| Project/Area Number |
15340154
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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 The University of Tokyo, Ocean Research Institute, Professor, 海洋研究所, 教授 (90272525)
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| Co-Investigator(Kenkyū-buntansha) |
IGA Keita The University of Tokyo, Ocean Research Institute, Associate Professor, 海洋研究所, 助教授 (60292059)
NAKAMURA Kozo Japan Agency for Marine-Earth Science and Technology, Frontier Research Center for Global Change, Researcher, 地球環境フロンティア研究センター, サブリーダー(研究職) (20143547)
SUZUKI Osamu Meteorological Research Institute, Meteorological Satellite and Observation System Department, Head of the second Research Laboratory, 気象衛星・観測システム研究部・第四研究室, 室長(研究職) (30354517)
石部 勝 気象研究所, 気象衛星・観測システム研究部, 研究官
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥16,300,000 (Direct Cost: ¥16,300,000)
Fiscal Year 2005: ¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 2004: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2003: ¥6,400,000 (Direct Cost: ¥6,400,000)
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| Keywords | cumulonimbus clouds / tornado / micorburst / downburst / supercell / mesocyclone / laboratory vortex / numerical simulation / ドップラーレーダー / シビアストーム / 環境パラメータ / 対流有効位置エネルギー |
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| Research Abstract |
A supercell storm and an associated major tornado were successfully reproduced in a semi-compressible non-hydrostatic meso-scale numerical model having a calculation domain of 66.4km × 66.4km × 15.1km, horizontal mesh size of 70m and 45 vertical levels. The storm was initiated by imposing a thermal bubble in a horizontally uniform environment that was adopted from the upper-air sounding on 20 May 1977 near Del City, Oklahoma in the United States. After 50 min from its initiation, a meso-low is formed at 2km above the ground level (AGL) as a result of the interaction between the storm updraft and the vertical shear of the horizontal flow. The upward pressure gradient accelerates the updraft below 2km AGL and produces a mesocyclone at 1.2km AGL by 60 min through tilting of horizontal vorticity and subsequent stretching. The rotation field lowers the pressure near the mesocyclone center, which further accelerates the updraft to reach 40m/s near 1km AGL. On the other hand, a gust front where rain-cooled air flowing out from a precipitating region and a warm moist environmental inflow meet is formed near the ground. The gust front is accompanied by vertical vorticity due to horizontal shear. When the strong updraft in the low-level mesocyclone comes right above the gust front, the vertical vorticity is stretched to form a tornado. A supercell tornado therefore is found to develop qualitatively in the similar way to a landspout which often develops along a meso-scale front where both convergence and horizontal shear are strong.
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