Spatiotemporal Patterns and Drivers of Summer Heat Island in Beijing-Tianjin-Hebei Urban Agglomeration, China

The surface urban heat island (SUHI) phenomenon, arising from rapid urbanization, has become a crucial research topic across various fields due to its adverse impacts on the natural environment and human well-being. This article investigated the spatiotemporal patterns of summer SUHI from 2001 to 2018 in Beijing-Tianjin-Hebei (BTH) urban agglomeration, China. On this basis, it examined the influence of natural and socio-economic factors on summer SUHI using the spatial regression model and ordinary regression model. We found that the mean summer SUHI intensity in August was the highest at 0.76 °C, followed by July and June (0.57 °C and -0.08 °C, respectively). The spatiotemporal trend analysis revealed that the summer SUHI intensity of more than one-third of districts and counties (68 of 200) had significant increasing trends from 2001 to 2018. The largest significant increasing trend was observed in Dongli District, Tianjin (0.17 °C/year). Besides, most of the high SUHI were dispersedly located in the southeast plain areas, while low SUHI were mainly congregated in the northwest mountain areas. For the relationships between summer SUHI intensity and drivers, different models have different goodness of fit. Compared with the ordinary regression model, the spatial regression model performed better. The optimal model indicated that the proportion of impervious surface and air temperature should play the leading role in the summer SUHI intensity. The findings are of great help for understanding the dynamic features of the summer SUHI and provide a theoretical basis for optimizing urban agglomeration planning.