Urban agglomeration has become increasingly important over recent decades; however, little is known about the spatiotemporal patterns and evolution of the surface urban heat islands (SUHI) that have arisen in urban areas. The objective of this study was to monitor the spatiotemporal patterns of such SUHI in the urban agglomeration using dense Landsat time series. Landsat images were collected in the Changsha-Zhuzhou-Xiangtan (CZT) region from 2000 to 2017. The land surface temperatures were calculated using the Google Earth Engine and investigation of SUHI phenomenon. The Mann Kendall test (M-K), Theil Sen Median trend analysis (Sen), Standard Deviational Ellipse, and mean center analysis were applied to analyze the spatio-temporal patterns of SUHI. Results indicated that: 1) SUHI was always more obvious in summer than in the three other seasons. Additionally, the SUHI was always higher in Zhuzhou than in Changsha or Xiangtan. 2) The mean center of the SUHI in the three cities has begun to converge, together with the connectivity of SUHI in the CZT urban agglomeration, which is also gradually increasing. 3) There are spatial disparities in the changes to SUHI. The SUHI in the areas surrounding urbanization and the urban core is increasing and decreasing, respectively. The change in the direction of the increase in the SUHI of the three cities shows movement towards the core of the neighboring city. 4) The main reason for causing this variation is the change of landcover type. 77.103% of all the pixels with an obvious growing SUHI trend has changed to impervious areas. The active factory may influence the changed pattern of SUHI. This study suggests that the SUHI in the urban agglomeration is undergoing aggregation, together with the increasing variation in the urban agglomeration.

近几十年来，城市群已变得越来越重要。然而，对于城市地区出现的地表城市热岛（SUHI）的时空分布和演化知之甚少。这项研究的目的是使用密集的Landsat时间序列监测城市群中此类SUHI的时空格局。收集了2000年至2017年长沙-株洲-湘潭（CZT）地区的Landsat图像。使用Google Earth Engine和SUHI现象调查计算了地表温度。应用Mann Kendall检验（MK），Theil Sen中位数趋势分析（Sen），标准偏差椭圆和均值中心分析来分析SUHI的时空格局。结果表明：1）夏季SUHI总是比其他三个季节更为明显。此外，株洲的SUHI总是高于长沙或湘潭。2）SUHI在三个城市中的平均中心已经开始融合，同时SUHI在CZT城市群中的连通性也在逐渐增加。3）SUHI的变化存在空间差异。城市化周围地区和城市核心区的SUHI分别在增加和减少。这三个城市的SUHI增长方向的变化表明其正在向邻近城市的中心移动。4）引起这种变化的主要原因是土地覆被类型的变化。SUHI趋势明显增长的所有像素中有77.103％已更改为不渗透区域。活跃的工厂可能会影响SUHI模式的改变。