Temporal and spatial variations of urban heat island effect in Beijing using ASTER and TM data

More and more questions were emerged with the development of Beijing's urbanization. One of them is urban heat island (UHI) effect. This paper focuses on the monitoring of urban heat island effect with the temporal and spatial change using ASTER and TM data. Our study area is located in the central urban area of Beijing which mainly the area surrounded by the fifth ring road. 4 ASTER images almost in summer in 2001, 2003, 2004 and 2006 were collected, and 2 TM data also in summer in 2002 and 2005 were collected. In order to calculate the urban heat island intensity, the land surface temperatures were retrieved using an iterative way to compare the temperature difference between the urban and surrounding rural area. Based on the relative temperature method, the UHI intensity was obtained for all of the satellite images. The UHI was divided into normal, weak, strong, very strong, severe and extreme by which the temporal and spatial changes of the UHI effect were compared. Generally speaking, the results indicate that the UHI effect was increased with the development of the urbanization. And the extreme UHI effect was occurred in the southeastern part of the Beijing city where almost of the industrial factories were located. The UHI effect in the old city enclosed by the second ring road was generally weak because of the relatively lager areas of water body and grassland.