Variability of Nitrogen Oxides in the Atmospheric Surface Layer near Saint Petersburg

D. V. Ionov and A. V. Poberovskii

The results of measurements of surface concentrations of nitrogen oxides NOx (NO and NO2) performed at the atmospheric monitoring station near Saint Petersburg (Petergof, 59.88 N, 29.83 E) in 2012–2018 are presented. The main patterns of the temporal variability of NOx concentrations typical for the urban atmosphere of a large megacity (seasonal, daily, and weekly variations) are revealed. On average, NOx concentrations in summer are lower than in the cold season. The average daily variations are characterized by two pronounced peaks: in the morning and late at night, which are separated by the periods of relatively low concentrations during the day and early in the morning. The weekly variations in NOx concentration due to the cyclic pattern of urban economic and business activity are manifested in a noticeable decrease in the average NOx concentration on Sunday relative to its maximum level on weekdays (by 17% for NO2 and by 33% for NO). Based on the distribution of the average NOx concentration depending on the directions of surface wind, a rough estimate of the average NO2 concentration in Saint Petersburg was obtained: 41 g/m3, which is close to the average annual maximum permissible concentration (40 g/m3).