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近年来超大城市的下垫面环境发生了显著变化,并对区域生态系统造成了明显的影响。因此有必要定量化下垫面特征参数并研究它们之间的相互关系对城市热环境的影响。以北京市为例,采用2009年6月2日Landsat-5TM卫星影像提取城市不透水层百分比、地表温度、土地利用/土地覆盖和植被指数这些典型地表特征参数,并分析它们之间的定量关系。研究结果表明:随着城市化进程加快,北京市高不透水面扩展到六环,六环以内地表温度保持在40℃以上,特别是商业区等特高不透水面区域地表温度甚至高达45℃,处于城市高温区域,六环以内区域平均温度波动幅度不大。另外,森林和农业用地的降温作用明显,最高降温幅度达到6℃,而且夏季裸土地表温度接近高密度居民区地表温度。
In recent years, the underlying surface environment of megacities has undergone significant changes and has had a significant impact on the regional ecosystems. Therefore, it is necessary to quantify the underlying surface parameters and study the impact of the interrelationship between them on the urban thermal environment. Taking Beijing as an example, Landsat-5TM satellite images on June 2, 2009 were used to extract the typical surface characteristic parameters of urban impermeable layer, surface temperature, land use / land cover and vegetation index, and to analyze the quantitative relationship between them . The results show that with the acceleration of urbanization, the surface water temperature of Beijing high-impermeable surface extends to the sixth ring and the sixth ring within 40 ℃, especially in the commercial areas such as the surface area of ultra-high impermeability even reaches as high as 45 ℃ , In the high temperature area of the city, the regional average temperature fluctuation within the sixth ring is not big. In addition, the cooling effect of forest and agricultural land is obvious, the maximum temperature drop reaches 6 ℃, and summer bare land surface temperature is close to the high density residential land surface temperature.