Sulfur dioxide (SO2) trends over the urban regions of China during 2007–2020 using MERRA-2 and CAMSRA

Sulfur dioxide (SO₂) plays a key role in the formation of atmospheric sulfate that can adversely affect urban environment, human health, air quality, and the Earth’s climate system. In this talk, we present results of SO₂ trends over the 4 urban regions (YRD, BTH, PRD, and SCB) of China during 2007-2020, using the SO₂ massconcentrations of the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), and the SO₂ total column of Copernicus Atmosphere Monitoring Service Reanalysis (CAMSRA). The SO₂ concentration decreased significantly during 2007-2020 over the 4 regions: YRD, BTH, PRD, and SCB, with the rate of -0.04 µg.m^-3 per year, -0.05 µg.m^-3 per year, -0.01 µg.m^-3per year, and -0.03 µg.m^-3 per year, receptively. Using CAMSRA data, total column of SO₂ also experienced significant decreasing trends during 2007-2020 over YRD, PRD, and SCB, with the rate of -0.15 mg.m^-2 per year, -0.05 mg.m^-2 per year, and -0.06 mg.m^-2 per year, receptively. The decreasing SO₂ levels after 2007 were mainly attributed to Chinese air pollution control policies. This work contributes to a better understanding of the impact of Chinese policies on the SO₂ level over the urban regions of China.