Hao Kong1, Jintai Lin1, *, Lulu Chen1, Yuhang Zhang1, Yingying Yan2, Mengyao Liu3, Ruijing Ni1, Zhehui Liu1, Hongjian Weng`1
1Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China
2Department of Atmospheric Science, School of Environmental Sciences, China University of Geosciences, Wuhan, 430074, China
3R&D Satellite Observations Department, Royal Netherlands Meteorological Institute, De Bilt, NL-3731 GA, the Netherlands
High-resolution (e.g., 5 km) emission data of nitrogen oxides (NOx = NO + NO2) provide localized knowledge of pollution sources for targeted regulations, yet such data are lacking or inaccurate over most regions at present. Here we improve our PHLET-based inversion method to derive NOx emissions in China at a 5-km resolution in summer 2019, based on the TROPOMI-POMINO satellite product of nitrogen dioxide (NO2) columns. With low computational costs, our inversion explicitly accounts for the effects of horizontal transport and nonlinear chemistry. We find numerous small-to-medium sources related to minor roads and small human settlements at relatively low affluence levels, in addition to clear emission signals along major transportation lines, consistent with road line density and Tencent location data. Many smallto-medium sources and transportation emissions are unclear or missing in the spatial distributions of four widely used emission inventories. Our emissions offer a unique reference for targeted emission control.