Comparison of TROPOMI NO2, CO, HCHO, and SO2 data against ground‐level measurements in close proximity to large anthropogenic emission sources in the example of Ukraine

Abstract

AbstractThe TROPOspheric Monitoring Instrument (TROPOMI) significantly improved the quality of air pollution monitoring. The comparison against other data sources showed acceptable results and good correlation. However, highly polluted areas remain the reason for large uncertainties. In our study, we compared TROPOMI NO2, CO, HCHO, and SO2 data against ground‐level measurements from Ukrainian monitoring sites, which could be considered rather unusual due to their close location to large anthropogenic emission sources. These sites were established in the former USSR to reflect the maximal air pollution levels. TROPOMI detected all cities with huge anthropogenic emissions in 2019–2020 and qualitatively reflected air pollution in Ukraine. However, direct comparison against individual monitoring sites showed mainly insignificant correlation, which was not much improved with cloudiness filtering, spatial averaging, and considering boundary layer height. We show that on an hour‐to‐daily scale, differences appear when remote sensing at a particular time cannot catch the elevated pollution levels in the boundary layer after air mass transportation. On a seasonal scale, the correlation decreases because of the differences in seasonality between near‐surface and column pollutants' content. We discuss that the relationship between TROPOMI and ground‐level measurements depends on the season, the continuance of industrial emissions, and the features of individual emission sources.