Similarities and disparities in urban local heat islands responsive to regular-, stable-, and counter-urbanization: A case study of Guangzhou, China

Abstract Understanding the dynamics and spatial heterogeneity of the intra-city surface heat island (herein termed the surface urban heat island, SUHI) is critical for the design of urban heat mitigation strategies. Large disparities in the spatiotemporal variations of SUHIs are anticipated under different urbanization processes. However, most previous studies have focused solely on the inter-annual spatiotemporal SUHI variations of regular urbanization, while those for stable- and counter-urbanization remain largely unknown. Based on the remote identification of these three urbanization types over Guangzhou, China, we propose a novel strategy to investigate simultaneously the spatiotemporal variations and the associated controls of SUHIs. Our results indicate that: (1) Counter-, regular-, and stable-urbanization occurs mainly over the city center, city periphery, and the in-between areas, respectively. (2) The three urbanization types all demonstrate similar and significant growth in the daytime local SUHI intensity (SUHII). (3) There are significant disparities in the contributions of controls to the inter-annual daytime SUHII trends for these three urbanization processes. For the regular urbanization, the increase of the impervious surface percentage (ISP) dominates daytime SUHII growth, while the combination of ISP and residual factors (e.g., background climate and 3D urban geometry) leads for counter urbanization. For stable urbanization, the combination of residual controls and the increase in population density is the major factor. Urban divisional management may contribute to the mitigation of intra-city SUHI. Our findings potentially advance our understanding of changes in urban thermal environment under different urbanization processes.