Some problems of circulation and hydrography of the japan sea and the tsushima current

Abstract

The Tsushima Current is formed through the lateral flow of the Kuroshio due to horizontal Reynolds stresses or by the bottom topography which causes northward movement of a part of the Kuroshio transport as shown by a numerical model. The northward transportby the wind stress in the Korean Strait superposes on either of these two transports. The annual change of the Tsushima Current transport determined either from the Reynolds stresses by use of GEK data or by the geostrophic flow of the numerical model in addition to the wind stress transport agrees with that determined by the geostrophic method. The sea level difference between 30°N and 42°N which was believed as the primary cause of the Tsushima Current is determined from the wind curl over the north Pacific Ocean.It is large in winter and small in summer and opposite in phase to the annual change in the dynamic depth anomaly difference between the East China Sea and the Tsugaru Strait, due to the difference in response of the barotropic and baroclinic mode to the time-varying wind stresses. The Japan Sea shows features of a mini-ocean in circulation and hydrography.A branch of the Tsushima Current in the Japan Sea flows off the Korean coast and turns eastward as the western boundary current separates from the coast because of the southward Ekman transport in the upper layer of a two-layer ocean.The main branch flowing along the Japanese coast turns eastward following the isobaths because of conservation of the potential vorticity in a barotropic sea with topography near an inlet.The change of the maximum salinity in the Tsushima Current can be explained by the advection diffusion equation of salinity. The double oxygen maxima in the same region are caused by southwardflow of the deep water and northward flow of the Tsushima Current water.The former is generated by the meridonally increasing density at the surface and the wind stress in the northern half of the Japan Sea and produces almost uniform water below 400m. © 1984, Elsevier Inc. All rights reserved.