Global gridded NO_x emissions using TROPOMI observations

Abstract. We present top-down global gridded emissions of NO_x for the year 2022. This dataset is constructed from retrievals of tropospheric vertical column densities of NO₂ by the TROPOMI spaceborne instrument associated with winds and atmospheric composition data from ECMWF reanalyses, using an improved version of a mass-balance atmospheric inversion. The emissions are provided with a spatial resolution of 0.0625°×0.0625° and deliver a detailed overview of the distribution of emissions. They allow the identification of intense area sources and isolated emitters, and the quantification of their associated emissions. At global level, the emissions obtained are consistent with the EDGARv6.1 bottom-up inventory, although there are differences at regional level, particularly in emerging countries and countries with low observation densities. The three largest emitting countries, China, the United States and India, are 11, 16 and 6 % lower than EDGAR estimates. Uncertainties remain high, and a quantitative analysis of emissions over several averaging periods indicates that averaging emissions uniformly across the year may be sufficient to obtain estimates consistent with annual averages, in regions of the world with high retrieval densities. This dataset is designed to be updated with a low latency to help policymakers monitor emissions and implement energy savings and clean air quality policies. The data can be accessed at https://doi.org/10.5281/zenodo.13957837 as monthly files (Rey-Pommier et al., 2024).