Estimation of surface ammonia concentrations and emissions in China from the polar-orbiting Infrared Atmospheric Sounding Interferometer and the FY-4A Geostationary Interferometric Infrared Sounder

Abstract

Abstract. Ammonia (NH3) is the most important alkaline gas in the atmosphere, which has negative effects on biodiversity, ecosystems, soil acidification and human health. China has the largest NH3 emissions globally, mainly associated with agricultural sources including nitrogen fertilizer and livestock. However, there is still a limited number of ground monitoring sites in China, hindering our understanding of both surface NH3 concentrations and emissions. In this study, using the polar-orbiting satellite (Infrared Atmospheric Sounding Interferometer – IASI) and Fengyun-4A Geostationary Interferometric Infrared Sounder (GIIRS), we analyzed the changes in hourly NH3 concentrations and estimated surface NH3 concentrations and NH3 emissions in China. GIIRS-derived NH3 concentrations in the daytime were generally higher than those at night, with high values during 10:00–16:00 local time. Satellite-derived surface NH3 concentrations were generally consistent with the ground observations, with R-square at 0.72 and slope equal to 1.03. Satellite-based NH3 emissions ranged from 12.17 to 17.77 Tg N yr−1 during 2008–2019. Spatially, high values of NH3 emissions mainly occurred in the North China Plain, Northeast China and the Sichuan Basin, while low values were mainly distributed in West China (Qinghai–Tibet Plateau). Our study shows a high predictive power of using satellite data to estimate surface NH3 concentrations and NH3 emissions over multiple temporal and spatial scales, which provides an important reference for understanding NH3 changes over China.

Trends in anthropogenic ammonia emissions in China since 1980: A review of approaches and estimations

“…Some studies show a higher emission intensity in NCP, eastern and Sichuan basin compared to other regions (MEIC and REAS). This is similar to spatial distribution derived by IASI, and satellitebased studies also show a high spatial variation and hotspot areas (Chen et al, 2020;Liu et al, 2022b). Other datasets show a more uniform distribution in most areas in China (EDGAR and CEDS).…”

“…These features coincide with seasonal distributions based on studies using an inversion model approach (Paulot et al, 2014;Kong et al, 2019;Evangeliou et al, 2021). The satellite-based monthly spatial distribution in China from (Liu et al, 2022b) show that high NH 3 emissions in North China Plain (NCP) occur in June and July.…”

“…Zhang et al (2018) optimized Chinese NH 3 emissions by assimilating TES satellite observations of NH 3 column concentration for March-October 2008. A state-of-the-art study reported long-term IASI-derived NH 3 emission in China by the mass-balance method (Liu et al, 2022b). This mass-balance method was used to exploit the ratio of NH 3 emissions to NH 3 concentrations.…”

Separating Daily 1 km PM2.5 Inorganic Chemical Composition in China since 2000 via Deep Learning Integrating Ground, Satellite, and Model Data

“…The high temperature and stronger radiation also significantly enhance the chemical conversion from SO 2 to SO 4 2– . ,, NO 3 – accounts for 19.8% of the total PM 2.5 but has opposite seasonal changes to that of SO 4 2– , with the lowest value in summer (15%) and higher values in cold seasons in eastern China (Figure ). This is explained by lower temperatures and more available NH 3 -neutralizing sulfates that favor nitrate aerosol partitioning. , The annual NH 4 + fraction is 13.9% in eastern China, showing a weaker seasonal contrast, with a somewhat higher value of ∼14% in summer, presumably due to higher NH 3 emissions from agricultural sources. , NH 4 + resides mostly in the form of ammonium sulfate in summer but in ammonium nitrate in winter . Annual and seasonal Cl – -to-PM 2.5 ratios are much smaller (average = 3–4.6%) than those of the other three inorganic species.…”

“…61,70 The annual NH 4 + fraction is 13.9% in eastern China, showing a weaker seasonal contrast, with a somewhat higher value of ∼14% in summer, presumably due to higher NH 3 emissions from agricultural sources. 62,71 NH 4 + resides mostly in the form of ammonium sulfate in summer but in ammonium nitrate in winter. 61 Annual and seasonal Cl − -to-PM 2.5 ratios are much smaller (average = 3−4.6%) than those of the other three inorganic species.…”