How does urban form impact surface urban heat island in subtropical high-density cities: An investigation based on local climate zone

Although many studies have examined the impact of urban form on surface urban heat island intensity (SUHII) based on local climate zones (LCZ), the spatial-temporal heterogeneity within and between LCZs remains underexplored. Additionally, there is a need to identify key urban form indicators influencing the thermal environment across different LCZs. To address these gaps, this study investigates the influence of urban form on the spatial heterogeneity of SUHII at a 150 m x 150 m grid scale, focusing on the relationship between the two from the LCZ perspective. Using Macau, a subtropical high-density area, as a case study, this paper calculated urban form indicators, SUHII, and LCZ based on multi-source data. It applied geographically weighted regression (GWR) and geographically and temporally weighted regression (GTWR) models to analyze the spatial-temporal non-stationarity between urban form and the urban thermal environment. Additionally, Geodetector was used to rank the interpretive strength of driving factors within each LCZ class. Results show that SUHII of LCZ 8 is the highest. Comparing three regression models (OLS, GWR, and GTWR), the GWR model demonstrates the best fit for accounting for thermal variations resulting from changes in urban form. The regression performance varies significantly among LCZ classes, particularly between compact and open types. Furthermore, the results of Geodector can serve as references for urban form optimization for cooling communities, according to different contributions of driving factors in each LCZ class. For instance, reducing building density is generally relatively effective in all types of LCZ, and increasing porosity has the most significant and typical cooling effect in LCZ 2. For open LCZs, NDVI is the key factor to improve their thermal environments. This study sheds new light on the spatio-temporal variations of the “urban form-SUHII-LCZ” linkage and provides specific planning recommendations for urban heat mitigation, especially in subtropical high-density cities.