Atmos. Chem. Phys. Discuss., 9, 15769-15825, 2009
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Evaluation of black carbon estimations in global aerosol models
D. Koch1,2, M. Schulz3, S. Kinne4, T. C. Bond6, Y. Balkanski3, S. Bauer1,2, T. Berntsen13, O. Boucher14, M. Chin15, A. Clarke10, N. De Luca26, F. Dentener16, T. Diehl17, O. Dubovik14, R. Easter18, D. W. Fahey9, J. Feichter4, D. Fillmore23, S. Freitag10, S. Ghan18, P. Ginoux19, S. Gong20, L. Horowitz19, T. Iversen13,28, A. Kirkevåg28, Z. Klimont7, Y. Kondo11, M. Krol12, X. Liu18,25, C. McNaughton10, R. Miller2, V. Montanaro25, N. Moteki11, G. Myhre13,21, J. E. Penner24, Ja. Perlwitz1,2, G. Pitari25, S. Reddy14, L. Sahu11, H. Sakamoto11, G. Schuster5, J. P. Schwarz9, Ø. Seland28, J. R. Spackman9, P. Stier26, N. Takegawa11, T. Takemura27, C. Textor3, J. A. van Aardenne8, and Y. Zhao22
1Columbia University, New York, NY, USA
3Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France
4Max-Planck-Institut fur Meteorologie, Hamburg, Germany
5NASA Langley Research Center, Hampton, Virginia, USA
6University of Illinois at Urbana-Champaign, Urbana, IL, USA
7International Institute for Applied Systems Analysis, Laxenburg, Austria
8European Commission, Institute for Environment and Sustainability, Joint Research Centre, Ispra, Italy
9NOAA Earth System Research Laboratory, Chemical Sciences Division and Cooperative Inst. for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
10University of Hawaii at Manoa, Honolulu, Hawaii, USA
11RCAST, University of Tokyo, Japan
12Meteorology and Air Quality, Wageningen University, Wageningen, The Netherlands
13University of Oslo, Oslo, Norway
14Universite des Sciences et Technologies de Lille, CNRS, Villeneuve d'Ascq, France
15NASA Goddard Space Flight Center, Greenbelt, MD, USA
16EC, Joint Research Centre, Institute for Environment and Sustainability, Italy
17University of Maryland Baltimore County, Baltimore, Maryland, USA
18Battelle Pacific Northwest Division, Pacific Northwest National Laboratory, Richland, USA
19NOAA, Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA
20ARQM Meteorological Service Canada, Toronto, Canada
21Center for International Climate and Environmental Research – Oslo (CICERO) Oslo, Norway
22University of California – Davis, CA, USA
23NCAR, Boulder, CO, USA
24University of Michigan, Ann Arbor, MI, USA
25Universita degli Studi L'Aquila, Italy
26Atmospheric, Oceanic and Planetary Physics, University of Oxford, UK
27Kyushu University, Fukuoka, Japan
28Norwegian Meteorological Institute, Oslo, Norway

Abstract. We evaluate black carbon (BC) model predictions from the AeroCom model intercomparison project by considering the diversity among year 2000 model simulations and comparing model predictions with available measurements. These model-measurement intercomparisons include BC surface and aircraft concentrations, aerosol absorption optical depth (AAOD) from AERONET and Ozone Monitoring Instrument (OMI) retrievals and BC column estimations based on AERONET. In regions other than Asia, most models are biased high compared to surface concentration measurements. However compared with (column) AAOD or BC burden retreivals, the models are generally biased low. The average ratio of model to retrieved AAOD is less than 0.7 in South American and 0.6 in African biomass burning regions; both of these regions lack surface concentration measurements. In Asia the average model to observed ratio is 0.6 for AAOD and 0.5 for BC surface concentrations. Compared with aircraft measurements over the Americas at latitudes between 0 and 50 N, the average model is a factor of 10 larger than observed, and most models exceed the measured BC standard deviation in the mid to upper troposphere. At higher latitudes the average model to aircraft BC is 0.6 and underestimates the observed BC loading in the lower and middle troposphere associated with springtime Arctic haze. Low model bias for AAOD but overestimation of surface and upper atmospheric BC concentrations at lower latitudes suggests that most models are underestimating BC absorption and should improve estimates for refractive index, particle size, and optical effects of BC coating. Retrieval uncertainties and/or differences with model diagnostic treatment may also contribute to the model-measurement disparity. Largest AeroCom model diversity occurred in northern Eurasia and the remote Arctic, regions influenced by anthropogenic sources. Changing emissions, aging, removal, or optical properties within a single model generated a smaller change in model predictions than the range represented by the full set of AeroCom models. Upper tropospheric concentrations of BC mass from the aircraft measurements are suggested to provide a unique new benchmark to test scavenging and vertical dispersion of BC in global models.

Citation: Koch, D., Schulz, M., Kinne, S., Bond, T. C., Balkanski, Y., Bauer, S., Berntsen, T., Boucher, O., Chin, M., Clarke, A., De Luca, N., Dentener, F., Diehl, T., Dubovik, O., Easter, R., Fahey, D. W., Feichter, J., Fillmore, D., Freitag, S., Ghan, S., Ginoux, P., Gong, S., Horowitz, L., Iversen, T., Kirkevåg, A., Klimont, Z., Kondo, Y., Krol, M., Liu, X., McNaughton, C., Miller, R., Montanaro, V., Moteki, N., Myhre, G., Penner, J. E., Perlwitz, Ja., Pitari, G., Reddy, S., Sahu, L., Sakamoto, H., Schuster, G., Schwarz, J. P., Seland, Ø., Spackman, J. R., Stier, P., Takegawa, N., Takemura, T., Textor, C., van Aardenne, J. A., and Zhao, Y.: Evaluation of black carbon estimations in global aerosol models, Atmos. Chem. Phys. Discuss., 9, 15769-15825, doi:10.5194/acpd-9-15769-2009, 2009.
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