基于MODIS地表温度的重庆城市热岛研究

Study on Urban Heat Island Based on MODIS Land Surface Temperature in Chongqing

为了揭示重庆市地表热环境时空规律,展示重庆城市热岛的基本特征,利用2002年6月—2014年12月地表温度(LST)与归一化差值植被指数(NDVI)数据,分析了以长江-嘉陵江交汇处为中心、以75 km为半径的区域内LST时空分布及其与NDVI的关系.结果表明:1)LST在年际间呈波动变化,无明显规律性.季节上,LST夏季最高,春、秋季分居第二、第三,冬季最低.月份上,LST在1—8月为上升期,9—12月为下降期,8月为全年最大值,12月为最小值.2)从空间平均状况看,LST值在城中心最大,随着与城中心距离的增加,LST呈先减小后增大的趋势.从格点分布来看,LST分布与地形关系密切,高温与低温镶嵌分布于山体之间及山体之上,高温区多集中分布于长江以北、嘉陵江以东的夹角地带.3)热岛的强度和范围与时节有关,高温时节,热岛范围广、强度强,低温时节,热岛范围小、强度弱.4)LST与NDVI在空间上呈显著负相关关系,基本都通过了0.01的相关检验;在时间序列上二者关系不稳定.

In order to reveal the temporal and spatial regularity of the surface thermal environment and the basic characteristics of urban heat island（UHI） in Chongqing, LST temporal and spatial distribution and the relationship between LST and NDVI in the region were analyzed, which took the place where the Jialingjiang river joins the Changjiang river as the center, with 75 km as the radius. based on the data concerning the land surface temperature（LST） and normalized difference vegetation index（NDVI） during the period from June, 2002 to December, 2014.The results were as follows： 1） LST fluctuated irregularly from year to year. From the perspective of season, LST value was highest in summer, and second and third in spring and autumn respectively, and the lowest in winter. From the perspective of month, the LST value was on the rise from January to August, and on the decline from September to December. The value reached the highest of the year in August and the lowest in December. 2） From the perspective of space average, it was found that the value of LST was the highest in the city center, and then the value rose and declined with the increase of the distance from the city center. From the perspective of the grid distribution, the LST distribution was closely related to the terrain, with the high temperature and low temperature between and on the mountains respectively. The high temperature area was mostly found in the angle zone on the north of the Changjiang river and the east of the Jialingjiang river. 3） The intensity and range of area of the heat island were related to the season and time. When it was hot, the heat island was large and the temperature was very high. While in low temperature, the heat island would not be so hot, and the range of heat would narrow down. 4） LST and NDVI exhibited a significant negative correlation in the space, and mostly passed 0.01 tests. In the time, LST and NDVI were unstably related.