北京市TM图像城市扩张与热环境演变分析

北京城市规模的扩大,对城市环境的影响越来越显著。本文利用3期TM数据对北京市城市扩展、植被变化及其环境影响进行了分析。首先对图像进行辐射归一化,然后分别提取城市用地扩展信息和植被变化信息。并利用普适性单通道算法反演了地表温度,分析了热环境的变化。结果表明,城市扩展区和热状况加重区具有很好的对应性,而植被增加区则对应着热状况减轻区和热状况基本未变化区。城市扩展和热状况加重具有相似的规律,都是从市中心向外围呈辐射状蔓延,与北京市的环状城市结构相符合。

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 Jiménez-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.