Observational study on the three-dimensional structure of a drainage flow
| Project/Area Number |
61540295
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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 | TOHOKU UNIVERSITY |
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Principal Investigator |
KAWAMURA Hiroshi (1987) Geophysical Institute, Tohoku University, 理学部, 助教授 (40169769)
萩野谷 成徳 (1986) 東北大, 理学部, 助手 (40150255)
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| Co-Investigator(Kenkyū-buntansha) |
HAGINOYA Shigenori Meteorological Research Institute, 物理気象研究所, 技官 (40150255)
安田 延寿 気象大学校, 助教授 (30004419)
佐藤 威 東北大学, 理学部, 助手 (30142920)
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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 |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Drainage flow / Parcel Model / Complex terrain / Energy exchange / Mountain and valley winds / V-shaped valley / 冷気層 / 山谷風 / 斜面流 |
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| Research Abstract |
(1) The "Parcel Model" of drainage flow was proposed by considering its momentum and sensible heat transports. The thickness h and velocity u of the Parcel, corresponding to the inversion height and maximum velocity of actual drainage fow, respectively, were derived in terms of the following parameters: the length and vertical drop of the slope, potential temperature difference between the ambient atmosphere and the Parcel, aerodynamic condition of the slope surface expressed by the mean bulk coefficients, and ambient stability. The mean bulk coefficients depend not only on the roughness lengths (z_o and z_<<theta>>) but also on the slope length. The predicted thickness and velocity of drainage flow agree with the observations on slopes several tens of meters to several hundred kilometers long.
(2) Three-dimensional distributions of wind speed and temperature in a V-shaped valley were continuously observed. Analyzed typical drainage flows (79 cases) show the following features: The cold layer in the valley consists of two parts (drifted cold layer and primary cold layer); temperature gradient is constant in the drifted cold layer; wind profile of drainage flow is parabolic; maximum velocity is proportional to a square root of cooling strength and the thickness slightly increases with cooling strength. Horizontal heat fluxes due to drainage flow were estimated at two separate cross sections, leading to the values of C_H and B_H^<-1> to be 0.01 and 20, respectively.
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Report
(2 results)
Research Products
(8 results)
