| Project/Area Number |
12125201
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Ocean Research Institute, The University of Tokyo |
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Principal Investigator |
NIINO Hiroshi Ocean Research Institute, University of Tokyo, Professor, 海洋研究所, 教授 (90272525)
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| Co-Investigator(Kenkyū-buntansha) |
KOMORI Satoru Kyoto University, Department of Mechanical Engineering, Professor, 大学院・工学研究科, 教授 (60127082)
MASUDA Akira Research Institute for Applied Mechanics, Kyushu University, Professor, 応用力学研究所, 教授 (60091401)
KIMURA Ryuji Ocean Research Institute, University of Tokyo, Professor Emeritus, 海洋研究所, 名誉教授 (20013576)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥68,700,000 (Direct Cost: ¥68,700,000)
Fiscal Year 2002: ¥34,800,000 (Direct Cost: ¥34,800,000)
Fiscal Year 2001: ¥33,900,000 (Direct Cost: ¥33,900,000)
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| Keywords | Environmental Turbulence / Tornadoes / Polar lows / Geostrophic turbulence / Rhines effects / Bathtub vortices / Surface renewal vortices / Exchange coefficient / スーパーセル / 二重拡散対流 / 地衝流乱流 / 中規模渦 / 地球温暖化 |
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| Research Abstract |
The structure and generation mechanism of large-scale elementary vortices such as tornadoes and polar lows in the atmosphere are clarified by high-resolution numerical simulations. A tornado spawned by a supercell storm is shown to develop along a gust front where verticity associated with the horizontal shear is concentrated and is further stretched by the storm updraft. Polar lows are shown to develop through baroclinic instability and latent heat release. When the baroclinicity is small a nearly axisymmetric vortex similar to a typhoon develops. When the baroclinicity is large, on the other hand, a meso-scale low accompanied with a comma-shaped cloud pattern develops. A laboratory experiment on a bathtub vortex show that the radial profile of the tangential velocity depends significantly on the characteristics of the botton boundary layer, which explains a wide variety of velocity distribution in atmospheric vortices
Also studied are statistical characteristics of turbulence under the effect of density stratification and earth's rotation with the beta-effect by a theoretical consideration and a numerical experiment. It is shown that the density stratification tends to suppress the Rhines effect to generate zonal mean flows. A self-similar solution for a decaying divergent rotating turbulence was found
Finally, turbulent transport processes of carbon dioxide through the air-sea interface are studied by laboratory and numerical experiments. It is found that the transport is dominated by large-scale elementary vortices called surface renewal vortices and the exchange coefficient is proportional to a square root of the generation frequency of the surface renewal vortices
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