Analysis about Urban Heat Island Effects of the Cities in Chengdu Plain in China Based on NOAA/AVHRR

The radiation of the 4th channel data of AVHRR used was adjusted. After that, the luminance temperature which is equivalent radiation is acquired through computation. According to a majority of researchers´ procedure, the difference of luminance temperature between urban and suburb was used to stand for Heat Island temperature and expressed by centigrade temperature. We summed up twelve cities´ square Tmax, which stand for the largest Heat Island intensity and analyzed Heat Island dynamic changing rules day and night in Chengdu city, through digital statistics method, plane equivalent lines and three-dimensional methods. The phenomenon of Urban Heat Island and it´s characteristics in Chengdu plain in China have been vividly and macroscopically demonstrated. The conclusions are showed in the following : (1) In Chengdu plain, Urban Hot- island Effect is extremely remarkable, regardless of the city´s scale is big or small. The value of different city´s has correlation with it´s scale. The bigger city´s scale is, the more obvious Urban Heat Island Effect is. (2)Distribution of Heat Island temperature in Chengdu city has multi-centers. In the daytime, about 2 or 3 centers of Heat Island temperature mainly appear outer flank of the second circuit road in the east of the city. At night, the centers of Heat Island temperature appear in the inner region of the first circuit road in the middle of the city, and many inferior centers appear nearby the second circuit road. (3)The Center of Chengdu Heat Island temperature varies diurnally. Namely, the center of Heat Island temperature appears in the east of city in the daytime, and it shifts to the middle of city at night.