Atmos. Chem. Phys. Discuss., 8, 8385-8429, 2008
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A multi-model assessment of pollution transport to the Arctic
D. T. Shindell1, H. Teich1, M. Chin2, F. Dentener3, R. M. Doherty4, G. Faluvegi1, A. M. Fiore5, P. Hess6, I. A. MacKenzie4, M. G. Sanderson7, M. G. Schultz8, M. Schulz9, D. S. Stevenson4, C. Textor9, O. Wild10, D. J. Bergmann11, H. Bian12, C. Cuvelier3, B. N. Duncan12, G. Folberth13, L. W. Horowitz5, J. Jonson14, J. W. Kaminski15, E. Marmer3, R. Park16, K. J. Pringle7,*, S. Schroeder8, S. Szopa9, T. Takemura17, G. Zeng18, T. J. Keating19, and A. Zuber20
1NASA Goddard Institute for Space Studies and Columbia University, New York, NY, USA
2NASA Goddard Space Flight Center, Greenbelt, MD, USA
3European Commission, Institute for Environment and Sustainability, Joint Research Centre, Ispra, Italy
4School of GeoSciences, University of Edinburgh, UK
5Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ, USA
6National Center for Atmospheric Research, Boulder, CO, USA
7Met Office Hadley Centre, Exeter, UK
8ICG-2, Forschungszentrum-J ¨ ulich, Germany
9Laboratoire des Science du Climat et de l’Environnement, Gif-sur-Yvette, France
10Department of Environmental Science, Lancaster University, UK
11Atmospheric Science Division, Lawrence Livermore National Laboratory, CA, USA
12Goddard Earth Science and Technology Center, U. Maryland Baltimore County, MD, USA
13Laboratoire de Mod´ elisation de la Chimie Atmosph´ erique, Ecole Polytechnique F´ed´ erale de Lausanne, Lausanne, Switzerland
14Norwegian Meteorological Institute, Oslo, Norway
15Center for Research in Earth and Space Science, York University, Canada
16Atmospheric Chemistry Modeling Group, Harvard University, Cambridge, MA, USA and School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
17Research Institute for Applied Mechanics, Kyushu University, Japan
18National Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Cambridge, UK
19Office of Policy Analysis and Review, Environ. Protection Agency, Washington DC, USA
20Environment Directorate General, European Commission, Brussels, Belgium
*now at: Max Planck Institute for Chemistry, Mainz, Germany

Abstract. We examine the response of Arctic gas and aerosol concentrations to perturbations in pollutant emissions from Europe, East and South Asia, and North America using results from a coordinated model intercomparison. These sensitivities to regional emissions (mixing ratio change per unit emission) vary widely across models and species. Intermodel differences are systematic, however, so that the relative importance of different regions is robust. North America contributes the most to Arctic ozone pollution. For aerosols and CO, European emissions dominate at the Arctic surface but Asian emissions become progressively more important with altitude, and are dominant in the upper troposphere. Sensitivities show strong seasonality: surface sensitivities typically maximize during boreal winter for European and during spring for East Asian and North American emissions. Mid-tropospheric sensitivities, however, nearly always maximize during spring or summer for all regions. Deposition of black carbon (BC) onto Greenland is most sensitive to North American emissions. North America and Europe each contribute ~40% of total BC deposition to Greenland, with ~20% from East Asia. Elsewhere in the Arctic, both sensitivity and total BC deposition are dominated by European emissions. Model diversity for aerosols is especially large, resulting primarily from differences in aerosol physics and removal. Comparison of aerosols with observations indicates problems in either the models or interpretation of the measurements. For gas phase pollutants such as CO and O3, which are relatively well-simulated, the processes contributing most to uncertainties depend on the source region. Uncertainties in the Arctic surface CO response to emissions perturbations are dominated by emissions for East Asian sources, while uncertainties in transport, emissions, and oxidation are comparable for European and North American sources. At higher levels, model-to-model variations in transport and oxidation are most important. Differences in photochemistry appear to play the largest role in the intermodel variations in Arctic ozone sensitivity.

Citation: Shindell, D. T., Teich, H., Chin, M., Dentener, F., Doherty, R. M., Faluvegi, G., Fiore, A. M., Hess, P., MacKenzie, I. A., Sanderson, M. G., Schultz, M. G., Schulz, M., Stevenson, D. S., Textor, C., Wild, O., Bergmann, D. J., Bian, H., Cuvelier, C., Duncan, B. N., Folberth, G., Horowitz, L. W., Jonson, J., Kaminski, J. W., Marmer, E., Park, R., Pringle, K. J., Schroeder, S., Szopa, S., Takemura, T., Zeng, G., Keating, T. J., and Zuber, A.: A multi-model assessment of pollution transport to the Arctic, Atmos. Chem. Phys. Discuss., 8, 8385-8429, doi:10.5194/acpd-8-8385-2008, 2008.
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