Climatic Shift in the Hydrometeorological Regime of the Sea of Azov and the Caspian Sea

This study is devoted to an analysis of the spatiotemporal variability of the hydrometeorological regime and hydrometeorological hazards (HH) and their combinations in the Sea of Azov and the Caspian Sea for 1950–2020. The current dynamics of the processes are assessed against the background of climatic fluctuations. Based on observation data and mathematical modeling results, an analysis of the air temperature, ice cover and duration of the ice season, and interannual dynamics of wind waves and storm activity is carried out. It is shown that, since 1975, a steady increase in the sum of air temperatures and an increase in the frequency of mild winters have been observed for both water areas. Since the early 1990s, a significant reduction in ice cover and duration of the ice season occurring with varying intensity has been established at all coastal hydrometeorological stations (HMSs). Thus, the ice regime of the seas has been characterized by a change in the characteristics since the early 1990s. For wind waves, the study reveals a shift in the period of maximum wave development to the summer–autumn period after 2000 and an increase in maximum wave heights since the 2010s. In the regions of the Sea of Azov and the Caspian Sea, a decrease in the duration of winter HHP and hydrometeorological multihazards (HM) and an increase in their number are noted after 2000. As a result of generalizing the information, a conclusion was made that a shift in the hydrometeorological regime of the Sea of Azov and the Caspian Sea reliably manifested itself in the early 2000s. It is shown that the hydrometeorological regime of the Sea of Azov is currently in a transitional state from one regime to another, while in the Northern Caspian the transition period has ended and further changes will be caused mainly by long-term fluctuations in sea level.