RS and GIS-based analysis of urban heat island effect in Shanghai

The urban heat island effect (UHI) has caught great attention with the fast urbanization processes. UHI leads to the worsening environment due to its contribution to intensely high temperature, particularly in the summer. The effect of summer UHI has been concerned in the whole urban ecological system. Taking Shanghai as an example, two distinct ETM+ remote sensing (RS) images are analyzed to show the effect of UHI by converting the gray-scale values of band 6 to pixel brightness temperature. Accordingly, the land surface temperature distribution can be obtained using normalization and density segmentation. And with ENVI software, Arcgis9.3 map study software, the overall characteristics, variability, and related influencing factors of UHI are generalized. The regression analyses between Normalized Difference Vegetation Index (NDVI) and the brightness temperature on local scale in different land cover types reveals a significant inverse correlation between normalized brightness temperature and vegetation level. Also, through the quantitative analysis, Huangpu River has a significant cooling effect on the land surface temperature of Shanghai within a certain special range. Some suggestions to improve the city environment are proposed based on the analysis results and several potential research directions for the city UHI discussed in the end of the article.