1992 Fiscal Year Final Research Report Summary
Axis, velocity and volume transport of the Kuroshio in the Tokara Strait
| Project/Area Number |
02640319
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
気象・海洋・陸水学
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| Research Institution | Kagoshima University |
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Principal Investigator |
MAEDA Akio Kagoshima University, Ocean Civil Engineering, Professor, 工学部, 教授 (90013573)
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| Co-Investigator(Kenkyū-buntansha) |
YAMASHIRO Toru Kagoshima University, Ocean Civil Engineering, Research Associate, 工学部, 助手 (20158174)
SAKURAI Masahito Kagoshima University, Ocean Civil Engineering, Assistant Professor, 工学部, 講師 (10094145)
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| Project Period (FY) |
1990 – 1992
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| Keywords | North pacific climate system / Volume transport of the Kuroshio / Tokara Strait / Migration of the Kuroshio front / Sea level records / Satellite infrared image / A typical temperature showing the axis of the Kuroshio / Averaged position of the axis of the Kuroshio |
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| Research Abstract |
It is necessary for understanding North Pacific climate system to monitor volume and heat transports of the Kuroshio. The Tokara Strait is a convenient sea area for monitoring of the transports. Many phenomena which have different time and space scales contribute fluctuation of the volume transport estimated from fluctuation of a sea level slope. For an example, migration of the Kuroshio front in the strait will contribute the fluctuation. So, we described relations between the front migration and the transport fluctuation, vertical structure of the front and generation of the front migration, using satellite infrared image, sea level records and time series of sea surface temperature. From the analyses, we got following results. 1. Northward migration of the front which extends from the sea surface to about 200m deep and originates from tongues of the shelf water west of the Yakushima is accompanied by increase of the volume transport between the Nakanoshima and the Satamisaki. 2. The inflow into the Kagoshima bay and the Ohsumi Branch Current strengthen after about 4 days of the northward migration.
Although the front has been generally found between the Nakanoshima and the Yakushima, a major part of the volume transport of the Kuroshio is supposed to exist south of the Nakanoshima. This means that the axis of the Kuroshio will exist south of the island. So, we determined average position of the axis analyzing data of BT and GEK and measured subsurface velocity at a cite south of the Nakanoshima where the water depth is 750m. From the analysis and the measurement, we got following results. 3. A typical temperature showing the axis is 17.2ﾟC at 200m depth. The averaged position of the axis is near the Nakanoshima. The standard deviation of the position is *25km. 4. Velocity at 500 depth is higher than that at 300m deep and approximately parallel to isobaths.
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