Water dynamics in the western Bering Sea and its impact on chlorophyll a concentration

To study the water dynamics in the western Bering Sea, the time series of geostrophic velocities derived from satellite altimetry, Global total current (Copernicus Globcurrent) velocities, Argo buoys, and ship, borne data are analyzed. We demonstrate that the surface currents in the study area are characterized by a significant seasonal and interannual variability. In January, the southwestern currents are prevailing in the western Bering Sea, the geostrophic currents are connected to the continental slope, and mesoscale anticyclonic movement of waters is observed on the shelf. In July, the surface flow is oriented to the northeast along the continental slope, and cyclonic water movement prevails on the shelf. The formation of mesoscale anticyclones in late winter - early spring - is related to the supply of low-temperature and low-salinity Bering Sea shelf water. The temporal variability of the direction and current velocity in the western part of the Bering Sea during the summer period is associated with the wind and coastal upwelling. The presence of coastal upwelling and eddies should be considered as one of the factors leading to the high concentration of chlorophyll a on a shelf and continental slope in the summer.