Updated SO₂ emission estimates over China using OMI/Aura observations

Abstract. The main aim of this paper is to update existing sulfur dioxide (SO₂) emission inventories over China using modern inversion techniques, state-of-the-art chemistry transport modelling (CTM) and satellite observations of SO₂. Within the framework of the EU Seventh Framework Programme (FP7) MarcoPolo (Monitoring and Assessment of Regional air quality in China using space Observations) project, a new SO₂ emission inventory over China was calculated using the CHIMERE v2013b CTM simulations, 10 years of Ozone Monitoring Instrument (OMI)/Aura total SO₂ columns and the pre-existing Multi-resolution Emission Inventory for China (MEIC v1.2). It is shown that including satellite observations in the calculations increases the current bottom-up MEIC inventory emissions for the entire domain studied (15–55° N, 102–132° E) from 26.30 to 32.60 Tg annum⁻¹, with positive updates which are stronger in winter ( ∼  36 % increase). New source areas were identified in the southwest (25–35° N, 100–110° E) as well as in the northeast (40–50° N, 120–130° E) of the domain studied as high SO₂ levels were observed by OMI, resulting in increased emissions in the a posteriori inventory that do not appear in the original MEIC v1.2 dataset. Comparisons with the independent Emissions Database for Global Atmospheric Research, EDGAR v4.3.1, show a satisfying agreement since the EDGAR 2010 bottom-up database provides 33.30 Tg annum⁻¹ of SO₂ emissions. When studying the entire OMI/Aura time period (2005 to 2015), it was shown that the SO₂ emissions remain nearly constant before the year 2010, with a drift of −0.51 ± 0.38 Tg annum⁻¹, and show a statistically significant decline after the year 2010 of −1.64 ± 0.37 Tg annum⁻¹ for the entire domain. Similar findings were obtained when focusing on the greater Beijing area (30–40° N, 110–120° E) with pre-2010 drifts of −0.17 ± 0.14 and post-2010 drifts of −0.47 ± 0.12 Tg annum⁻¹. The new SO₂ emission inventory is publicly available and forms part of the official EU MarcoPolo emission inventory over China, which also includes updated NO_x, volatile organic compounds and particulate matter emissions.