High interannual variability of summer surface salinity over the Laptev and East Siberian Sea shelves derived from historical records of the 1950s–2000s is attributed to atmospheric vorticity variations. In the cyclonic regime (positive vorticity) the eastward diversion of the Laptev Sea riverine water results in a negative salinity anomaly to the east of the Lena Delta and farther to the East Siberian Sea, and a positive anomaly to the north of the Lena Delta. Anticyclonic (negative) vorticity results in negative salinity anomalies northward from the Lena Delta due to freshwater advection toward the north, and a corresponding salinity increase eastward.

We study model climatic temperature and salinity fields and the fields of currents in the 350-1000-m layer. The following specific features are revealed: Colder waters are observed in the regions with anticyclonic vorticity. At the same time, warmer waters are detected in the regions with cyclonic vorticity. This temperature effect can be explained by the elevation of temperature with depth below the main pycnocline. In the region of the Sevastopol anticyclone, at depths greater than 500 m, we observe a zone of cyclonic rotation of waters. Near the Caucasian coast, in the region of Gelendzhik, we reveal a narrow jet current existing at a depth of 350 m from March till July.

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Modeling results of the Black Sea deep-water current reconstruction are considered. Computations are provided by applying the nonlinear z-coordinate model developed in Marine Hydrophysical Institute (MHI). Climatic atmospheric forcing and the atmospheric reanalysis data (ALADIN, Era-Interim) obtained for 2006, 2010 and 2013 are taken into account in different numerical experiments. The Black Sea climatology experiment is performed with a spatial grid step equal to 5 km, and in other experiments the 1.6 km grid step is used. Three-dimensional structure of the Black Sea currents on 45 levels within the surface horizon (2.5 m) and the bottom one (2100 m) is reconstructed. The anticyclonic current (countercurrent) extending along the Black Sea continental slope in direction opposite to the Rim Current is detected at about 1000 m and deeper. In the climatic fields the countercurrent exists in spring and summer in the northern part of the basin. In the experiments that included the reanalysis forcing, the countercurrent is revealed as separate streams in various continental slope areas and in different seasons. Its mean velocity is about 5 cm/s, the highest one is equal to 10 cm/s. In the overlying layer in the northeastern part of the Black Sea, the countercurrent is also detected by modeling as well as it is revealed by CTD and ADCP measurements.