城市热岛效应的卫星遥感分析

An Assessment of Urban Heat Island Effect Using Remote Sensing Data

利用MODIS资料研究了2004年4月南京城市热岛特征及其影响因子,结合地表覆盖类型分析了植被归一化指数(Normalized Difference Vegetation Index,NDVI)、地表温度(ts)、地表反照率(α)的城乡差异及其相互关系,探讨了城市热岛(Urban Heat Island,UHI)效应形成的机制。结果表明:南京城区存在着明显的城市热岛效应;城市平均ts比乡村高约10.83%;城市NDVI和α分别比乡村低约为62%和18.75%;NDVI与ts呈负相关,相关系数为-0.73,而NDVI与α之间关系与波段有关;城乡植被覆盖差异是造成UHI的主要原因,其次是地表反照率。

Characteristics of the urban heat island（UHI） effect of Nanjing and its cause are investigated by using the MODIS data in April 2004. The surface parameters from the MODIS data include surface temperature （ ts ）, albedo （ α）, and normalized difference vegetation index （NDVI）. Their heterogeneities over urban and rural area are analyzed based on land cover classification, and their relations are also presented in order to explain the UHI effect. The results show that there exists obvious UHI effect, ts over urban areas are 10. 83 % higher than those over rural areas,and NDVI and ot over urban areas are by 62 % and 18. 75 % less than those over rural areas, respectively. Surface temperature has significantly negative correlation with NDVI and their correlation coefficient is -0. 73. Correlation between NDVI and albedo depends on spectrum of light. Difference in vegetation cover is the primary cause for UHI effect.