Weekly Cycle of Pollutant Concentrations in Near-Surface Air over Moscow

Abstract

Time variations in the concentrations of gas pollutants CO, NO, NO₂, SO₂, and PM₁₀ aerosol in the surface atmospheric layer over Moscow show a weekly cycle, manifested as a decrease in the pollution level on weekends. The character of the weekly variations and amplitude of the weekly cycle were determined using, for the first time, a 10-year archive of observations of atmospheric composition from 46 State Nature Conservation Organization (SNCO) Mosecomonitoring stations. The amplitudes of weekly oscillations in the daytime CO concentration, averaged over the territory of the city and seasons, vary from 21.8% in spring to 29.2% in winter, and those of daytime NO concentration vary from 16.9% in summer to 38.1% in winter. The weekly cycle of daytime NO₂ concentration is stable throughout the year, and its amplitude is 33% on average. Amplitudes of weekly variations in SO₂ and PM₁₀ (22.7% and 35.2%, respectively) are maximal in autumn according to daytime data; the CH₄ weekly cycle is insignificant. In nighttime concentrations of these pollutants, a significant weekly cycle is extracted only for NO₂. The analysis of the data, obtained for separate Moscow districts, shows approximately the same Sunday effect. Only CO concentrations have high amplitudes at the city center (39.2%) and in the southwestern sector (35.1%).