Comparing the Spatial and Temporal Evolution of Land Surface Temperature and Driving Factors in Chinese 19 Urban Agglomerations

China has experienced rapid expansion of urban agglomerations (UAs) in the past decades, whose negative influence affected the sustainable development of the ecological environment. However, few studies explored the long-term evolution features of these UAs and their thermal effect at the national scale by comparing UAs with different sizes. This study employed MODIS land surface temperature (LST) data to analyze the spatial and temporal evolution characteristics of LST from 2000 to 2020 and investigated its potential underlying mechanisms. The results indicated that the urban heat island (UHI) effect in urban areas was predominantly concentrated in core cities and their surrounding areas. A 10% increase in Urban Agglomeration Built-up Area Intensity (UABI) of national-level, regional-level, and city-level UAs resulted in a corresponding LST change of 1.33°C, 1.15°C, and 1.71°C, respectively, demonstrating a marginal effect. The dominant driving factors were quite different among different level UAs with the help of Geo-detector analysis. Usually, UABI and Gross Domestic Product (GDP) were the primary driving factors of LST in UAs, while Population density (POP) and Night light index (NLI) exhibited weaker effects. However, the in-tersection of UABI and Normalized Difference Vegetation Index (NDVI) has the most significant impact on LST in national-level UAs, while UABI and Digital Elevation Model (DEM) played a crucial role in both regional-level and city-level UAs. The decrease of LST was primarily influenced by the intersections of POP with NDVI. These findings aimed to provide a robust scientific and theoretical basis for mitigating the UHI effect in UAs, thereby promoting sustainable urban de-velopment.

近数十年来，中国城市群（urban agglomerations, UAs）经历了快速扩张，其负面效应已对生态环境的可持续发展构成制约。然而，当前鲜有研究在全国尺度下，通过对比不同规模的城市群，探究此类城市群的长期演化特征及其热环境效应。本研究采用MODIS地表温度（land surface temperature, LST）数据，分析了2000—2020年地表温度的时空演化特征，并对其潜在驱动机制展开了深入探究。研究结果表明，城市区域的热岛（urban heat island, UHI）效应主要集中于核心城市及其周边辐射区域。国家级、区域级与城市级城市群的建成区强度（Urban Agglomeration Built-up Area Intensity, UABI）每提升10%，对应的地表温度分别升高1.33℃、1.15℃与1.71℃，呈现出边际效应特征。借助地理探测器（Geo-detector）分析可知，不同层级城市群的主导驱动因子存在显著分异。通常而言，城市群地表温度的核心驱动因子为建成区强度与国内生产总值（Gross Domestic Product, GDP），而人口密度（Population density, POP）与夜间灯光指数（Night light index, NLI）的影响相对较弱。但国家级城市群的地表温度受建成区强度与归一化植被指数（Normalized Difference Vegetation Index, NDVI）的交互作用影响最为显著；区域级与城市级城市群则主要受建成区强度与数字高程模型（Digital Elevation Model, DEM）的共同驱动。地表温度的降低则主要受人口密度与归一化植被指数的交互作用驱动。本研究结果旨在为缓解城市群热岛效应提供坚实的科学与理论支撑，进而推动城市的可持续发展。