Impact of land use change on the spatiotemporal evolution of the regional thermal environment in the Beijing-Tianjin-Hebei urban agglomeration

In this study, the Beijing-Tianjin-Hebei urban agglomeration (BTH), one of the three largest urban agglomerations in China, was selected as the study area. The effects of different land use types on the diurnal regional thermal environment of BTH in summer were investigated by using Getis-Ord Gi* index and contribution index. The results illustrated that the spatial distribution of relative land surface temperature (RLST) varied greatly between day and night in summer. The RLST was higher in the northwest and southeast of BTH during the day. At night, the northwest was dominated by cold spots, while the hot spots were mainly located in the southeast. BTH was mainly dominated by cropland, forest, grassland and built-up area. The cropland and built-up area were mainly located in the southeast, while the forest and grassland were mainly located in the northwest. The cropland was the largest, accounting for about 45.5% of the overall area. However, with the urbanization, the cropland decreased by 5.2% and the built-up area increased by 2.3%. In summer, the RLST of land use varied greatly during the day and night. The RLST of water body was below 0 ℃ during the day, which had significant cooling effect on the regional thermal environment. At night, the RLST of the water body was 3~4℃, which had significant warming effect. Grassland has no significant cooling effect in the daytime, but it was stronger than that of forest at night. Through analyzing the diurnal impact of different land use types on the regional thermal environment, this study could help to understand the distribution characteristics and impact mechanism of the regional thermal environment, thus expect to provide a theoretical basis for the formulation of mitigation strategies for regional heat islands. © 2023 Chinese Society for Environmental Sciences. All rights reserved.