Spatiotemporal evolution of urban development and surface urban heat island in Guangdong-Hong Kong-Macau greater bay area of China from 2013 to 2019

As one of the major bay areas in the world, the Guangdong-Hong Kong-Macau Greater Bay Area (GBA) has been experiencing a remarkable urbanization process, accompanied by the deterioration of the thermal environment quality. This study tried to explore how urbanization dynamically and regionally affects the thermal environment, by examining the spatiotemporal variation of the local climate zone (LCZ), the centroid movement of the urban form, and surface urban heat island (SUHI) in GBA during 2013 and 2019. The results revealed that the urban areas have expanded from the central GBA to adjacent cities and the gravity center moved from the urban core to the rural periphery, indicating the ongoing urban expansion in GBA. Meanwhile, the SUHI value was calculated and corresponding spatial association analysis was carried out to clarify the pattern and dynamics of the SUHI spatiotemporal change during the study period. The increased proportion of the slightly high SUHI level and expanded high-high aggregation indicated that the thermal environment of GBA has been heated up. Large increments of SUHI occurred mostly in the areas of non-traditional development and areas with high intensity of urban expansion. These increments were attributed to the land occupation of limited or agricultural development zones for urbanization. This study provides insights into the balance between urban thermal environmental and rapid urbanization. Future researches are recommended to address novel and sustainable urban planning strategies that are able to maintain the required urban growth without deteriorating the thermal environment.