| Project/Area Number |
23540516
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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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 |
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| Co-Investigator(Kenkyū-buntansha) |
NISHINA Ayako 鹿児島大学, 水産学部, 助教 (80311885)
YAMASHIERO Toru 鹿児島大学, 理工学研究科, 教授 (20158174)
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| Project Period (FY) |
2011 – 2013
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| Project Status |
Completed (Fiscal Year 2013)
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| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2013: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2012: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Fiscal Year 2011: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | 沖縄トラフ / ケラマギャップ / 北太平洋中層水 / 琉球海流系 / ハイドロリック・コントロール / 鉛直拡散係数 / 湧昇流 / 深層循環 / 国際研究者交流 / 韓国 / overflow / 鉛直混合 / 琉球海流 / 国際情報交換 / アメリカ合衆国 / 海洋物理学 / hydraulic control / 海洋観測 |
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| Research Abstract |
Circulation and water mass formation in the intermediate and deep layers of the Okinawa Trough were investigated using comprehensive datasets for 1) water properties on the minimum salinity surface mainly derived from Argo float profiles, 2) velocity data in the Kerama Gap measured by moored current-meters from 2009 to 2011, and 3) CTD/LADCP data over the southern Okinawa Trough measured in Junes 2011 and 2013.
Intermediate-water properties are largely modified in the Okinawa Trough due to strong diapycnal diffusion (6.8-21.5 cm2/s based on an advection-diffusion equation). Deep water below the sill depth of the Kerama Gap (~1100 m), is ventilated by the bottom-overflow in the Kerama Gap down to the deepest layer (~2000 m) in the southern Okinawa Trough. A box model predicts that this bottom-overflow (0.18-0.35 Sv) causes strong upwelling in the southern Okinawa Trough, which must be maintained by buoyancy gain of the deep water due to strong diapycnal diffusion (4.8-9.5 cm2/s).
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