Circulation and Mesoscale Eddies in the Sea of Japan from Satellite Altimetry Data

Abstract

The spatial distribution and seasonal variability of mesoscale eddies in the Sea of Japan were investigated based on the regional database created from the AVISO Atlas of Mesoscale Eddies (1993–2020). The database contains information about the trajectories and parameters of mesoscale eddies in the ocean. The eddies detection method is based on the analysis of altimetric maps of absolute dynamic topography. A total of 578 eddies with a with a lifetime of more than 90 days were identified (273 anticyclonic and 305 cyclonic). The average lifetime for the Sea of Japan regional data set of eddies is 202 days for anticyclonic and 143 days for cyclonic and mean radius of 59 ± 11 km for anticyclonic and и 61.0 ± 12 km for cyclonic. The mean speed of anticyclones and cyclones along their trajectories was 2.8 and 3.7 cm/s, the average orbital velocities of geostrophic currents were 19.0 and 15.1 cm/s, respectively. The maximum number of cases of formation and destruction of anticyclones falls in July–September during the period with high values of water inflow through the Korea Strait. Most of the cyclonic eddies are generated between January and June and decay the cold half of the year (October–March). Тhe joint analysis of maps of the mean surface circulation in the Sea of Japan (satellite altimetry data) and the spatial distribution of mesoscale eddy showed that the stable eddies of the Sea of Japan are associated with the quasi-stationary meanders of the of the East Korea current, Subpolar Front, and Tsushima current. The position of meanders is mainly determined by the interaction of the currents with the bottom topography.