Isotopic Composition of Tropospheric Water Vapor in the Vicinity of St. Petersburg

Water vapor plays a key role in different climate-forming processes at various altitudes in the Earth’s atmosphere. Monitoring of water vapor isotopologues provides information on the atmospheric hydrological cycle. It helps to study the processes associated with evaporation and condensation which control the moisture in the troposphere and the troposphere–stratosphere water exchange. The temporal variability of water vapor isotopologues (H₂O and δD) in Peterhof in 2009–2020 is analyzed for the first time on the basis of ground-based Bruker IFS 125HR Fourier spectrometer measurements of solar IR radiation. For both H₂O and δD, the maxima occur in summer and the minima in winter; the largest variability of H₂O is observed in summer, and of δD, in winter months due to the climatic features of St. Petersburg, i.e., the origin and history of incoming air masses. The database of water vapor isotopic composition in the vicinity of St. Petersburg can be used in models of the general circulation of the atmosphere to improve the accuracy of weather forecasting and long-term changes in the regional climate.