| Project/Area Number |
16340142
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Kagoshima University |
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Principal Investigator |
NAKAMURA Hirohiko (2005-2006) Kagoshima University, Faculty of Fisheries, Associate Professor, 水産学部, 助教授 (50284914)
市川 洋 (2004) 鹿児島大学, 水産学部, 教授 (60128410)
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| Co-Investigator(Kenkyū-buntansha) |
NISHINA Ayako Kagoshima University, Faculty of Fisheries, Research Associate, 水産学部, 助手 (80311885)
中村 啓彦 鹿児島大学, 水産学部, 講師 (50284914)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥11,200,000 (Direct Cost: ¥11,200,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2005: ¥4,700,000 (Direct Cost: ¥4,700,000)
Fiscal Year 2004: ¥4,500,000 (Direct Cost: ¥4,500,000)
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| Keywords | Kuroshio / Continental slope / Deep countercurrent / East China Sea / Oceanic observation / Current / Moored current meter / self-organization / 陸棚斜面 |
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| Research Abstract |
Previous observations have indicated that the deep countercurrent is present beneath the Kuroshio on the continental slope in the East China Sea. However, its persistency and spatial extent along the continental slope have not been clarified as yet. We carried out 2-years moored current meter measurements at four locations in the slope area near 27-29° N, and observed ten snapshots of velocity and hydrographic sections containing the deep countercurrent for the period November 2004 and November 2006. The deep countercurrents were clearly identified to the velocity records in which high-frequency fluctuations (periods shorter than about 20 days) due to Kuroshio front meanders were removed. Structures of the deep countercurrent had differences between the central and northern slope areas, the boundary of which corresponded to the climatological mean position where the Kuroshio separates from the continental slope. The location of the deep countercurrent was deeper in the central slope area than in the northern one. The deep countercurrent had a clear season-fixed nature especially in the central slope area, i.e., periodic countercurrents that vary with periods of 1-2 months were organized into a persistent countercurrent in winter-spring seasons, and in this time the Kuroshio front meanders with periods shorter than 20 days tended to diminish. Mechanisms that form the persistent deep countercurrents in the central and northern slope areas are discussed in relation to the inverse energy cascade and the Kuroshio separation fro n the continental slope, respectively.
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