A sudden switch from upwelling to downwelling along the Southeastern coast of Korea due to the passage of two typhoons

초록

Typhoon-induced strong winds can dramatically change the oceanic environments, which sometimes can damage the fishery industry and nuclear power plant located along the coast. Coastal upwellings and downwellings due to continuing strong winds along the coast create sudden water property changes near the Korean coast. In July 2015, two consecutive typhoons, Chan-hom and Nangka, passed through the Yellow and East Seas. These typhoons formed a switching event of strong southerly and northerly winds within a week along the southeastern coast of Korea. Current profiles and near-bottom temperature measured by a bottom-mounted acoustic Doppler current profiler (ADCP) near Gijang (lat?, lon?) show sequential upwelling and downwelling events corresponding to the wind changes. During this event, internal tides vary differently from the barotropic tidal forcings. The analysis of the ocean forecast system output shows that the propagation of internal tides were modified by the abrupt changes of stratification induced by the consecutive upwelling and downwelling event. This result presents a case study showing that typhoon?induced stratification changes can affect propagation of internal tides which charges a large part of the ocean mixing process. Our study implies that the predicted changes of typhoon intensity and passage associated with the climate change would significantly affect the oceanic environment along the coastal regions where the human activity and natural variability are vigorous.