How urban spatial characteristics impact surface urban heat island in subtropical high-density cities based on LCZs: A case study of Macau

Although numerous studies have explored the influence of urban spatial characteristics (USC) on surface urban heat island intensity (SUHII) from the perspective of local climate zone (LCZ), the spatio-temporal heterogeneity within and between LCZs has not been demonstrated. In this study, a total of 1540 grid units in Macau across 7 years were screened as the research samples. USC, SUHII and LCZ were calculated and derived from multi-source data. GWR and GTWR models were applied to detect the spatio-temporal non-stationarity between USC and SUHII, and Geodetector was used for ranking the interpretation strength of driving factors in each LCZ class. Results show that SUHII in LCZ 7 and LCZ 8 is the highest. Besides, the GWR model had the best fitting degree in accounting for thermal variations due to urban form changes, and the regression performance was generally different among LCZ classes, especially between the compact-types and the open-types. Furthermore, strategies related to urban form optimization were finally proposed in each LCZ class based on the contribution of driving factors. This study sheds new light on the spatio-temporal variations of "USC-SUHII-LCZ" linkage and provides specific planning recommendations for thermal environment improvement, especially in subtropical highdensity cities.