A SUMMERTIME SUBSURFACE COUNTERCURRENT IN THE EAST COAST OF JEJU-DO

Abstract

Understanding the current system is essential to study oceanic environment problem. In order to monitor the current structure near Jeju-do in the northern East China Sea where the water depth is about 70 m and the Thushima Current passes, Korea Institute of Ocean Science and Technology deployed a current meter (Aquadorpp 400kHz Profiler) mooring in the region southeast of Jeju-do in May 2012. The time series current data recorded in the site reveal the strong seasonal variation of current structure. The wintertime current was dominated by the northeastward Thushima Current and showed the barotropic vertical structure. In summer, however, an unexpected subsurface (southward) countercurrent was observed in the depth below the pycnocline with its maximum speed of about 50 cm/sec. It is also found that the existence of southward coastal undercurrent is consistent with the appearance of bottom cold water observed in the region in summer.orea Institute of Ocean Science and Technology deployed a current meter (Aquadorpp 400kHz Profiler) mooring in the region southeast of Jeju-do in May 2012. The time series current data recorded in the site reveal the strong seasonal variation of current structure. The wintertime current was dominated by the northeastward Thushima Current and showed the barotropic vertical structure. In summer, however, an unexpected subsurface (southward) countercurrent was observed in the depth below the pycnocline with its maximum speed of about 50 cm/sec. It is also found that the existence of southward coastal undercurrent is consistent with the appearance of bottom cold water observed in the region in summer.