Spatio-Temporal Distribution Patterns and Population Exposure Risks of Urban Heat Island in Megacity Shanghai, China

摘要: The urban heat island (UHI) effect has been intensifying, which leads to a more severe risk of population heat exposure (PHE). However, there are fewer studies on the UHI ranges and the associated PHE risks, particularly on the fine scale. This study explored the spatial-temporal evolution characteristics of UHI ranges and PHE risks, combined with the temperature attenuation mutation (TAM) method, breakpoint regression model, PHE relative risk assessment model, and spatial autocorrelation analysis. The results showed that the UHI range and the surface UHI intensity in Shanghai was continuously increasing. The overall pattern was characterized by a stable large heat island and new small heat islands that continued to emerage. The PHE risks had been intensifying, with more and more people congregating in high-intensity UHI ranges, and the population covered by these areas had more than doubled. PHE regions of high risk level were primarily concentrated in the central urban areas, showing typical spatial clustering characteristics, while PHE regions of low risk level were mainly dispersed in the peripheral suburbs, and showed a gradual transformation trend into high risk level. This study can provide scientific basis and decision support for precise and refined urban heat risk control and planning management.