南京市夏季热岛特征及其与土地利用覆盖关系研究

利用南京市7月的Landsat TM热红外波段数据,根据单窗算法反演得到南京市地表温度,讨论了南京市热岛特征,并分析了产生这种现象的原因。通过遥感和地理信息系统相结合,运用Landsat TM数据,提取出南京市下垫面类型,分析了不同地表覆盖类型的热辐射特征并定量地分析了土地利用及植被对地表温度的影响。结果显示,南京市夏季主要存在3个热岛中心,分别是建成区、大厂区和八卦洲。南京城区地表温度明显比郊区地表温度高,通过地表温度对比分析发现,城区平均地表温度比城市边缘和远郊区地表温度分别高出3.5℃和5.7℃,城市热岛效应明显。不同地表覆盖类型的地表温度也有显著差异,从高到低依次为：城镇建设用地、耕地、草地、林地、水体。城镇建设用地与水体的表面温度最大相差14℃。城市地表温度与植被覆盖度具有明显的负相关关系,城市地表植被覆盖度低是城市热岛出现的主要原因,今后应当更加注重城市绿地建设,提高植被覆盖率。

Characteristics of Heat Island in Nanjing and Relationship Between Heat Island and Land Use/cover

Landsat TM thermal infrared band data of Nanjing city in July was used in this study and according to single-window algorithm,the land surface temperature of Nanjing city was obtained.Then the urban heat island characteristic of Nanjing city was discussed and the reason of it was analyzed.Through the combination of the remote sensing and geography information system techniques,the land use/cover types of Nanjing were abstracted.Then the thermal radiation character of different land use/cover was analyzed and the relationship between land surface temperature and land use/cover types,especially plant cover was quantificationally analyzed.The results showed that there were three urban heat island centers in summer of Nanjing,and the land surface temperature in city proper was higher than that in suburban district.Through comparison,the average land surface temperature in city proper was 3.5 ℃ and 5.7 ℃ higher than that in the edge of city and suburban district.Urban heat island effect was very distinct.The land surface temperature of different land cover types had great discrepancies,which were urban built land,farm land,grass land,forest land and water from high to low in order.The land surface temperature can reach 14 ℃ between urban built land and water.There was evident negative relationship between land surface temperature and vegetation cover rate,the lower land cover rate was the main reason to urban heat island.