Ivanov V.V., Golovin P.N.

Temperature and salinity variability in the upper 20-meter ocean layer in the 1950–2014 time interval were analyzed on the basis of the observational data. Four typical regions were selected for this study in the central part of the Arctic basin and two regions on its border with the Laptev Sea. The analysis allowed revealing that until the 1990s, when most of the Arctic basin was covered with perennial ice all year round, the temporal variability of the thermohaline parameters in the upper mixed layer in all the considered areas was small throughout the year. Since mid‐1990s, multidirectional changes in the thermohaline parameters in the upper layer have been observed in the western and eastern parts of the Arctic basin. In the Western region in the winter season, salinization and cooling of surface waters are happening, whereas in the eastern Arctic, on the contrary, there is strong desalination and a corresponding increase of water temperature. One of the main reasons for the desalination of surface waters in the eastern Arctic is a reduction in the area of perennial ice and its replacement by seasonal one against the background of increased riverine water discharge and change in the atmospheric circulation over the Arctic. The salinization of surface waters in the western Arctic is associated with an increase in the supply of saline Atlantic waters from the Fram Strait and their rise to the surface under conditions of increased seasonality of Arctic sea ice, which refers to an increase in the duration of the melting season.

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