the 22nd Pacific−Asian Marginal Seas meeting (PAMS)

The eastern Sakhalin shelf features an uplifted concentration of chlorophyll in autumn, due not only to the Amur River discharge but also to the specific multi-scale dynamics. The eastern Sakhalin shelf features the uplifted concentration of chlorophyll in autumn, due to the not only the Amur River discharge but the specified multi-scale dynamics. During the survey on the eastern Sakhalin shelf in autumn 2025, significant changes in thermohaline stratification were observed. The zonal section across the isobaths of the Sakhalin shelf showed that isopycnals abruptly deepened in the coastal zone, despite the East-Sakhalin Current intensifying during the season and the isopycnals having to elevate to the sea surface. The horizontal velocity from the ocean reanalysis showed that the East-Sakhalin Current can be unstable during wind of change events. Moreover, the eastern Sakhalin shelf was covered by the chain of the anticyclonic mesoscale eddies. Analysis of wind forcing during the expedition confirmed that a chain of mesoscale eddies formed when the wind direction changed from south to north. In addition, the comprehensive analysis of the isopycnal structure near the coast showed that northward winds drive coastal upwelling on the eastern Sakhalin shelf.  Thus, we observed manifestations of two phenomena associated with the anticyclonic mesoscale eddies and the coastal upwelling, which modified the isopycnal structure on the eastern Sakhalin shelf in autumn. These phenomena can be responsible for disrupting the strong density stratification induced by the Amur River discharge and for enhancing vertical fluxes between the sea surface and the bottom. This study was supported by the POI FEB RAS Program No. 124042300003-5.

coastal upwelling,mesoscale eddies,Sakhalin shelf