Features of the Structure and Dynamics of Waters in the Northern Half of the Sea of Japan in the Autumn–Winter Period According to Satellite and Ship Observations

Abstract—This article presents the results of studies of the structure and dynamics of waters in the large-scale cyclonic gyre (LSCG) zone in the northern half of the Sea of Japan, where two areas of low temperatures separated by the influx of warm Tsushima waters from Japan are most clearly visible on satellite IR images every autumn–winter period. The location of these thermal structures coincides with the location of the small western and northern cyclonic gyres, which are inextricably linked with deep upwelling. In the autumn–winter periods of 2019–2021, it was established that deep upwelling in the northwestern part of the Sea of Japan extends from the bottom to the surface layer, focusing along the axial line passing through the Pervenets Rise and the Bersenev and Vasilkovsky ridges in the region of 42° N between 132° E and 135.5° E. The cyclonic gyre (WCG) located in the western part of the LSCG in the area of deep upwelling under consideration is a large topographic eddy. In the northern part of the LSCG, the deep upwelling is confined to the continental clone, where the northern cyclonic gyre (NCG) is also located. It is assumed that in the autumn–winter period, the interaction of anticyclones that form vortex belts with cyclonic gyres leads to an increase in deep circulation. The peculiarity of the variability of the velocity of deep currents—an increase from October to March—is probably due to the developmental nature of vertical and transverse horizontal circulation in the system of cyclonic gyre–vortex belt system as a result of the intensification of deep upwelling with the strengthening winds from northern directions in winter.