COMPREHENSIVE SURVEY ON THE EFFECTS OF WATER AND GREEN IN THE FORMATION OF URBAN THERMAL ENVIRONMENT

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Comprehensive surveys on the effects of water and green in the formation of urban thermal environment in summer were carried out and their main results are as follows: (1) Long-term observation of wind direction, wind speed and air temperature was carried out to evaluate the cooling effect of sea breeze. The sift from land breeze to sea breeze causes lowering of air temperature or mitigation of air temperature rising. Its average effect on the lowering of air temperature is 3ﾟC but is different according to the distance from the sea. (2) Multi-point measurements were carried out to compare the thermal environment on a river and streets. The measurements show the river is a passing way of wind and its surface temperature is lower than that on streets by 30ﾟC in maximum. Therefore, the air temperature on the river in sea breeze time is lower than that on the streets by 4ﾟC in maximum. The effect, however, is different according to the distance from the sea. (3) Temperature distributions … More around a large pond were measured when the water was full and when it was drained. Low temperature area is formed on the pond and its vicinity. The pond lowers the air temperature in its outer 200-400m area about 0.5ﾟC. The cooling effect of the pond appears more widely in its leeward area than in windward area (4) Thermal environments in and out of green in parks were measured. The air temperature on green in a park is lower than that on its surrounding streets by 3.5ﾟC in maximum. The area where the view factor of vegetation and that of foliage are large has a tendency that there air temperature becomes low. (5) Numerical simulations of urban wind showed the possibility of predicting urban thermal environment. The simulations were two dimension using Large Eddy Simulation and k-epsilon two equation model. Their boundary condition was the temperature distribution at ground surface and the wind profile calculated by roughness parameters. (6) The temperature distribution predicted by numerical simulations for urban atmospheric boundary layer accorded with measured values. The simulation used single dimensional heat balance equation at ground surface and considered the configuration and distribution of buildings. This simulation method was used for quantitative prediction of urban thermal environment through parameter sensitivity analysis; the changed parameters are the height of buildings, anthropogenic heat, surface covering ratio of water and green. Less