Analysis of the increasing trend of NH3 over East Asia during 2011-2019

The rapid economic development of East Asia has contributed to the rapid increase in air pollutant emissions, which results in the governments of each country implementing emission control policies. Accordingly, reductions in emissions and concentrations of major precursor gases such as sulfur dioxide (SO2) and nitrogen dioxide (NO2) have been reported in recent studies. However, the concentration of ammonia (NH3), another major precursor gas, has been shown to increase. In this study, we discuss the increasing pattern of NH3 different from other air pollutants through several approaches. To investigate the trends of precursor gases and aerosol optical depth over East Asia, Geostationary Ocean Color Imager (GOCI) Aerosol optical depth (AOD) at 550nm, Ozone Monitoring Instrument (OMI) SO2, OMI tropospheric NO2, and Infrared Atmospheric Sounding Interferometer (IASI) NH3 from March 2011 to February 2019 are used in this study. To interpret the change in concentration of air pollutants in terms of emissions, a multiple linear regression model was constructed to eliminate the change due to meteorology. The increased NH3 can result from an increased emission of NH3, a reduction of PM2.5 formation, or a change in physiochemical properties. To demonstrate this analysis, the other satellite observations of NH3 and inventories of NH3 emissions were utilized.