Improved catalog of NO_x point source emissions (version 2)

Abstract. We present an updated (v2) catalog of NO_x emissions from point sources as derived from TROPOMI measurements of NO₂ (PAL product) combined with wind fields from ERA5. Compared to version 1 of the catalog, several improvements have been introduced to the algorithm. Most importantly, several corrections are applied, accounting for the effects of plume height on satellite sensitivity, 3D topographic effects, and the chemical loss of NO_x, resulting in considerably higher and more accurate NO_x emissions. In addition, error estimates are provided for each point source, taking into account the uncertainties of the individual retrieval steps.

The catalog v2 is based on a fully automated iterative detection algorithm of point sources worldwide. It lists 1139 locations that have been found to be significant NO_x sources. The majority of these locations match to power plants listed in the global power plant database (GPPD). Other NO_x point sources correspond to cement plants, metal smelters, industrial areas, or medium-sized cities.

The emissions listed in v2 of the catalog show good agreement (within 20 % on average) to emissions reported by German Environment Agency (Umweltbundesamt, UBA) as well as the United States Environmental Protection Agency (EPA). The data is publically available at https://doi.org/10.26050/WDCC/No_xPointEmissionsV2 (Beirle et al., 2023).