Analysis of Urban Thermal Environment Evolution and Mechanisms Based on Multisource Data: A Case Study of Hangzhou, China

Urban thermal environment (UTE) deterioration seriously affects the production, life, and health of urban residents. Therefore, identifying the spatial and temporal evolution of the urban environment and exploring the main factors that affect the UTE are increasingly urgent and important. This study uses multisource spatial data to analyze the changes in surface temperature and its spatial and temporal differentiation patterns of Hangzhou, China in 2000, 2010, and 2021. Then, factors that are intimately connected to the alterations in the UTE are identified. Based on this, the contribution and impact of the UTE are calculated. The findings indicate that from 2000 to 2021, Hangzhou's urban heat island area has been continuously expanding, with an increase of 622.74 km2. In 2021, the maximum surface temperature difference reached 6.2 degrees C, where the heat island area in the Xiaoshan and Yuhang Districts exhibited the largest increase. Hangzhou's urban heat island space showed a scattering distribution in the northwest-southeast direction. High-temperature areas are concentrated in regions that are characterized by dense industrial and commercial distribution, which display local concentration and overall dispersion. Low-temperature areas are concentrated around vegetation-covered regions and bodies of water. The natural and social factors contribute to the changes in surface temperature within the study area. The contribution of social factors on surface temperature surpasses that of natural factors. The leading factors are landscape patterns, the natural environment, and construction activities. The combined effects of various factors increase the surface temperature by 0.965 degrees C for each unit increase in the combined factors within the study area.