Keywords: nitrogen dioxide, carbon monoxide, Sentinel-5P, plume, background content

The full-scale russian invasion of Ukraine significantly changed atmospheric air pollution in Ukrainian cities. Most changes can be identified using only remote sensing data due to its spatial coverage. In the presented paper, we perform the analysis of war impacts on nitrogen dioxide (NO2) and carbon monoxide (CO) spatial distribution derived from the TROPOsphericMOnitoring Instrument (TROPOMI) of the Sentinel-5 Precursor (S5P) satellite data for the period of January 2021 – May 2023. Based on their content in polluted plumes over the city and in the background, the parameter dNO2/dСО for burning efficiency assessment was calculated and processed. The overall decrease in NO2 and CO content was detected in the cities, reaching 6-34% and 9-17%, respectively. In comparison to background content, the NO2 drop in cities was more significant. At the same time, CO decreased by 2-3% more in the background than over the cities (except Mariupol, where Azovstal was totally destroyed). Since the full-scale hostilities have started, total NO2 content began redistributing seasonally and its summer maxima started to appear in the majority of cities. Starting from the period of regular drone and missile attacks on energy infrastructure, background NO2 significantly decreased, showing a regional response. CO total content has changed mostly homogeneously over the entire studied domain. There were no seasonal shifts or dependencies during the period of war. Using the four parameters mentioned, we estimated burning efficiency changes based on the dNO2/dСО parameter. It allowed us to detect possible changes in fuel use. Overall, dNO2/dСО decreased by 11-46% which indirectly proved the increase in solid or “dirty” fuel use and less gas consumption. Burning efficiency dropped immediately after the full-scale invasion started, becoming more sensitive to pollutants content in the plume. The consideration of the researched parameters is important for making new atmospheric air quality management plans in cities, rebuilding damaged infrastructure, and creating emission inventories during the wartime.

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