Simulation of the Influence of Urban Green Areas with Various Scales and Allocation

Abstract

In this study a two dimensional k-ε two equation model was used with the equations of temperature and normalized humidity to analyze the thermal effect of urban green areas. The relation between the scale of an urban green area and its influence and the relation between the interval of an urban green area and its influence were analyzed. The relation of scale of a green area and its influence on the surrounding urban area is not clear, although many micrometeorological measurements of urban green areas have indicated that a large scale of green area influences a large urban area. The relation of the interval between green areas and its effect on the surrounding urban area is also unclear. With respect to the relation between scale of urban green area and its influence, at the lowest simulated altitude of 2 m sudden decreases in temperature and sudden increases in normalized humidity were observed at the upwind edge of green areas. In the adjacent urban area downwind of green areas, rapid increases in temperature and rapid decreases in normalized humidity were found. At the height of 6 m, the changes were smoother. From the distribution of temperature and normalized humidity, it is observed that a green area of larger scale influences a higher area. From the distribution of diffusivity, a large value was observed at the transition area from green area to urbanarea and this tendency was the same in the case of two green areas. On the relation of interval between green areas and its influence, low temperature and high humidity were observed in the urban area between two green areas. These results show that the two green areas with optimal interval affect the temperature and humidity near the ground effectively. © 2000, The Society of Agricultural Meteorology of Japan. All rights reserved.