Joint associations of 2D–3D urban form with land surface temperature along an urban–rural gradient: Implications for sustainable urban planning

As fundamental urban units, buildings are closely associated with urban thermal environments, and their morphological attributes are related to spatial variations in thermal conditions. Although significant progress has been made in characterizing building morphology, the relative importance and joint associations between 2D horizontal characteristics and 3D vertical structures in shaping neighborhood-scale thermal environments along urban-rural gradients remain underexplored. This study integrated multi-source remote-sensing data and Geodetector analysis to examine the joint, grid-level associations of 2D and 3D urban-form indicators with land surface temperature (LST) in Hangzhou, China. Multi-temporal LST data from 2000, 2010, 2015, and 2020 were used to characterize the thermal context, whereas the building-morphology data in 2020 supported a cross-sectional spatial association analysis. The results revealed clear spatial variation in the relative explanatory power of morphological indicators. Specifically, 3D building configurations exhibited the greatest explanatory power in the Core Built-up Area, whereas 2D characteristics showed stronger associations with LST in the Suburban Built-up Area. Interactions between 2D and 3D features generally provided greater explanatory power than individual factors, with several factor pairs showing nonlinear enhancement. These findings highlight the value of jointly considering horizontal land-cover patterns and vertical building form when assessing urban thermal environments. By elucidating gradient-specific thermal regulation processes and multidimensional interactions among built-environment features, this study provides a scientific foundation for spatially targeted, climate-responsive heat mitigation strategies and sustainable urban development.