Significant contribution of urban morphological diversity to urban surface thermal heterogeneity

Urban heat island (UHI) effect, exacerbated by global warming, poses significant public health threats and socioeconomic damages. Previous UHI studies have largely overlooked thermal heterogeneity within urban areas, as existing research on urban morphology and intra-city thermal variability is mostly limited to the city scale due to the difficulty of acquiring detailed urban morphology data on a larger scale, which result in a lack of comprehensive global understanding of the relationship between urban morphological diversity and thermal heterogeneity. To address this gap, our study utilized satellite-based land surface temperature (LST) observations and the global local climate zone (LCZ) dataset to quantify the urban morphological diversity and urban surface thermal heterogeneity, and further investigate the relationship between them across 1024 cities worldwide. Our results demonstrate a robust correlation between urban morphological diversity and urban thermal heterogeneity, with urban morphological diversity accounting for a median of 15.40 % and 20.57 % of daytime and nighttime variability respectively. This relationship is further influenced by the regional background climate, shaping the intracity thermal variabilities. Across different climate regimes, an increase in urban morphological diversity is consistently associated with elevated urban thermal heterogeneity in each region of the world. These findings highlight the need for policymakers to address intracity thermal heterogeneity and emphasize the importance of tailored urban heat mitigation strategies that account for urban morphological diversity and local climate conditions.