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- Title
Estimating global surface ammonia concentrations inferred from satellite retrievals.
- Authors
Lei Liu; Xiuying Zhang; Wong, Anthony Y. H.; Wen Xu; Xuejun Liu; Yi Li; Huan Mi; Xuehe Lu; Limin Zhao; Zhen Wang; Xiaodi Wu
- Abstract
Ammonia (NH3), as an alkaline gas in the atmosphere, can cause direct or indirect effects on the air quality, soil acidification, climate change as well as human health. Estimating surface NH3 concentrations is critically important for modelling the dry deposition of NH3, which has important impacts on the natural environment. However, sparse monitoring sites make it challenging and difficult to understand the global distribution of surface NH3 concentrations both in time and space. We estimated the global surface NH3 concentrations for the years of 2008-2016 using the satellite NH3 observations combining its vertical profiles from the GEOS-Chem. The accuracy assessment indicates that the satellite-based approach has achieved a high predictive power for annual surface NH3 concentrations (R²=0.76 and RMSE=1.50μgNm-3). The satellite-derived surface NH3 concentrations had higher consistency with the ground-based measurements in China (R²=0.71 and RMSE=2.6μgNm-3) than the US (R²=0.45 and RMSE=0.76μgNm-3) and Europe (R²=0.45 and RMSE=0.86μgNm-3) at a yearly scale. Annual surface NH3 concentrations higher than 6μgNm-3 are mainly concentrated in the North China Plain of China and Northern India, followed by 2-6μgNm-3 mainly in southern and northeastern China, India, western Europe and eastern United States (US). High surface NH3 concentrations were found in the croplands in China, US and Europe, and surface NH3 concentrations in the croplands in China were approximately double than those in the croplands in the US and Europe. The liner trend analysis shows that a significant increase rate of surface NH3 concentrations (>0.2μgNm-3y-1) appeared in the eastern China during 2008-2016, and a middle increase rate (0.1-0.2μgNm-3y-1) occurred in northern Xinjiang over China. NH3 increase was also found in agricultural regions in middle and eastern US with an annual increase rate of lower than 0.10μgNm-3y-1. The satellite-derived surface NH3 concentrations help us to determine the NH3 pollution status in the areas without monitoring sites and to estimate the dry deposition of NH3 in the future.
- Subjects
CHINA; EUROPE; INDIA; SOIL acidification; OCEAN acidification; AMMONIA; TREND analysis; AIR quality
- Publication
Atmospheric Chemistry & Physics Discussions, 2019, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acp-2019-184