Changes in Precipitation Characteristics over Russia in the 20th and 21st Centuries According to CMIP6 Model Ensemble Data

A study has been made of changes in some characteristics of daily precipitation in Russia for the winter and summer seasons in the 20th and 21st centuries using Coupled Model Intercomparison Project Phase 6 (CMIP6) climate models. In the modern period, model data are compared with data from meteorological stations and ERA5 reanalysis. For winter and summer, changes in mean seasonal precipitation, the number of days with precipitation, and the frequency of extreme precipitation are analyzed. For the modern period 1991-2020, according to empirical data, in winter on the territory of Russia, a significant increase in seasonal precipitation amounts and the frequency of days with extreme precipitation on the Far East coast and in the central part of European Russia (ER) are detected. A decrease in the frequency of days with precipitation at most meteorological stations in Russia by 4-6 days/10 years is also noted. In summer, an increase in precipitation amounts and the frequency of days with precipitation is found in Western Siberia and on the coasts of the Sea of Okhotsk and the Pacific Ocean. A decrease in the amount and frequency of precipitation is obtained for southern ER and the south of Eastern Siberia. Climate models, on average for the ensemble, show an increase in the relative amounts of precipitation and the extreme precipitation frequency over most of the Russia territory in winter, and these trends may intensify in the coming decades. In summer, on the contrary, for southern ER, as a whole, there is a slight decrease in the seasonal precipitation totals and the number of days with precipitation. However, strong intermodel differences, especially in the summer season, do not allow us to draw unambiguous conclusions about changes in precipitation characteristics in Russia in the next 30 years. By the end of the 21st century, changes will become more pronounced. For example, in ER and northern Siberia, a noticeable increase in winter precipitation amounts and the frequency of extreme precipitation may occur. By the end of the 21st century, a slight decrease in the precipitation totals and the number of days with precipitation is possible in summer in ER.