Identifying the coupling mechanisms between land surface temperature and urban physical form in Chengdu’s five central districts

Urban thermal environment is a significant impact of human activities on the Earth's system. Understanding the relationship between thermal environments and urban physical form (UPF) at the block scale and proposing planning strategies is crucial. This study focuses on the five districts of Chengdu, using blocks as the analytical unit. It employs the radiation transfer equation method to invert land surface temperature (LST) and constructs a UPF index system from three aspects: land cover, building morphology, and road traffic. Using exploratory spatial data analysis and coupling coordination model, the study reveals the spatiotemporal evolution of LST and UPF and their dynamic-static coupling coordination relationship. The results show that the static evolution of LST and UPF exhibits spatiotemporal differences. LST showed a trend of "rise-then-fall", with its spatial distribution evolving from a "center-low, surroundings-high" to a "center-high, surroundings-low"; UPF showed a continuous upward trend, maintaining a "center-high, surroundings-low" pattern. The dynamic changes display a "central stability and peripheral fluctuation". The static coupling degree showed a general upward trend, primarily in the adaptation stage, while the dynamic coupling degree fluctuated significantly. The static coupling coordination degree presented an overall downward trend, with core blocks mainly in the adaptation phase and peripheral blocks in the antagonistic phase. The dynamic coupling coordination degree was generally lower than the static one, dominated by low-level coupling coordination, and characterized by "mild short-term fluctuations and pronounced long-term variability". The findings provide scientific evidence for climate-adaptive planning in Chengdu.