Multi-model study of HTAPÂ II on sulfur and nitrogen deposition
This study uses multi-model ensemble results of 11 models from the second phase of Task Force Hemispheric Transport of Air Pollution (HTAP II) to calculate the global sulfur (S) and nitrogen (N) deposition in 2010. Modeled wet deposition is evaluated with observation networks in North America, Europe and East Asia. The modeled results agree well with observations, with 76â83â¯% of stations being predicted within ±50â¯% of observations. The models underestimate SO42â, NO3â and NH4+ wet depositions in some European and East Asian stations but overestimate NO3â wet deposition in the eastern United States. Intercomparison with previous projects (PhotoComp, ACCMIP and HTAP I) shows that HTPA II has considerably improved the estimation of deposition at European and East Asian stations. Modeled dry deposition is generally higher than the inferential data calculated by observed concentration and modeled velocity in North America, but the inferential data have high uncertainty, too. The global S deposition is 84â¯Tg(S) in 2010, with 49â¯% in continental regions and 51â¯% in the ocean (19â¯% of which coastal). The global N deposition consists of 59â¯Tg(N) oxidized nitrogen (NOy) deposition and 64â¯Tg(N) reduced nitrogen (NHx) deposition in 2010. About 65â¯% of N is deposited in continental regions, and 35â¯% in the ocean (15â¯% of which coastal). The estimated outflow of pollution from land to ocean is about 4â¯Tg(S) for S deposition and 18â¯Tg(N) for N deposition. Comparing our results to the results in 2001 from HTAP I, we find that the global distributions of S and N deposition have changed considerably during the last 10 years. The global S deposition decreases 2â¯Tg(S) (3â¯%) from 2001 to 2010, with significant decreases in Europe (5â¯Tg(S) and 55â¯%), North America (3â¯Tg(S) and 29â¯%) and Russia (2â¯Tg(S) and 26â¯%), and increases in South Asia (2â¯Tg(S) and 42â¯%) and the Middle East (1â¯Tg(S) and 44â¯%). The global N deposition increases by 7â¯Tg(N) (6â¯%), mainly contributed by South Asia (5â¯Tg(N) and 39â¯%), East Asia (4â¯Tg(N) and 21â¯%) and Southeast Asia (2â¯Tg(N) and 21â¯%). The NHx deposition increases with no control policy on NH3 emission in North America. On the other hand, NOy deposition has started to dominate in East Asia (especially China) due to boosted NOx emission.
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https://n2t.org/ark:/85065/d7n87dh4
eng
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2016-01-01T00:00:00Z
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2018-05-16T00:00:00Z
Copyright author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
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