1999 Fiscal Year Final Research Report Summary
The Effect of Double Diffusive Convention in the Mixing region at the oceanic front
| Project/Area Number |
10640419
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Tokyo University of Fisheries |
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Principal Investigator |
YOSHIDA Jiro Tokyo University of Fisheries, Department of Ocean Sciences, Associate Professor, 水産学部, 助教授 (30174931)
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| Co-Investigator(Kenkyū-buntansha) |
NAGASHIMA Hideki Tokyo University of Fisheries, Department of Ocean Sciences, Professor, 水産学部, 教授 (10087570)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Oyashio Front / Temperature inversion / Double diffusive convection / Neutral surface / cabbeling / Salt finger / thermobaric effect / Kelvin-Helmholtz instability |
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| Research Abstract |
1. Detailed CTD, XCTD and ADCP data at the Oyashio Frontal region were analyzed.
(1)Temperature inversion layers were frequently observed as the Oyashio Water mass extended from north. Hot/salty and cold/fresh water masses were piled up alternatively in the vertical direction suggesting the active double diffusive convection.
(2)Temperature inversion layers were observed more at the offshore region than the coastal region. And the strong temperature inversions were observed more at the northern area where the Oyashio and the Kuroshio waters were contacted directly.
(3) Neutral surface analysis was applied for the Oyashio region to the Kuroshio Extension, which reveals the important role of cabbeling and salt finger convection to the modification process of the Northa Pacific Intermediate Water (NPIW).
2. To understand the deep convection process at the polar region, thermobaric effect on the onset of deep convection was conducted.
(1) With the introduction of thermobaric effect, deep convective plumes were occurred even when the fluid layer was stably stratified.
(2) As for the case when the double diffusive effect is introduced to the above case, the onset of convection was suppressed by the double diffusion.
3. Double diffusive lock exchange flow is investigated numerically, and as a result, Kelvin-Helmholtz instability usually appeared at the interface was suppressed by the introduction of double diffusive convection.
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