北京市六环内区域城市绿地对地表温度降温效益的差异性

Differences in Land Surface Temperature Cooling Effect of Urban Green Space within the Sixth Ring Road of Beijing

城市化进程加剧了热岛效应,研究不同绿地降温效益的差异性可为规划设计提供合理依据。文中选取北京市六环内区域作为研究对象,对2017年Landsat影像进行遥感解译、地表温度(LST)反演以及归一化植被指数(NDVI)计算,并单独提取绿地部分的地表温度;针对下垫面覆盖类型中的绿地部分,基于GIS网格法,将研究区划分不同尺度的网格,分别计算每个网格对应的景观指数CA、LSI、ED、PD、ENN-MN、AI以及NDVI平均值,并分析各景观指数以及NDVI均值与地表温度之间的关系。结果表明:绿地的面积越大、形状越简单、绿地越完整、连接度越高、空间分布聚集程度越高、NDVI值越高,其地表温度越低、降温作用越好;此外,不同城市绿地由于其自身的地理位置、植被类型等因素的影响,其地表温度在空间分布上也表现出一定差异性和规律性。

The urbanization process has exacerbated the urban heat island effect. As green space is a subsurface element with cooling effects, the study of the differences in the cooling effects of different green spaces can provide a reasonable basis for planning and design. With the area within the Sixth Ring Road of Beijing as the research object, the paper interprets the Landsat remote sensing images in 2017, calculates inverse surface temperature and normalized vegetation index(NDVI), and extracts the surface temperature of the green spaces separately. For the classification of green spaces in the subsurface cover type, CA, LSI, ED, PD, ENN-MN and AI landscape indices are calculated based on the GIS grid method, and the relationship between each landscape index and the relationship between NDVI and surface temperature are analyzed. The results show that the larger green spaces, the simpler the green space shape, the higher the integrity, the connectivity, the spatial distribution and concentration of green spaces, and the higher the NDVI value, but the lower the surface temperature and the better the cooling effect. In addition, different urban green spaces present certain differences and regularity in the spatial distribution of their surface temperature due to the factors such as their own geographical location and vegetation types.