Spatio-Temporal Patterns and Drivers of the Urban Heat Island Effect in Arid and Semi-Arid Regions of Northern China

Investigating the urban heat island (UHI) effect and its driving factors is crucial for supporting future climate mitigation actions and human adaptation strategies. Due to the unique climatic characteristics and vulnerable ecological environment of arid and semi-arid regions, it is valuable to detect the UHI effect in cities in these regions, which have not been fully explored yet. Utilizing moderate-resolution imaging spectroradiometer (MODIS) land surface temperature (LST) data from 2010 to 2020, this study quantified the summer, winter, and annual diurnal mean surface urban heat island intensity (SUHII) of 30 cities in the arid and semi-arid regions of northern China and comprehensively investigated the spatio-temporal patterns and drivers of UHI. The results showed that the annual mean daytime SUHII had a significant decreasing trend, and the nighttime SUHII had an increasing trend for these cities between 2010 and 2020. The nighttime SUHII was stronger than the daytime SUHII, and some cities exhibited surface urban cool island (SUCI) phenomena during daytime, especially in winter. It was also found that cities at higher latitudes experienced higher daytime SUHII throughout the year, and that it was more pronounced in winter. The driving factor analysis revealed that daytime SUHII was primarily influenced by the urban area size (UAS), total precipitation (TP), and the differences in white sky albedo (ΔWSA), enhanced vegetation index (ΔEVI), and normalized difference moisture index (ΔNDMI) between urban and suburban areas. Nighttime SUHII was mainly correlated with ΔWSA, ΔEVI, ΔNDMI, and the differences in elevation (ΔDEM) between urban and suburban areas. This indicated that the background climate was a potential driver for the spatial pattern of UHI in this region. As for the nightlight difference between urban and sub-urban areas (ΔNTL), no correlation was observed with neither daytime SUHII nor nighttime SUHII. These findings are promising in providing theoretical support and scientific guidance for formulating sustainable development strategies and mitigating the UHI effects of cities in the arid and semi-arid regions.