TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 54 (No. 1), pp. 101-114, 1998

The Behavior and the Role of the Anti-Cyclonic Eddy in the Kuroshio Large Meander Development

Futoki Sakaida1, Daisuke Egusa2 and Hiroshi Kawamura3

1Ocean Mechanical Engineering Chair, Kobe University of Mercantile Marine, 5-1-1, Fukae Minami machi, Kobe 658, Japan
2ZUKEN Inc., 2-25-1, Edahigashi, Yokohama 224 Japan
3Center for Atmospheric and Oceanic Studies, Faculty of Science, Tohoku University, Aoba, Sendai 980-77, Japan

(Received 10 February 1997; in revised form 3 October 1997; accepted 16 October 1997)

Abstract: The processes underlying the development of the Kuroshio large meanders that occurred in 1986 and 1989 are investigated using a satellite SST data set and hydrographic data. In both processes visible on the satellite SST images, a round-shaped, lower SST region with a diameter of about 200 km is found to the east of the Kuroshio small "trigger" meander (Solomon, 1978) until the region became extinguished near the Enshu Nada. The lower SST region can be interpreted as an anti cyclonic eddy, mainly because of the existence of a warm water mass in the subsurface layer of this region. The warm water mass is characterized by a constant temperature of 18-19°C, the maximum thickness of which is about 400 m. The satellite images show that the eddy is closely related to the Kuroshio path transforming into a shape like the letter "S". This means that the eddy plays an important role in the development of the Kuroshio large meander since this, too, tends to follow an "S"-shaped path. Added to this, the subsurface layer structure of the eddy is similar to that of the warm water mass off Shikoku. This similarity, together with the eddy behavior visible on the satellite SST images, implies that the examined eddy corresponds to the warm water mass off Shikoku. In other words, the warm water mass off Shikoku can be advected near to the Enshu Nada when the Kuroshio large meander occurs.

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