Spatiotemporal patterns of the urban thermal environment and the impact of human activities in low-latitude plateau cities

Abstract

Urbanization intensifies the surface urban heat island (SUHI) effect, impacting the urban thermal environment (UTE). This study focuses on Kunming, a low-latitude plateau city in China, to analyze the spatiotemporal evolution of its UTE using remote sensing data. The Cumulative Human Activity Intensity (CHAI) index, incorporating land use, nighttime lights, population density, GDP, and tourism activities, is introduced to assess human activity’s spatial impact on land surface temperature (LST). Key findings include: (1) The nighttime SUHI effect is more pronounced and spatially concentrated, with stronger LST warming and a northwestward shift of the SUHI core; (2) The impact of human activities on LST shows spatial heterogeneity, with urban areas experiencing stronger warming than suburban areas. Specifically, sparsely built areas (LCZ9) and open low-rise zones (LCZ6) contribute significantly to warming; (3) Human activities more strongly influence nighttime LST, with this effect intensified by the synergistic interaction between topographic and meteorological factors. This study offers a novel approach to quantifying diurnal and nocturnal human activity effects on LST, providing insights for optimizing UTE management.