OMI satellite observations of decadal changes in ground-level sulfur dioxide over North America

Abstract. Sulfur dioxide (SO₂) has a significant impact on the environment and human health. We estimated ground-level sulfur dioxide (SO₂) concentrations from the Ozone Monitoring Instrument (OMI) using SO₂ profiles from the Global Environmental Multi-scale – Modelling Air quality and CHemistry (GEM-MACH) model over North America for the period of 2005–2015. OMI-derived ground-level SO₂ concentrations (r = 0. 61) and trends (r = 0. 74) correlated well with coincident in situ measurements from air quality networks over North America. We found a strong decreasing trend in coincidently sampled ground-level SO₂ from OMI (−81 ± 19 %) and in situ measurements (−86 ± 13 %) over the eastern US for the period of 2005–2015, which reflects the implementation of stricter pollution control laws, including flue-gas desulfurization (FGD) devices in power plants. The spatially and temporally contiguous OMI-derived ground-level SO₂ concentrations can be used to assess the impact of long-term exposure to SO₂ on the health of humans and the environment.