Estimating global surface ammonia concentrations inferred from satellite retrievals
Ammonia (NH3), as an alkaline gas in the atmosphere, can cause direct or indirect effects on the air quality, soil acidification, climate change and human health. Estimating surface NH3 concentrations is critically important for modeling the dry deposition of NH3 and for modeling the formation of am...
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Published in | Atmospheric chemistry and physics Vol. 19; no. 18; pp. 12051 - 12066 |
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Main Authors | , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Katlenburg-Lindau
Copernicus GmbH
26.09.2019
Copernicus Publications |
Subjects | |
Online Access | Get full text |
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Summary: | Ammonia (NH3), as an alkaline gas in the atmosphere, can cause direct
or indirect effects on the air quality, soil acidification, climate change
and human health. Estimating surface NH3 concentrations is
critically important for modeling the dry deposition of NH3 and for
modeling the formation of ammonium nitrate, which have important impacts on
the natural environment. However, sparse monitoring sites make it
challenging and difficult to understand the global distribution of surface
NH3 concentrations in both time and space. We estimated the global
surface NH3 concentrations for the years of 2008–2016 using
satellite NH3 retrievals combining vertical profiles from
GEOS-Chem. The accuracy assessment indicates that the satellite-based
approach has achieved a high predictive power for annual surface NH3
concentrations compared with the measurements of all sites in China, the US and
Europe (R2=0.76 and RMSE = 1.50 µg N m−3). The
satellite-derived surface NH3 concentrations had higher consistency
with the ground-based measurements in China (R2=0.71 and RMSE = 2.6 µg N m−3) than the US (R2=0.45 and RMSE = 0.76 µg N m−3) and Europe (R2=0.45 and RMSE = 0.86 µg N m−3) at
a yearly scale. Annual surface NH3 concentrations higher than 6 µg N m−3 are mainly concentrated in the North China Plain of China and
northern India, followed by 2–6 µg N m−3 mainly in southern and
northeastern China, India, western Europe, and the eastern United States (US).
High surface NH3 concentrations were found in the croplands in China, the
US and Europe, and surface NH3 concentrations in the croplands in China
were approximately double those in the croplands in the US and Europe.
The linear trend analysis shows that an increase rate of surface NH3
concentrations (> 0.2 µg N m−3 yr−1) appeared in eastern China during 2008–2016, and a middle increase rate (0.1–0.2 µg N m−3 yr−1) occurred in northern Xinjiang over China. NH3
increase was also found in agricultural regions in the central and eastern US
with an annual increase rate of lower than 0.10 µg N m−3 yr−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. |
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ISSN: | 1680-7324 1680-7316 1680-7324 |
DOI: | 10.5194/acp-19-12051-2019 |