Resolving Surface Heat Island Effects in Fine-Scale Spatio-Temporal Domains for the Two Warmest Metropolitan Cities of Korea

The urban heat island (UHI) has been a critical social problem as urbanization intensifies worldwide, significantly impacting human life by exacerbating heat-related health issues, increasing energy demand for cooling and the associated environmental problems. To accurately assess the risk of heat intensification for human health and ecosystem, it is important to quantify the significance at specific times and locations. However, there have been little analyses that capture both the diurnal and spatial variations due to the limitations of traditional satellite datasets. This study investigates the fine-scale spatio-temporal behaviors of the heat island effect in Korea's most heat-impacted metropolitan cities, by utilizing relatively new land surface temperature (LST) data: ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS). The analysis demonstrated that our high-resolution assessment revealed surface urban heat island (SUHI) intensities during summer to be 5–8 ℃ higher compared to those derived from coarse-resolution data. The intensification rates by land uses were also quantified with greater accuracy, showing that industrial areas experienced changes of up to roughly 2 ℃/hour during the early morning in summer. The spatial characteristics of heat intensification were examined across various land use types, revealing that densely clustered urban land uses can amplify heat intensification, with industrial areas experiencing a doubling effect.