城市热屿的时空变化特征及其与绿地的相关性研究——以南京主城区为例

在全球气候变化的背景下，热岛效应成为城市面临的重要挑战之一，但针对热岛自身组成和分布的时空异质性研究还比较少。以南京主城区2017和2022年的热环境为例，将热岛细分为多个独立的热屿(heat islets)，识别出不同的时空变化类型，并探索城市绿地与热屿变化的相关性。结果表明，破碎与融合是热屿时空变化的主要类型，其中破碎之后热屿的热岛强度会明显降低，而融合类型则正好相反。破碎或融合前后热屿的变化与其中绿地的变化有极显著的相关性。假设其他因素一致的情况下，绿地面积每增加1.00hm2，热屿面积会平均减少14.25hm2，热屿破碎后的数量会平均增加1.86个；绿地面积每减少1.00hm2，就有平均1.51个热屿融合在一起，热屿的面积也会平均增加3.89hm2。根据不同热屿的特征进行针对性的绿地规划布局，能更加有效地降低热岛强度。研究结果有望为缓解城市热岛效应提供新的研究和实践思路。

Spatiotemporal Characteristics of Urban HeatIslets and Its Correlation with Urban Green Space:A Case Study of Central Nanjing

Under the context of global climate change, the urban heatisland effect has become one of the grant challenges in urban area.However, there are few studies on the spatiotemporal heterogeneityof the inner composition and distribution of heat islands. This studytakes the thermal environment of the main urban area of Nanjing in2017 and 2022 as examples, divides the heat islands into multipleindependent heat islets, identifies different types of spatiotemporalvariation, and explores the correlation of urban green space withheat islets heterogeneity. The results show that fragmentation andmergence are the 2 main types of spatiotemporal variation of heatislets, and the urban heat islands intensity of heat islets will decreaseobviously after fragmentation, while the merged islets have theopposite trend. There is a significant correlation between the changesof heat islets and urban green space. Assuming that all else beingequal, when green space increases by 1.00hm2, the mean area ofheat islet will decrease by 14.25hm2, and the number of heat isletswill increase by 1.86 on average. On the contrary, for every 1.00hm2reduction in green space, an average of 1.51 heat islets will mergetogether, and the mean area of heat islets will also increase by 3.89hm2.It indicates that targeted green space planning and layout according tothe characteristics of different heat islets could efficiently reduce theurban heat island intensity. This study is expected to provide novelstudy and practical ideas for the mitigation of urban heat islands.