基于混合光谱分解的兰州城市热岛与下垫面空间关系分析

Spatial Research on Urban Heat Island and Underlying Surface Using Spectral Mixture Analysis

利用Landsat ETM+数据,采用混合像元线性光谱分解方法提取的城市植被覆盖度与不透水面表征城市下垫面,通过单窗算法反演地表真实温度,对兰州市中心城区的夏季城市热岛强度与城市下垫面的空间分布关系进行相关分析。结果显示,利用中等分辨率ETM+影像对兰州中心城区不透水面和植被盖度分布提取,其成本较低,精度令人满意;兰州城区植被覆盖、不透水面与热岛强度的分布呈空间正自相关,地表温度的空间依赖性极强,与植被盖度和不透水面在空间方向上的相关性差异较大。

The relationship between urban heat island and underlying surface was analyzed based on Landsat ETM＋ data by combining mathematical statistics with spatial statistics. Impervious surface distribution together with vegetation and soil cover,is estimated through a constrained linear spectral mixture model using Landsat ETM＋ data within the metropolitan area of Lanzhou municipality in China. Four endmembers,low albedo,high albedo,vegetation and soil are selected to model complicated urban land cover. Estimation accuracy is assessed using root mean square（RMS）error and color aerial photography. The urban underlying surface was represented by green vegetation and impervious surface generated by the linear spectral mixture analysis while the urban heat island strength was represented by land surface temperature retrieved from the thermal band. Results suggest that impervious surface distribution and green vegetation can be derived from remotely sensed imagery with promising accuracy;a positive spatial autocorrelation exists in the distribution of green vegetation,impervious surface and heat island strength in Lanzhou City.