from two multi-year, in-situ aerosol vertical profiling programs: Southern Great Plains, USA and Bondville, USA. Figure 1 shows the monthly climatology of free troposphere aerosol scattering at Mauna Loa Observatory, and demonstrates the well-documented effect of long range transport from Asia in the springtime months. By taking this data set as a whole and developing a self-consistent climatology, the combined observatory measurements of free tropospheric aerosol radiative properties have the potential to contribute to aerosol-climate research in a way that far exceeds the contribution from individual observatories. For example, this type of analysis may help constrain chemical transport models and validate satellite measurements.
Figure 1. Monthly climatology of aerosol scattering at Mauna Loa (1974-2009), USA.