A Study on the Urban Growth and Thermal Environmental Changes of Beijing City Based on TM Imagery Data

With the adoption of opening up and reform policy, the space of urban growth of Beijing city has been speeded up and a dramatic influence on its urban environment has been exerted. Urban growth, vegetation area changes and their influence on the thermal environment of Beijing city were analyzed based on the three scenes of Landsat5 TM data acquired on September 26th 1987, August 28th 1994 and August 31st 2001, separately. Radiometric normalization between the three images from different dates was made firstly, followed by information extraction of urban growth and vegetation changes. The generalized single channel algorithm proposed by Jimenez-Munoz J C, et al. in 2003 was applied to retrieve land surface temperature (LST) and thermal environmental changes were examined based on the normalized LST. The result shows that urban growth area coincides with the thermal intensified area and a good correspondence exists between vegetation increased area and thermal relieved area or no change area. The characteristics of urban growth and thermal intensified area changes were similar, both growing from the center of Beijing city to its outside in accordance with the ring road system.