The energetic surface circulation patterns of the Japan/East Sea

Abstract

Abstract In the period of 1988–2001, 226 ARGOS fixed drifters were deployed in the Japan/East Sea (JES). From these and the historical file of temperature at a depth of 100 m, 15 m depth circulation and its variances in relationship to the seasonal mean warm and cold water regions were constructed on 0.5° resolutions. The strongest seasonal currents were: the East Korean Warm Current (EKWC), the Tsushima Current (TC), the North Korean Cold Current (NKCC) and local eastwards intensifications along the sub-polar frontal patterns. The TC and NKCC were observed during summer and drifters passed through the Soya Strait only in summer. The sub-polar front occurred along 40°N in the northeastern JES; a separate front occurred in winter that was associated with the flow of warm water restricted to the southern JES. Small eddy energy was found in the cold water regime and large eddy energy in the warm water regime. Satellite altimeter and drifter tracks were used to mark the Wonsan Eddy found in the East Korean Bay, a yearly late summer occurrence. Mechanical energy flux from the mean circulation to mesoscale eddies occurred in EKWC, TC and the sub-polar front in the eastern JES with eddy kinetic energy doubling time of 15–60 days. The yearly mean circulation east of the Korean coast is organized into a broad, eddy-filled East Sea Current that contains weak anticyclonic gyres in the Ulleung and Yamato Basins. It accelerates toward the Yamato Rise and against the eastern coast of the JES. The published numerical model solutions show several historical circulation features but fail to capture many of the new structures described by the drifter data.