Long-Term Tendencies and Variability of CO content in the Atmosphereof the Moscow Megapolis

This report presents the results of a comprehensive analysis of spectroscopic long-term data sets on CO total content (CO TC) at stations of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS), in Moscow and Moscow oblast. The long-term variability of CO TC and meteorological parameters in atmospheric boundary layer were investigated. A decrease in the average TC CO annual values in 2000–2023 was found for Moscow (–2.23 ± 0.36%/year) and for Zvenigorod Scientific Station (ZSS) (‒1.12 ± 0.33%/year). The CO trend characteristics in both sites in different seasons and periods are demonstrated and discussed.After about 2007–2008, the rate of CO TC reduction decreased at both sites. In 2008–2023 at the ZSS no significant changes in CO TC in the summer and autumn months were found: trend was near zero (-0.04±0.81%/year). An increase in the wind speed in the atmospheric boundary layer of Moscow in different periods of 2008–2022 at a rate of 0.66±0.55%/year has been determined. At the same time, no statistically significant changes in wind speed were found in Kaluga oblast (0.12±0.56%/year). The results indicate the influence of the climatic (meteorological) factor on air quality in Moscow.Study was supported by Russian Science Foundation, Project No 20-17-00200.