Variability of Summer Wind-Driven Upwelling along the Koryak Coast in the Northwestern Bering Sea Based on Satellite Data

The variability of upwelling along the Koryak coast in the northwestern Bering Sea is studied using wind data from the QuikSCAT/SeaWinds (2000-2009) and MetOp-A/ASCAT (2010-2020) scatterometers. The strength of upwelling is estimated based on the wind speed and wind-induced offshore Ekman mass transport (upwelling index). The results indicate that the upwelling that occurred along the Koryak coast was primarily driven by the southerly summer winds over the Bering Sea. The Koryak coastal upwelling occurs mainly during June-August, with significant interannual variability. The variability of the upwelling is primarily driven by regional wind forcing. The seasonal variability of southerly winds favorable for the development of upwelling largely depends on the state of the summer Far Eastern depression (a regional atmospheric center of low pressure). The variations in the pressure field correlate well with the successive alternation of upwelling and downwelling processes near the Koryak coast. Intense upwelling is associated with the well-developed Far Eastern depression. Upwelling can be replaced by downwelling when this regional center of atmospheric action is weakened.