基于TM的重庆市主城区热岛效应及其影响因子分析

Remote Sensing of the Spatial Pattern of Urban Heat Island Effects and Its Influencing Factors Using TM Data: A Case Study in Core Areas of Chongqing City

利用2008年TM影像,提取重庆市主城区土地利用信息;提取NDVI(植被归一化指数),结合野外调查,获取反映地表植被覆盖状况的植被覆盖度数据;根据第6波段(热波段)获取地表亮温数据,分析重庆市主城区热岛效应.利用GIS空间分析及数理统计方法,对土地利用类型、城市绿地和城市水体3种影响因子进行分析.结果表明重庆市主城区热岛效应明显,在空间上呈大片、连续分布状态,土地利用类型数据显示这种现象与城市快速扩张密不可分.不同地表覆被类型对地表温度的响应不一致,建设用地最容易产生热岛效应,植被和水体则有着明显的减缓效应.热岛效应与植被覆盖度成呈明显负相关,随着植被覆盖度的提高而降低,试验结果显示它在植被覆盖度高于50%后消失;城市绿地面积越大,内外温差也越大,从而形成热岛中的"冷岛".水体均温比绿地低2℃,表明对于热岛效应的缓解,它比植被更有效,是最直接、有效的影响因子.

Understanding the spatial pattern of the urban beat island（UHI） and its influencing factors is crucial for improving the eco-environment of cities. This study aimed to investigate how land use, urban greenland and water body affect the spatial pattern of UHI using TM data in core areas of Chongqing City. The normalized difference vegetation index （NDVI） and land surface brightness temperature （thermal band, band 6 ）was obtained from the TM data to analyze the UHI. Then, with the combination of field survey and the land use types, the relationships between UHI and land use, urban greenland and water body were explored by GIS and corresponding mathematical statistics. The results show that the UHI is wide distributed. The spatial pattern of UHI is closely related to land use and is consistent with the trends in rapid urban expansion. In addition, different land cover types demonstrate various responses to bright temperature. The construction /and is easiest to lead to UHI, while vegetation and water body effectively slow down UHI. The UHI decreases along with the increasing vegetation cover and will disappear if the fractional vegetation cover is greater than 50%. The greater the fraction of urband greenland is, the more prominent is the different temperature within the UHI, cool island. The water temperature is two degree forming lower than urban greenland on average thus urban water body is relatively the most direct and effective method to slow down UHI. the and