南京市冷/热岛格局的尺度效应研究

Study on the Scale Effect of the Cold/Heat Islands Pattern in Nanjing

城市地表覆被类型变化影响城市热环境的空间格局,研究城市地表覆被类型与城市冷/热岛格局的相关关系,对调节城市微气候,改善人居环境,提高城市韧性具有重要的意义。基于landsat8影像数据,提取南京市4种主要地表覆被类型(水体、植被、不透水面、建筑)的参数;同时利用热红外波段反演地表温度,分别从像元(小)和市、区级行政区划(大)2个尺度,研究冷/热岛空间分布与主要地表覆被类型之间的关系并就其尺度效应进行了深入探讨。研究结果如下:基于像元尺度的空间分析表明,植被和水体的分布与冷岛空间格局具有相关性;不同地表覆被类型的降温效应顺序为:水体>植被>不透水面>建筑;建筑和不透水面的分布与热岛空间格局具有相关性。基于市、区级行政区划尺度的空间分析表明,4种地表覆被类型与冷岛效应相关性较低;建筑与不透水面与热岛效应相关性较高,其中建筑与热岛效应相关性最高(R^(2)=0.95)。总体而言,基于小尺度的研究能反映地表覆被类型与冷/热岛空间分布的相关关系,而基于大尺度的研究则从数据统计的角度反映城市热环境的综合特征。研究有助于城市规划者理解城市冷/热岛形成的尺度特征,为应对全球气候变化,合理规划城市布局,促进城市可持续发展提供参考。

Changes in urban land cover types affect the spatial pattern of urban thermal environments,and the relationship between urban land cover types and urban cold/heat island patterns is of great significance for regulating urban microclimate,improving human settlements and improving urban resilience.Based on the landsat8 Satellite imaging data,the parameters of the four main types of land cover(water,vegetation,impervious surface,building)in Nanjing were extracted,at the same time,the surface temperature was retrieved using the thermal infrared band.The relationship between the spatial distribution of cold/heat islands and the main land cover types was studied from two scales:pixel(small)and city and district administrative division(middle),and the scale effect was discussed in depth.The results are as follows:The spatial analysis based on the pixel scale shows that the distribution of vegetation and water is related to the spatial pattern of cold islands;the order of cooling effects of different types of surface types is:water>vegetation>impervious surface>building;the distribution of buildings and impervious surfaces is related to the spatial pattern of the heat island.The spatial analysis based on the scale of administrative divisions of cities and counties shows that the four types of land cover have a lower correlation with the cold island effect;buildings and impervious surfaces are highly correlated with heat island effects,and in particular,buildings and heat island effects have the highest correlation(R^(2)=0.95).In general,research based on small scale can reflect the correlation between surface cover types and spatial distribution of cold/heat islands,while research based on mesoscale reflects the comprehensive characteristics of urban thermal environment from a statistical perspective.The research can help urban planners understand the scale characteristics of urban cold/heat island formation,and provide a reference for coping with global climate change,rationally planning urban layout,and promoting sustainable urban development.