Influence of the Summer Changes in Large-scale Atmospheric Circulation on the Vertical Fluxes of Heat and Moisture in Russian Landscape Zones

Abstract

The summer changes in the vertical heat and moisture fluxes in Russian landscape zones were analyzed in connection with the changes in the indices of the leading modes of general atmospheric circulation, sea surface temperature, and air temperature. The series of the circulation indices and ERA5 and ERA5-Land reanalysis data were used. The contribution of the general circulation modes, sea surface temperature, and air temperature to the changes in heat and moisture fluxes on Russian plain territories can vary from 40 to 90% depending on a landscape zone. The vertical fluxes of heat and moisture in European Russia and Western Siberia are largely dependent on the SCAND and EA/WR regional modes of atmospheric circulation. With a change in the phases of SCAND and EA/WR from positive to negative, a significant increase in the areas of influence of these modes on heat fluxes occurred in subarctic and boreal landscapes, and a decrease in the areas of influence on moisture divergence was registered in boreal and subboreal landscapes. In the summers of 1950–2021, trends in upward sensible heat fluxes were evident in subboreal landscapes of eastern European Russia (4–6%/10 years). The trends in upward latent heat fluxes in subarctic and boreal landscapes of Western Siberia were about 3%, and the ones in downward latent heat fluxes in subboreal landscapes made up about 5%. The trends in upward moisture fluxes in subarctic and northern boreal landscapes were registered at the level of 5–7%, and an increase in downward moisture fluxes by 10% was observed in subboreal landscapes.