Exploring spatial–temporal evolution patterns of urban heat islands in summer and winter: evidence from a megacity of China

Investigating the urban heat island (UHI) effect across different seasons can reveal the impact of seasonal temperature changes on the urban environment, improve the living standard, and develop feasible measures to mitigate UHI effects. In the study, the land surface temperature (LST) of summer and winter was quantitatively retrieved in a megacity (Shenzhen city) during 2013-2023. Through the standard deviation ellipse, profile analysis and the GeoDetector model, this study systematically analyzed the spatial-temporal evolution characteristics and driving factors of the urban thermal environment in summer and winter. The results showed that summer LST initially decreased and then increased from 2013 to 2023, while winter LST consistently increased. During the study, the summer UHI area decreased, whereas the winter UHI area increased. The LST of green land, wetland, and natural open water were lower than that of cropland, unvegetated land and artificial surface, demonstrating that water and vegetation had a mitigating effect on UHI. Land cover type interactions with normalized difference built-up index (summer) and PM2.5 (winter) have the most significant influence on UHI. This study could provide scientific references for rational urban planning and sustainable urban development.