基于遥感影像的合肥市热岛效应时空变化特征及成因

Spatiotemporal variation characteristics and causes of urban heat islands in Hefei City, Anhui Province of China based on remote sensing.

利用1995年、2002年和2010年3景Landsat TM/ETM+遥感影像的热红外波段数据反演合肥市地表温度,并对地表温度值进行标准化处理,利用标准差分类法得到地表温度等级图。再结合归一化植被指数、土地利用/覆盖类型和社会经济发展数据,对合肥市热岛效应的时空变化及影响因素进行了分析。结果表明:合肥市热岛效应总体呈现出东北—西南高、东南—西北低的空间特征,强热岛效应地区主要集中在老城区并不断向东部和南部新兴工业区扩展,表现出多中心的片状分布新特征。1995—2010年合肥市热岛空间分布与延展基本与城市建成区的布局相一致,热岛范围不断扩大,高温区、极高温区所占面积比例不断减少,热岛强度呈减弱趋势。LST与NDVI存在明显的负相关性,建设用地均温最高,耕地、林地次之,水体最低。建设用地处于地温等级最高的3个等级中,对热岛效应的贡献最大,水体和林地对降低城市地表温度的作用最为稳定。

The thermal infrared band data of Landsat-6 TM/ETM images acquired in 1995, 2002 and 2010 were used to invert the land surface temperature of Hefei. The values of the land surface temperature were normalized, and the grading figure of the land surface temperature was obtained through the standard deviation taxonomy. Furthermore, the NDVI, land-use/land-cover change, and social economic development data were used to analyze the spatiotemporal variation and its causes of heat island effect in Hefei. Overall, the urban heat island effect in the city pres- ented a spatial pattern of being higher in northeast-southwest and lower in southeast-northwest. The areas with strong heat island effect were mainly concentrated in the old city, and extend to the eastern and southern new industrial areas, showing a new characteristic of multi-center and patchy distribution. In 1995-2010, the spatial distribution and extension of the heat islands were basically in consonance with the layout of the urban districts in Hefei. The scope of the heat islands was expanding, but the proportions of high temperature area and extremely high tempera- ture area were declined. The intensity of the urban heat islands exhibited a decreasing trend. There existed an obvious negative correlation between the LST and NDVI. The construction land had the highest average land surface temperature, followed by the farmland and woodland, and by the water body. The construction land had the priority position in the highest three grades of land surface temperature, which made a great contribution to the heat island effect. The water body and woodland played the most stable role in reducing the urban surface temperature.