1997 Fiscal Year Final Research Report Summary
Analysis of heat and moisture trasfer in urbanized area
| Project/Area Number |
08455226
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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 |
水工水理学
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| Research Institution | University of Tokyo |
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Principal Investigator |
KAWAHARA Yoshihisa University of Tokyo, Department of Civil Engineering, Associate Professor, 工学系研究科, 助教授 (70143823)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUZAKI Hironori University of Tokyo, Department of Civil Engineering, Research Associate, 工学系研究科, 助手 (00272360)
TAMAI Nobuyuki University of Tokyo, Department of Civil Engineering, Professor, 工学系研究科, 教授 (90010818)
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| Project Period (FY) |
1996 – 1997
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| Keywords | urban climate / heat island / water and heat balance / land use / urban canopy / vegetation / anthropogenic heat release / sea and land breezes |
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| Research Abstract |
In the first part, the meteorological data obtained hourly over twenty five years by the Meteorological Agency of Japan and the Tokyo Metropolitan Government were analyzed to detect the trends in temperature and moisture. We found that the daily minimum temperature has been increasing while absolute humidity has stopped decreasing or rather increased recently. Annual balances of water and heat were also studied to confirm the effects of urbanization and annual precipitation on water and heat balances.
In the second part, we developed a three-dimensional regional model that takes into account of complex topography, land use, urban canopies and anthropogenic heat and moisture release. The model is made up of four submodels. That is, a heat conduction model in ground, a heat and moisture balance model at ground surface, a surface layr model that is based on the assumption of constant momentum, heat and mass fluxes and an Ekman layr model that solves a set of equations. Here in the Ekman layr model, we adopted a k-e turbulence model modified for stable statification. Through numerical simulation for summer fine days, it is found that the temperature and humidity are affected by land use, sea breeze and that anthropogenic heat release exerts considerable influence on temperature at night while moisture release from cars and human bodies are of minor role.
The third part is devoted the analysis of water and heat transfer in ground and at ground surface. A physically-based distribution model was developed to understand the hydrological processes involved. The model performance was tested in the middle reach of Tama river and then applied to Tokyo Metropolis from 1992 to 1994 with the mesh size of 1km and time step of a hour. It is made clear that the changes in land use have led to considerable change in evapotranspiration and the Bowen ratio.
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