LAUSR

Abstract GRIMM aerosol spectrometer measurements of mass concentrations of PM1, PM2.5, and PM10 near St. Petersburg (Russia) in 2016–2018 are analyzed. The average concentrations of PM1, PM2.5, and PM10 over the measurement period are 4.5, 4.8, and 4.9 μg/m 3 , respectively. The hourly average PM10 concentrations are compared with the aerosol optical thickness at a wavelength of 500 nm (AOT) for different seasons. The correlation between the PM10 concentration and AOT is found to be the strongest in autumn. According to the distribution of the wind directions, the maximal PM10 concentrations correspond to the eastern winds (from St. Petersburg). The seasonal dependence of the daily variation in the mass concentration of PM10 on the relative air humidity and the height of the atmospheric boundary layer is analyzed. The PM10 concentrations (~8 μg/m 3 on the average) and the amplitude of their daily variations are maximal in winter.