Seasonality of Heat Exchange on the Barents Sea Surface

Over the past 40 years, the Arctic, and the Barents Sea in particular, has undergone considerable changes in the state of the atmosphere, sea ice, and water column, which are presumably beginning start to affect the duration of the warm period (when the sea uptakes heat from the atmosphere) and the cold period of the year (when the sea loses heat to the atmosphere). This study considers the interannual variability of the onset dates and duration of the warm and the cold periods of the year. Data on short- and long-wave radiation, as well as on sensible and latent atmospheric heat fluxes from the ERA5 reanalysis were used. HDBSCAN cluster analysis method has made it possible to identify four regions (clusters) with synchronous dynamics of the dates of transition of the heat balance through zero. Several delineated regions are located on the pathway of the Atlantic origin water in the Barents Sea. A vast region has been distinguished in the northern part of the sea, where the inflow of the cold Arctic water occurs, providing cooling and freshening of Atlantic water transported from the Norwegian Sea. A shift in the date of heating onset in the southern and southeastern parts to later dates (4-5 days per 10 years) and a shift to earlier dates in the northern and northeastern parts of the sea (4-5 days per 10 years) have been detected. For heating termination dates, the opposite situation shift compared to the heating onset dates is observed. In the southern part, there has been a shift to earlier dates (1-2 days per 10 years), and in the northern part, to later dates (4-5 days per 10 years).