城市扩展强度及其地表热特性遥感定量分析

A Quantitative Analysis of Urban Growth and Associated Thermal Characteristics Using Remote Sensing Data

提出定量确定城市扩展范围及其发展强度的方法——地图密度指数。以中部城市长沙为例,利用Landsat TM/ETM+数据定量评价城市扩张及其热环境特征的变化。首先,集成遥感光谱指数提取地表非渗透表面,然后利用移动窗口算法获得地图密度指数,再根据设定的阈值获得密度指数等级图,依此密度指数等级图识别城市扩展范围及其发展强度。再结合地表温度反演的数据,分析城市格局及其变化与地表热特性变化的定量关系。结果表明,自20世纪90年代以来,长沙市城市区域及其发展密度显著增加,城市发展的密度差异与地表温度相一致。地图密度指数能较好刻画城市扩展范围及其发展强度,并与地表温度空间分布存在较好的对应关系。

This study utilized remote sensing data of Landsat TM/ETM＋ to assess urban sprawl and its thermal characteristics inChangsha of central China. A new approach was proposed for quantitatively determining urban land use extents and development densities. Firstly, impervious surface areas were mapped by integrating spectral index derived from remotely sensed data. Then, map density index were derived by using moving window calculation and selecting certain threshold values. Based on the map density index, the urban land extents and development densities were identified. The urban surface thermal patterns were investigated using Landsat thermal band. Analysis results suggest that urban extent and development density and surface thermal characteristics and patterns can be identified through qualitatively based on map density index and land surface temperature. Results show the built-up area and urban development densities have increased significantly in Changsha since t990s. The differences of urban development densities correspond to thermal effects where higher percent imperviousness is usually associated with higher surface temperature. Map density index and land surface temperature are demonstrated to be very useful sources in quantifying urban land use extent, development intensity, and urban thermal patterns.