Seasonal Variations and Long-term Trends of the Coastal Upwelling along the Southwestern Coast of the East Sea/Japan Sea

Abstract

Southwesterly winds cause coastal upwelling along the southwestern coast of the East Sea/Japan Sea (EJS) in summer. To investigate the seasonal variations and long-term trends in the coastal upwelling, the observations of the Sea Surface Temperature (SST) at Gampo and the wind at Busan from 1968 to 2012 were analyzed. Upwelling signals estimated by temperature anomalies were negatively correlated (r approximate to -0.6) with southwesterly winds in summer. In addition, the signals were closely related to the Net Primary Production (NPP) near the upwelling region in late spring to early summer, which was the reason for the summer NPP peak in this area. The upwelling index driven by the wind shows that the upwelling would occur from April to August with a maximum strength in July. The long-term upwelling trends differed considerably according to the season: they increased in spring and decreased in summer, but the interannual variability in summer reduced the statistical confidence of the trends.