TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 49 (No. 6), pp. 667-682, 1993

The Kyuchoin Sukumo Bay Induced by Kuroshio Warm Filament Intrusion

Hideki Akiyama1 and Sei-ichi Saitoh2

1Department of Civil and Ocean Engineering, Ehime University, Bunkyo 3, Matsuyama 790, Japan
2Meteorological Information Center, Japan Weather Association, 4-5, Koji-machi, Chiyoda-ku, Tokyo 102, Japan

(Received 24 November 1992; in revised form 4 March 1993; accepted 7 June 1993)

Abstract: Surface temperature data obtained in and out of the bay all year round from March 1990 through February 1991, except from July through October 1990 were analyzed to investigate seasonal variability of the Kyuchoin Sukumo Bay, southwest of Shikoku, Japan. The Kyuchoperiodically occurs in the bay during both the warming period of March through June and the cooling period of November through February. The onset period of the Kyuchois 8-15 days during the warming period and 4-14 days during the cooling period, giving an average of about 10 and 8 days, respectively. The position of the Kuroshio axis offshore in the south of Cape Ashizuri-misaki is a significant factor with the Kyuchoin the bay. Thermal infrared images taken by the NOAA-11 in the sea off east of Kyushu were also analyzed during the two observation periods. It is clearly found that a warm filament derived from the Kuroshio (KWF) advects northeast to Cape Ashizuri-misaki along the Kuroshio, then encounters the southwest coast of Shikoku, followed by inducing the Kyuchoin the bay by the warm water intrusion. The alongshelf dimension of the KWFs is approximately 50-100 km, and the cross-shelf distance from the western edge of the KWFs to that of the body of the Kuroshio is about 30-50 km. The KWF sometimes closely approaches to the east coast of Kyushu. An onshore meander of the Kuroshio front around Cape Toi-misaki might grow into a KWF in the sea off east of Kyushu.

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