上海市人类活动对热环境的影响

Impact of Human Activities on Urban Thermal Environment in Shanghai

随着城市规模不断扩张,由城市热岛现象而导致的热环境问题不断凸现。城市热环境的时空变化,是下垫面改变、人为热释放和环境污染等人类活动因素相互交织作用的结果。由于城市热环境影响因子的复杂性,传统观测手段和统计方法在获取数据和分析人类活动对热环境响应机制方面存在着局限性。而卫星遥感和GIS技术为人类活动对城市热环境的影响分析提供了技术支撑。选用LandsatETM+影像,以上海市外环内区域为研究靶区,在探讨热环境的空间格局基础上,运用空间主成分分析方法替代传统的多准则判断(MCE)方法,分析了人类活动对城市热环境的影响特征。结果发现,对于上海主城区而言,城市建筑与人口密度、工业区布局、下垫面类型以及城市景观多样性四个因子是影响城市热环境空间格局的主导因子;四个因子的线性模型,较好地模拟了热环境的空间变化,定量揭示了上海城市人类活动对热环境的影响机制。

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.