关键词: 城市热表面, 剖面线分形, 意义, 上海

Abstract:

The urban thermal environment is dependent strongly on human activities, atmospheric condition and heat transmission etc, which make the urban thermal surface rather complex. As the heat distribution and transmission differ in various land covers, the traditional method such as providing model for forecasting or setting spots to observe variations is not enough to describe the structural and potential factors of thermal environment. It is also found out that the radiation geometry and the properties of the surfaces contribute more to thermal phenomenon. With the development of the spatial geosciences, remote sensing technique is used well to study urban environment. In order to reveal the thermal properties of the surfaces and the urban heat island (UHI) in Shanghai, China, land surface temperature was derived from Landsat ETM+ thermal infrared image dated on 14th June 2000. Considering the spatial distribution of land surface temperature as “thermal surface”, the fractal dimension was computed through profile line fractal method in eight directions. It is revealed that there is an evident fractal character for urban thermal surface profiles. The fractal dimensions in eight directions are between 1.530 0 and 1.780 6, which reveal the complexity of different thermal profiles. By analyzing the factors to UHI, thermal fractal characters are mainly due to the scope and shape of builtup area and land surface properties.

Key words: urban thermal surface, profile line fractal, significance, Shanghai City