Inverse Estimation of SO2 Emissions over China with Local Air Mass Factor Applied

Abstract:

Sulfur dioxide (SO₂) has significant impacts on human health as it forms sulfate aerosols in the atmosphere. Widespread uncertainty in the magnitude of SO₂ emissions hinders efforts to address this issue. In this work we use Ozone Monitoring Instrument (OMI) slant column SO₂ observations as constraints to conduct inversion of SO₂ emissions over China for April 2008. Local air mass factors are formulated as the integral of the relative vertical distribution of SO₂ simulated from GEOS-Chem, weighted by scattering weights computed from VLIDORT. They are applied to convert slant column to vertical column GEOS-Chem SO₂. After data assimilation SO₂ emissions decrease in Sichuan Basin, South China, and most areas of North China. The posterior SO₂ emissions are evaluated with in situ SO₂ observation. Besides, we apply the posterior SO₂ emissions of April 2008 to April 2009, and it leads to improved agreement of modeled SO₂ to the OMI observations. This offers potential to update SO₂ emissions in real time.