Comparison of Nitrogen and Sulfur Dioxide Concentrations in the Atmosphere of Moscow and Saint Petersburg According to Satellite and Ground-Based Data

Nitrogen and sulfur dioxides are among key atmospheric pollutants and belong to the 3rd class of hazard. Their joint effect on air quality is extremely negative. Monitoring their content in atmospheric air is an urgent environmental problem. Joint analysis and comparison of nitrogen and sulfur dioxide concentrations in air of Moscow and Saint Petersburg (Russia) on the basis of ground-based measurements in 2002–2023 and the tropospheric content of these aerotoxicants based on satellite observation (OMI spectrometer onboard Aura satellite) in 2005–2023 are performed. The concentrations of nitrogen dioxide slowly decrease in Moscow and Saint Petersburg both in satellite and ground-based data. The concentrations of sulfur dioxide significantly decrease in Moscow and Saint Petersburg according to ground-based measurements, while satellite observations show its concentrations to be relatively constant in Saint Petersburg and growing in Moscow. The hypothesis which explains the difference between the ground-based and satellite data on sulfur dioxide is suggested. The results can be used by environmental authorities of Moscow and Saint Petersburg in their practical work.