Long-Term Spatiotemporal Heterogeneity and Influencing Factors of Remotely Sensed Regional Heat Island Effect in the Central Yunnan Urban Agglomeration

The urban heat island effect (UHI) has become a major challenge for sustainable urban development. In recent decades, the significant development of urban agglomerations has intensified the complex interaction and comprehensive impact of the UHI effect, but the spatiotemporal pattern of regional heat islands has been poorly understood. Based on the land surface temperature (LST) from 2001 to 2020, this study uses the relative land surface temperature (RLST) method to quantify the regional heat island (RHI) of the Central Yunnan Urban Agglomeration (CYUA) beyond a single city, combines a variety of spatial analysis tools to identify the multi-scale spatiotemporal pattern, and explores the multidimensional driving factors of RHIs. The combined effects of indicators such as urbanization intensity, blue–green space intensity (2D), and building height characteristics (3D) on the mitigation or exacerbation of RHIs are included. The results are as follows: (1) The RHI was significantly enhanced, especially during 2011–2014, when the heat island intensity and influence range expanded rapidly, especially in the core areas such as Kunming and Qujing. (2) The main urban areas of prefecture-level cities have a greater contribution to the RHI, and the intercity heat interaction further intensifies the heat island effect on county-level regions. (3) Different land cover types have different effects on RHI. The human and social factors have a positive effect on the RHI, the blue–green intensity has a strong inhibitory effect, and the cooling effect of blue space is better than that of green space. Topographic and meteorological factors have little influence. To effectively address the challenge of UHI, the CYUA must strengthen the construction of green infrastructure, optimize urban planning, promote energy conservation and emission reduction, and improve climate adaptation planning. This paper discusses the spatiotemporal variation in the heat island effect and the influencing factors from a new regional perspective, which enriches the research content of urban agglomeration thermal environment and improves the research system of the heat island effect.