Effect of Meteorological Conditions and Long-Range Air Mass Transport on Surface Aerosol Composition in Winter Moscow.

We discuss the results from the complex experiment aimed at studying the composition and time variations in urban aerosol in the surface air at the center of Moscow based on daily data on PM₁₀ and PM_2.5 concentrations. In addition to these continuous observations every season (for 35–40 days), the total aerosol mass concentration (by gravimetric method) and 65 chemical elements in aerosol composition were measured daily. Winters 2019/2020 and 2020/2021 are considered. The aerosol composition is juxtaposed to the meteorological parameters in the surface atmosphere in Moscow, the direction of long-range air mass transport toward the Moscow region, and the distribution of dust in air over the European Russia (using the MERRA-2 reanalysis data). The detailed analysis of the aerosol elemental composition in Moscow made it possible to identify the elements of global/local spread, as well as of natural/anthropogenic genesis. Concentrations of all aerosol constituents in Moscow during winter did not exceed the corresponding daily average MPC values for the air of residential territories. It is shown that the accumulation of PM₁₀ and PM_2.5 in urban air was favored by calm weather conditions. The maximal levels of aerosol pollution were observed in December 2020 during southeasterly winds, when long-range atmospheric transport of admixtures to Moscow occurred from sources located in the southern regions of European Russia, the Caspian Depression, and western Kazakhstan. [ABSTRACT FROM AUTHOR]