TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 52 (No. 4), pp. 491-507, 1996

Process of the Tsushima Current Formation Revealed by ADCP Measurements in Summer

Osamu Katoh1, Kazuyuki Teshima1, Osamu Abe1, Hitoshi Fujita1, Kuniaki Miyaji2, Kenji Morinaga1 and Norihisa Nakagawa1

1Seikai National Fisheries Research Institute, 49 Kokubu-machi, Nagasaki 850, Japan
2National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa-ku, Yokohama 236, Japan

(Received 24 October 1995; in revised form 11 January 1996; accepted 23 January 1996)

Abstract: In order to clarify detailed current structures over the continental shelf margin in the East China Sea, ADCP measurements were carried out in summers in 1991 and 1994 by the quadrireciprocal method (Katoh, 1988) for removing diurnal and semidiurnal tidal flows from observed flows, together with CTD measurements. We discussed the process of the Tsushima Current formation in the East China Sea. The Tsushima Current with a volume transport of 2 Sv (1 SV = 106 m3s-1) was found north of 3°N. A current with a volume transport of 0.4 Sv was clearly found along the 100 m isobath. Between the Kuroshio and the current along the 100 m isobath, southeastward component of velocity was dominant compared to northwestward one. Four eastward to southeastward currents were found over the sea bed shallower than 90 m depth. Total volume transport of these four currents was 1 Sv, and they seemed to be originated from the Taiwan Strait. Intrusion of offshore water into the inner shelf northwest of Amami Oshima was estimated to have a volume transport of 0.6 Sv. It is concluded that the Tsushima Current is the confluence of these currents over the continental shelf margin with the offshore water intruding northwest of Amami Oshima.

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