Relationship between green areas and air temperature in urban area: a case study using Kasetsart University (Bangkhen Campus), Bangkok

摘要

In urban areas, high air temperature is one of the serious environmental problems that affected people's life including health and comfort. The usage of plant to reduce this problem is one probability to avoid the increment of air temperature. The objective of this study was to investigate the relationship between green areas and the distribution of air temperature. Maximum air temperature in the afternoon and minimum air temperature in the early morning were measured during November 1997 to October 1999 (winter, summer and rainy season) at Kasetsart University, Bangkok, Thailand. It was found that both measured time of the three seasons showed similar result, high air temperature occurred in densely built-up areas while low air temperature appeared in the green areas that congested with tree coverage and grassland. Isotherm pattern in the afternoon showed more complex than in the early morning. Green areas showed negatively related to air temperature in three seasons. In winter, summer and rainyseason, when green area was increased by 10 percent, the reducing of air temperature in the afternoon was similarly lower by 0.71 deg C, 0.68 deg C and 0.69 deg C respectively. While 0.21 deg C, 0.15 deg C and 0.13 deg C were air temperature decrement in the early morning of winter, summer and rainy season respectively. Regarding to the relationship between each coverage element and air temperature in three seasons, tree coverage and grassland showed remarkably effect on reducing air temperature especially in the afternoon. No effect from water surface and bare ground were found on air temperature in both times.