Does the subarctic circulation or Kuroshio-originating Warm Core Eddy have a stronger impact on winter sea surface temperature in the offshore region of the Sanriku coast, Japan?

Abstract

We used satellite data to investigate the impact of meso- to basin-scale physical oceanographic conditions on the interannual variations of winter (February to April) sea surface temperature (SST) in the offshore region of Sanriku coast, Japan during 1993–2021. Sea surface temperature in the region is influenced by the intrusion of cold water from the Oyashio and warm water from the warm core eddies (WCEs) originating from the Kuroshio Extension. We analyzed the relationships between SST and subarctic circulation intensity and between SST and the intensity of WCE activity. There was a strong correlation between SST and WCE activity intensity and no significant correlation between SST and subarctic circulation intensity. Our results suggest that strong WCE activity obstructs the southward intrusion of the cold Oyashio water into the offshore region of the Sanriku coast. As a result, the intensity of WCE activity influences interannual variations of winter SST in this region.