A Decade of Changes in Global SO2 Pollution: Insights from Aura/Ozone Monitoring Instrument

SO₂ is a toxic criteria air pollutant regulated by many environmental agencies around the world and a precursor to sulfate aerosols, a major component in smog and haze that cause an estimated over one million premature deaths each year. To predict and mitigate air pollution, air quality models require accurate information on the emissions of SO₂ and other pollutants. However, conventional bottom-up emission inventories are normally only updated every 3-5 years and this may lead to substantial uncertainties, particularly for developing countries that are experiencing fast-paced changes in economy and/or environmental policies. In this presentation, we show how global SO₂ observations, provided by the Ozone Monitoring Instrument (OMI) aboard the NASA Aura spacecraft since 2004, can help to improve our understanding of SO₂ pollution. In particular, recent advances in the OMI SO₂ data product and a new emissions estimation technique have enabled the development of an independent, top-down, OMI-based SO₂ emission inventory that include ~500 sources worldwide. Analyses of OMI SO₂ retrievals and the derived emissions estimates reveal significant regional trends in SO₂ pollution that are not yet fully captured by bottom-up inventories. One surprising finding from OMI, also supported by aircraft measurements, is a dramatic reduction in SO₂ emissions from China that far exceeds many recent projections. We will discuss the implications of OMI observed changes in SO₂ on air quality and regional climate. We will also discuss important forthcoming updates to the OMI SO₂ product that will enable improved global monitoring and science analyses.