1994 Fiscal Year Final Research Report Summary
study on the effect of urban rivers on micro climate in surrounding region
| Project/Area Number |
05452244
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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 |
水工水理学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
IKEDA Syunsuke Tokyo Institute of Technology Faculty of Engineering Professor, 工学部, 教授 (60016590)
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| Co-Investigator(Kenkyū-buntansha) |
IZUMI Norihiro Tokyo Institute of Tecnology Faculty of Engineering, Research Associate, 工学部, 助手 (10260530)
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| Project Period (FY) |
1993 – 1994
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| Keywords | micro climate / urban rivers / meteorological field observation / heat budget / heat island / cooling effect of atmosphere / sea wind and land wind / heat environment |
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| Research Abstract |
(1) When wind blows across rivers, internal boundary layrs develop in channels and the lower portion of the wind is cooled on water surfaces and flood plains. This cooling effect reaches 30 m high in our observation. The intrusion of this cooled wind results in the drop of temperature in urban areas.
(2) Heat exchange between the atmosphere and flood plains is maximized in the daytime, and it is larger when sea wind blows than land wind does. In addition, the heat exchange is correlated to the drop of temperature in urban areas around rivers.
(3) Heat budget on flood plains and water surfaces in urban rivers is studied. Latent heat is dominant in flood plains, while heat storage is dominant in water surfaces. These are the main processes of the cooling effect of rivers.
(4) Under the assumption of hydrostatic pressure, the atmospheric flow in the internal boundary layr is modeled. Numerical simulations are performed to predict wind velocities, temperature and humidity distribution. The predicted results agree well with the observed data.
(5) In tidal rivers, heat budget is strongly effected by the movement of water body. The temperature is oscillating due to tides. It is observed that water temperature in tidal rivers is more uniform than lakes. The temperature difference between surface water and bottom water is as small as 1.5 degrees Celsius. This small difference of temperature increases the cooling effect of rivers.
(6) A numerical model to predict the cooling effect of water surfaces and greenbelts in urban areas is proposed. The simulation using this model can suggest the arrangement of water surfaces and greenbelts in urban areas.
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