Atmos. Chem. Phys. Discuss., 13, 6247-6294, 2013
© Author(s) 2013. This work is distributed
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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.
Multi-model mean nitrogen and sulfur deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): evaluation historical and projected changes
J.-F. Lamarque1, F. Dentener2, J. McConnell3, C.-U. Ro4, M. Shaw4, R. Vet4, D. Bergmann5, P. Cameron-Smith5, R. Doherty6, G. Faluvegi7, S. J. Ghan8, B. Josse9, Y. H. Lee7, I. A. MacKenzie6, D. Plummer10, D. T. Shindell7, D. S. Stevenson6, S. Strode11,12, and G. Zeng13
1NCAR Earth System Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
2European Commission, Joint Research Centre, Ispra, Italy
3Desert Research Institute, Reno, NV, USA
4Environment Canada, Toronto, Ontario, Canada
5Lawrence Livermore National Laboratory, Livermore, CA, USA
6School of GeoSciences, University of Edinburgh, Edinburgh, UK
7NASA Goddard Institute for Space Studies and Columbia Earth Institute, New York, NY, USA
8Pacific Northwest National Laboratory, Richland, WA, USA
9GAME/CNRM, Météo-France, CNRS – Centre National de Recherches Météorologiques, Toulouse, France
10Canadian Centre for Climate Modeling and Analysis, Environment Canada, Victoria, British Columbia, Canada
11NASA Goddard Space Flight Center, Greenbelt, MD, USA
12Universities Space Research Association, Columbia, MD, USA
13National Institute of Water and Atmospheric Research, Lauder, New Zealand

Abstract. We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice-core measurements. We use a new dataset of wet deposition for 2000–2002 based on critical assessment of the quality of existing regional network data. We show that for present-day (year 2000 ACCMIP time-slice), the ACCMIP results perform similarly to previously published multi-model assessments. For this time slice, we find a multi-model mean deposition of 50 Tg(N) yr−1 from nitrogen oxide emissions, 60 Tg(N) yr−1 from ammonia emissions, and 83 Tg(S) yr−1 from sulfur emissions. The analysis of changes between 1980 and 2000 indicates significant differences between model and measurements over the United States but less so over Europe. This difference points towards misrepresentation of 1980 NH3 emissions over North America. Based on ice-core records, the 1850 deposition fluxes agree well with Greenland ice cores but the change between 1850 and 2000 seems to be overestimated in the Northern Hemisphere for both nitrogen and sulfur species. Using the Representative Concentration Pathways to define the projected climate and atmospheric chemistry related emissions and concentrations, we find large regional nitrogen deposition increases in 2100 in Latin America, Africa and parts of Asia under some of the scenarios considered. Increases in South Asia are especially large, and are seen in all scenarios, with 2100 values more than double 2000 in some scenarios and reaching > 1300 mg(N) m−2 yr−1 averaged over regional to continental scale regions in RCP 2.6 and 8.5, ~30–50 % larger than the values in any region currently (2000). The new ACCMIP deposition dataset provides novel, consistent and evaluated global gridded deposition fields for use in a wide range of climate and ecological studies.

Citation: Lamarque, J.-F., Dentener, F., McConnell, J., Ro, C.-U., Shaw, M., Vet, R., Bergmann, D., Cameron-Smith, P., Doherty, R., Faluvegi, G., Ghan, S. J., Josse, B., Lee, Y. H., MacKenzie, I. A., Plummer, D., Shindell, D. T., Stevenson, D. S., Strode, S., and Zeng, G.: Multi-model mean nitrogen and sulfur deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): evaluation historical and projected changes, Atmos. Chem. Phys. Discuss., 13, 6247-6294, doi:10.5194/acpd-13-6247-2013, 2013.
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