Impact of human activities on urban thermal environment in Shanghai

The urban thermal environment effect resulted from urban heat island phenomena becomes prominent with the rapid urban expansion, which had adverse effect on the urban environment and the urban sustainable development. Spatial-temporal change of urban thermal environment is relevant to interactions of human activities such as the change of underlying surface, anthropogenic heat emission and environmental pollution. Due to the complexity of factors contributing to urban thermal environment, the routine observing methods and statistical methods are insufficient in acquiring data and analyzing the responses of human activities to thermal environment, especially discerning the major attributors from the others. Fortunately, the remote sensing and GIS can resolve the technical problem effectively, which can quantitatively explore the relationship of spatial-temporal change of thermal environment with human activities. Based on Landsat ETM+ images and taking the urban area inside the ring road of Shanghai as a case study, this paper employed Spatial Principal Component Analysis (PCA) method to analyze the spatial pattern and the influencing factors of urban thermal environment as a substitute of Multi-Criterion Evaluation (MCE) method. The results showed that urban construction density and population density, allocation of industries, types of underlying surface and diversity of urban landscape were the leading factors contributing to the urban thermal environment in the metropolitan area of Shanghai. The linear model including the four independent variables could reveal the response mechanism of human activities on thermal environment in Shanghai. From the model, urban building density and population aggregation were regarded as the most sensitive factors to thermal environment among these factors. Furthermore, the difference in spatial distributions of the main factors formation of the diverse urban thermal environment in different areas. The results would be of value to simulate spatial change of urban thermal environment and even put forward countermeasures to lessen the urban thermal environment intensity for policy makers.