2000—2018年长株潭城市群城市扩张及其热岛响应

Urban expansion in the Changsha-Zhuzhou-Xiangtan urban agglomeration and its urban heat island effect from 2000 to 2018

城市热岛效应同城市居民福祉息息相关,特别是近20 a我国的中西部城市在快速城市化的背景下,城市扩张进程进一步加快,城市热岛效应的影响也随之不断增加。为探究城市及城市群扩张与城市热岛效应变化的关系,以长株潭城市群为研究区域,利用Boyce-Clark形状指数分析城市扩张进程及空间形态变化。首先,利用基于Google Earth Engine(GEE)平台的实用单通道算法进行温度反演;然后,使用均值-标准差法划分温度等级区并定义和提取城市热岛范围;最后,提取城市重心和热岛重心,采用重心迁移方法分析城市扩张与热岛效应之间的变化趋势。结果表明城市热岛变化与城市群城市扩张趋势一致,研究结论如下:①2015年后长株潭城市群进入高速发展关键时期;②城市扩张是热岛面积增加的主要原因;③城市热岛重心与城市重心迁移趋势基本一致,城市热岛范围增加的方向也同城市扩张方向基本一致。

The urban heat island effect is closely linked with the well-being of urban residents.Rapid urbanization has further accelerated urban expansion.This is accompanied by an increasingly significant urban heat island effect,especially in cities of central and western China in the past 20 years.To explore the relationship between the expansion of cities and urban agglomerations and the changes in the urban heat island effect,this study analyzed the expansion and spatial form variation of cities in the Changsha-Zhuzhou-Xiangtan urban agglomeration using the Boyce-Clark shape index.The land surface temperatures were derived through inversion using the practical single-channel algorithm based on the Google Earth Engine(GEE)platform.The temperature zones with different grades were determined using the mean-standard deviation method,followed by the definition and extraction of the range of the urban heat island effect.The urban center and heat island center were extracted,and the variation trends of the relationship between urban expansion and urban heat island effect were analyzed using the center shift method.The results show that the changes in the urban heat island effect were consistent with the expansion of the urban agglomeration and its cities.The results lead to the following conclusions:①After 2015,the Changsha-Zhuzhou-Xiangtan urban agglomeration entered a critical period of rapid development;②Urban expansion is the primary cause of the increase in the area of urban heat island effect;③The urban heat island center roughly shares the same variation trend with the urban center,and the urban heat island range increases in the direction roughly consistent with the urban expansion direction.