Atmospheric transport of dust aerosol from arid zones to the Moscow region during fall 2020

Abstract

<abstract> <p>We analyzed the unique episode of long-range dust/sand atmospheric aerosol transport from the arid zones of the southern European territory of Russia, i.e. the Northern Caspian and Astrakhan regions and the Kalmykia Republic, to the Moscow region during fall 2020. Intensive complex experiments were carried out at the A.M. Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciencesin the center of Moscow through different seasons during 2020–2021 to study the composition of near-surface aerosols in the Moscow megacity. The experimental data are considered to take into account the synoptic features and meteorological conditions. Abnormally high values of near-surface aerosol mass concentrations in Moscow were registered during the period from 6 to 14 of October 2020 under stable anti-cyclonic conditions, with calm or quiet/light wind (1–2 m/s), and under the conditions of the dominance of southeastern air mass transport. At the same time, the average daily mass concentration of aerosol particles PM₁₀ exceeded the Maximum Permissible Concentration (MPC) value (60 µg/m³) by 1.5–4.5 times, and the number of large (micron) particles increased by an order or more. Comparative analysis of aerosol elemental composition in Moscow (during this episode) and in Kalmykia (according to observations in July 2020) showed high correlation for terrigenous elements' patterns. The aerosol origin for this episode was confirmed by performing long-range trajectory analysis of air mass transport (HYSPLIT model), and by using MERRA-2 reanalysis data for dust aerosol spatial distribution.</p> </abstract>