| Project/Area Number |
61460047
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 | University of Tokyo |
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Principal Investigator |
KIMURA Ryuji Associate Professor, 海洋研究所・海洋気象部門, 助教授 (20013576)
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| Co-Investigator(Kenkyū-buntansha) |
NIINO Hiroshi Meteorological Res. Inst., 物理気象部, 研究官 (90272525)
NAKAMURA Kozo Reseach Associate,Univ. of Tokyo, 海洋研究所・海洋気象部門, 助手 (20143547)
ASAI Tomio Professor,UNiv. of Tokyo (BABA,Hiroshi), 海洋研究所・海洋気象部門, 教授 (80025288)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1987: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1986: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | monsoon / cold air-mass / shiberian high / northwest seasonal wind / 温帯低気圧 |
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| Research Abstract |
Monsoon is the atmospheric circulation driven by temperature difference between lands and oceans. The dynamics is controlled by 1)density stratification of the atmosphere, 2)differential heating at the lower boundary, 3)diffusion proces of heat and momentum, 4)Coriolis force and 5)seasonal variation of the temperature contrast between lands and oceans. In this study hydrodynamic characteristics of the atmosphere subject to these factors have been investigated by a linear theory and a laboratory experiment. The objective of the linear theory is to determine the horizontal scale of the circulation produced by differential heating. It was found that the horizontal scale is given by N K^<1/2>w^<-3/2>F(f/w), where N is the buoyancy frequency, K is the diffusion coefficient, w is the angular frequency of the thermal forcing and f is the Coriolis parameter. In the laboratory experiment we investigated effects of the rotation to the flow pattern: When the rotation rate is small, the circulation is axisymmetrical without any frontgenesis. When the rotation rate exceeds a critical value, it turns out to be wavy due to barolinic instability. Formation of the cold front takes place in the unstable situation. The behaviour showed remarkable similarity to that of the actual cold front observed in the atmospehre.
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