Spatiotemporal dynamic mapping of heat exposure risk for different populations in city based on hourly multi-source data

Explicit dynamic and continuous mapping of heat exposure risk (HER) is a vital support for the long-term livability and sustainable management of cities but is rare given the current lack of precisely matching risk-component data. Here, geographic data (rooftops and elevation) and demographic data, particularly the time-matched air temperature data and mobile signaling data both covering 744 periods in one complete month, were used to develop an HER evaluation framework for urban normal heat scenarios and map hour-by-hour outdoor HER with 250 m spatial resolution across Xiamen, China. The results suggested that the mapping analysis was relevant in recognizing the spatial heterogeneity and temporal variability of HER, as well as the population differences in the HER pattern existing under specific spatiotemporal situations for various age (youth/adulthoods/retirement) and gender (male/female) groups. Notably, contributing to better comprehending the HER configuration, high-resolution spatiotemporal mapping was proved to be effective in clearly identifying the detailed time-series evolution of HER by the novel discovery that the definition of 08:00-21:00 as daytime (21:00-08:00 as nighttime) was more consistent with the actual situation of Xiamen than the definition according to sunrise/sunset. These methods and findings provide new knowledge for the zoning prevention and adaptation strategies of HER.