Dynamic structure of the Oyashio, 1: Net geostrophic transport balance and flow path of the Oyashio water during summer in 1989
1991
Kawasaki, Y. (Hokkaido National Fisheries Research Inst., Yoichi (Japan)) | Kono, T. | Kashiwai, M. | Okuda, K.
Volume transport of the Oyashio and its net transport balance are calculated from the CTD observations around south of Kuril Islands, southeast of Hokkaido and east of Tohoku sea area during summer 1989. Transport balance, calculated from closely and equally spaced CTD data which are distributed in ca. 150 triangles with 42 km side length are shown a synoptic circulation pattern over a 140,000 km2 sea area adjacent to Japan. The coastal Oyashio Current, Oyashio 1st Branch (Oy1) consists of two flow path, first, the flow over continental shelf, originated in the Sean of Okhotsk, passing through the Proliv Bussol with a transport of 3 x 10(6) m3s(-1) (Sv) and second, the flow with a circuitous route round WCR-86B off Shikotan Island, originated in south of Ostrov Simshir with a transport of 4-6Sv. These flows are characterized as a one-way directed flow toward southwest and south, and its water characteristics on 120cl/ton surface are not modified during its southward movement. Some cyclonic eddies are observed between Oyl and warm-core ring (WCR) off Kushiro. One of which located of Hachinohe shows an obvious deep cyclonic circulation over 4Sv. Cyclonic eddies, their water characteristics are different from Oyl or WCR, seem to play a major role in modifying Oyashio Water. The synoptic observed Oyashio's dynamic structure, consists of one-way directed flow with deep cyclonic eddies, shows a marked difference from the previous study, the Oyashio intrusion with a return flow
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