TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 49 (No. 4), pp. 369-382, 1993

The Kyucho in the Bungo Channel, Japan—Periodic intrusion of oceanic warm water

Hidetaka Takeoka1, Hideki Akiyama1 and Takahiro Kikuchi2

1Department of Civil and Ocean Engineering, Faculty of Engineering, Ehime University, Bunkyo 3, Matsuyama 790, Japan
2Ehime Chuyo Prefectural Fisheries Experimental Station, Mori, Iyo 799-31, Japan

(Received 11 April 1992; accepted 21 October 1992)

Abstract: "Kyucho" is a sudden and swift current which is usually accompanied by rise of water temperature. Several features of the Kyucho in the Bungo Channel, Japan, are presented through field observations. The Kyucho in the Bungo Channel is an intrusion of warm water from the Pacific Ocean into the eastern half of the Bungo Channel, being driven gravitationally and advancing along the eastern coast of the channel. The Kyucho occurs usually in summer and seldom occurs in winter. It occurs at neap tides showing the prominent spring-neap periodicity. The modulation of the vertical mixing intensity associated with the variations of tidal current, wind and surface heating etc. is supposed to be a main cause of spring-neap and seasonal periodicities.

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