Research on the Spatial and Temporal Characteristic of the Thermal Field in Fast-Urbanizing Area Based on Remote Sensing Image

Based on remote sensing image Landsat/TM6, and supported by GIS, this article studied the Spatial and temporal characteristics of thermal field in Hangzhou since 1991 to 2005. Contrastive analysis was conducted between two phases of remote sensing images on the characteristic of thermal Spatial and temporal change, as well as the thermal change difference of different fractal section. It is indicated: (1) The overall surface brightness temperature showed a rising tendency, the scope of ldquoHeat Islandrdquo increased; the change of urban thermal from 1991 to 2005 showed that only the area of low temperature region reduced, the decrement is 7.401 times 10⁷ m²; while the area of intermediate temperature region, inferior high temperature region and high temperature region all increased, the increase respectively is 9.125 times 10⁶ m², 2.479 times 10⁸ m² and 4.010 times 10⁷ m²; (2) As respect of the spatial expansion direction, in the 15 years from 1991 to 2005, the change of Hangzhou urban thermal field showed the characteristic of ldquooutside expandingrdquo, ldquodispersingrdquo, ldquoassociatingrdquo and ldquoinside digestingrdquo. (3)Fractal dimension manifested well the section change difference of brightness temperature in different urban expansion direction. The research also indicated, the change of landscape pattern in Hangzhou had the uniformity with the change of heat environment ecological effect. And the landscape pattern of urban underlying surface was the primary factor of the characteristic of urban thermal distribution.