Analysis of Observation Data on Carbon Dioxide Concentration in the Atmospheric Surface Layer at Two Monitoring Stations in the Vicinity of Saint Petersburg

The paper presents the results of analyzing the data of continuous precision measurements for carbon dioxide concentrations in the atmospheric surface layer at two stations in the vicinity of Saint Petersburg. The distribution of the difference in the concentrations $$\Delta\mathrm{CO}_{2}$$ at two stations depending on wind speed and wind direction has been obtained. At wind speeds from 1.5 to 3 m/s and the transport from the city, the observed values of $$\Delta\mathrm{CO}_{2}$$ on average reach $$\sim8$$ ppm. The number of cases potentially suitable for assessing integral CO2 emissions from the city’s territory with a duration of at least 3 hours each and $$\Delta\mathrm{CO}_{2}\ge2$$ ppm over the period from August 2023 to October 2024 was equal to 195 and 111 for Voeikovo (wind direction is 202°–295°) and Peterhof (45°–135°), respectively. The differences in the daily dynamics of CO2 at the stations are largely caused by urban effects. The range of diurnal variations in CO2 in summer is 22–31 ppm and decreases to 5–11 ppm in spring and autumn. In winter, under conditions of intense mixing, the diurnal variations are poorly pronounced. The results of the study are necessary for assessing integral CO2 emissions from the territory of Saint Petersburg.