1987 Fiscal Year Final Research Report Summary
Energy transport in the atmospheric boundary layer over the complex ground surface
| Project/Area Number |
61460046
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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 | TOHOKU UNIVERSITY |
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Principal Investigator |
KONDO Junsei Geophysical Institute, Tohoku University, 理学部, 教授 (30004493)
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| Co-Investigator(Kenkyū-buntansha) |
KUWAGATA Tsuneo Geophysical Institute, Tohoku University, 理学部, 助手 (90195602)
SATA Takeshi Geophysical Institute, Tohoku University, 理学部, 助手 (30142920)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Bulk heat transfer coefficient / Canopy flow / Drainage flow / Aerodynamic roughness length / 積雪面粗度 / 抵抗係数 / 複雑地形 |
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| Research Abstract |
1. Numerical study was made on the bulk heat transfer coefficient for a variety of vegetation types and densities. (1) The bulk transfer coefficients for momentum and heat, Cm and Ch, change with non-dimensional canopy density C*; each has a muximum. (2) The value of Cm is always larger than the value of Ch for a canopy with cm>ch, cm and ch being the drag coefficient and the heat transfer coefficient of an individual canopy element, respectively. (3) The value of C* at which Ch has its maximum value is larger than the value of C* at which Cm has its maximum.
2. Three-dimensional distributions of wind speed and temperature in a V-shaped valley covered with a pasture and scattered shrubs were continuously observed. The vertical profile of potential temperature in the drifted cold layer is represented by a linear function of height.The wind speed below the level of maximum wind does not seriously change with a fetch, but the wind speed in the upper part of the cold layer outstandingly increases with a fetch.
3. The aerodinamic roughness parameter over inhomogeneous ground surfaces, such as cities, rural towns and so on, is determined by analyzing the wind data at AMeDAS observatories in Japan, by making use of Rossby number similarity theory. Ot is founf that the aerodynamic roughness parameter is proportional to the average size of the roughness elements.
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