Co-Investigator(Kenkyū-buntansha) |
RIKIISHI Kunio Hirosaki U., Faculty of Sci. & Eng., Professor, 理工学部, 教授 (70038561)
OTOBE Hirotaka Ocean Research Institute, Research Associate, 海洋研究所, 助手 (10169328)
YANAGIMTO Daigo Ocean Research Institute, Research Associate, 海洋研究所, 助手 (40260517)
KOGA Momoki Ryukyu U., Faculty of Science, Associate Professor, 理学部, 助教授 (50153515)
HASHIMOTO Yoshio Kyushu U., Research Institute of Applied Mechanics, Associate Professor, 応用力学研究所, 助教授 (80180842)
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Research Abstract |
We have carried out oceanographic studies on scientific methodology of two types of newly developed observation methods, with a particular focus upon effective monitoring system for oceanic currents both in the East China Sea and the Sea of Japan that complement the existing observation network there. One of the methods is PALACE (Profiling Autonomous Lagrangian Circulation Explorer). Tracks of two of four PALACE floats deployed in the Sea of Japan, and temperature profiles measured with these floats were analyzed. They showed, for example, a subsurface circulation at the depth of 400-500db, even in the northern part of the Sea of Japan where it is not practically easy to often collect in situ oceanographic data by ordinary methods. The other is usage of submarine cables to monitor the volume transport of oceanic currents flowing above the cables. It was demonstrated that volume transport was proportional to electromotive force induced by the current over the cable at all study sites, including Tsugaru St.. Tsushima St.. Tokara St., the region of Izu Islands and southwest of Okinawa. The relationship between two values was presented for each study site. And by using the relations, mean volume transport of the Kuroshio at Izu region, transport variability through Tokara St., and that through Tsushima St. were estimated at 48Sv, 6Sv and 2Sv. respectively. It was also pointed out that the transport through Tsushima St. showed a short-term fluctuation with approximately daily time scale responding to the changes of wind over the Strait while fluctuations with a time scale of a week to ten days were dominant in Tokara St, and the region of Izu Islands. Both methods studied in the present study were workable to monitor oceanic currents, particularly from a view point of establishment of hybrid observing system with existing networks.
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