Characteristics of summer and winter circulations and their variability in the source area of the Tsushima Warm Current

On the basis of the hydrographical data obtained from the summer and winter cruises of 1990 investigated by China-Japan joint Research on the Kuroshio, combining with other cruises during the cooperation and partial historical data, the characteristics of the circulation and their variabilities in the study sea area are analysed in this paper.
It is pointed out that, in the Kuroshio eastward turning point, the sea water on its left side flows northward along the continental shelf edge and eastward or northeastward off the continental shelf edge in some degree then turns to northwest.Its bifurcated position is different, generally near the sea area 30°-31°N and 128°-129°E.The circulation between 30° and 31°N is unstable because of this.Since the eastward current appearing in the continental shelf edge between 30° and 31°N is common, the flowing path of the Tsushima Warm Current is usually in the type of "S".
It is also indicated that the Tsushiroa Warm Current mainly originates from the continental shelf water of the East China Sea in summer.and from the Kuroshio water in winter.