2011 Fiscal Year Final Research Report
Generation Mechanism, Structure and Dynamics of Violent Vortices in the Atmospheric Boundary layer and their Roles in Turbulent Transport
| Project/Area Number |
21340134
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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 | The University of Tokyo |
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Principal Investigator |
NIINO Hiroshi 東京大学, 大気海洋研究所, 教授 (90272525)
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| Co-Investigator(Renkei-kenkyūsha) |
IGA Keita 東京大学, 大気海洋研究所, 准教授 (60292059)
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| Project Period (FY) |
2009 – 2011
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| Keywords | 気象学 / 対流混合層 / 大気境界層 / ラージ・エディ・シミュレーション / 渦 / 塵旋風 / 竜巻 / 回転境界層 |
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| Research Abstract |
Generation mechanisms, structures and dynamics of dust devils, steam devils and tornadoes are studied. Dust devils are formed when circulation about the vertical axis, which is generated at mid-levels in a convective mixed layer, is transported by downdrafts toward low-levels, and then to updraft regions while nearly conserving the angular momentum. Steam devils in a moist convective mixed layer without precipitation develop in a similar way to dust devils. Those with precipitation, however, are caused by collisions of boundaries of cold pools from precipitating area. Radial distribution of tangential velocity in these strong vortices is found to have two different regimes which are dominated by the dynamics of a rotating boundary layer.
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