成都市热岛效应及其与下垫面的关系

Heat island effect and its relationship with land use in Chengdu City

城市热岛效应是一种常见的城市气候,影响着城市规划及人民的生产与生活。本文以成都市中心城区为研究区,通过采用Landsat 8 TIRS数据,运用劈窗算法反演成都市中心城区4个时间点的地表温度,并对热岛效应的时空变化及其与下垫面的关系进行了分析。结果表明:劈窗算法在无同步气象观测资料校正大气透射率的情况下精度达到1.6 K;成都市中心城区明显存在热岛效应,其面积约占中心城区面积的30%,且春夏季热岛效应的空间差异性较大;三环外热岛效应较三环内明显,武侯区和双流区之间始终存在一个温度高值区;夏季归一化差异植被指数(NDVI)与地表温度存在显著的负相关关系,这说明可以通过种植绿色植物来缓解城市热岛效应;夏季地表温度与改进的归一化差异水体指数(MNDWI)的相关性不如春季和冬季,因此,夏季用水体来缓解热岛效应可能收效甚微;归一化建筑指数(NDBI)与温度在4个时间点上均呈正相关,这说明人类活动是造成城市热岛效应的原因之一,NDBI是研究城市热岛效应的有效指标。

Urban heat island effect,a typical feature of urban climate,plays an important role in urban planning and people＇s production and life. Based on the Landsat 8 TIRS data,we adopted the split window algorithm to estimate the surface temperature of the central urban area of Chengdu City at four different time points,and then analyzed the spatial and temporal dynamics of heat island effect and its influence factors. The algorithm achieved an accuracy of 1.6 K without synchronous meteorological observation data to adjust the atmospheric transmissivity. There was an obvious heat island effect in the central area of Chengdu,with the area of such lands accounting for about 30% of the total area. The spatial variation of surface temperature in spring and summer was obviously larger than that in winter. The heat island effect out of the third-ring was more obvious than that of the area within it. There was a high temperature area between Wuhou District and Shuangliu District. The negative correlation between normalized difference vegetation index（ NDVI） and land surface temperature（ LST） was the most obvious in summer,suggesting that urban heat island effect could be alleviated by planting green plants. The correlation between LST and modified normalized difference water index（ MNDWI） in summer was lower than that in spring and winter,indicating that water may have limited effect in alleviating urban heat island effect in summer. The positive correlation between normalized difference build-up index（ NDBI）and LST at four time points showed that human activities may be an important cause of urban heat island effect,and thus NDBI is an effective index for urban heat island effect.