Impact of urban features on land surface temperature across the diurnal cycle under LCZ framework

High-density megacity cores experience strong diurnal surface urban heat islands, yet the relative roles of three-dimensional (3D) urban form, vegetation, socio-economic activity and topography at the local climate zone (LCZ) scale remain insufficiently understood. Here we combine six high-quality ECOSTRESS land surface temperature (LST) scenes with a block-based LCZ framework to quantify the diurnal dynamics of LST in the compact inner city of Beijing. Random forest models and partial dependence plots are used to assess the relative importance and non-linear marginal effects of 15 two-dimensional (2D) and 3D urban features across four built LCZs. Results show that: (1) ECOSTRESS reveals pronounced diurnal LST cycles, with daytime scenes exhibiting strong inter-LCZ contrasts and intra-LCZ heterogeneity that often approach or exceed the temperature differences between LCZ classes, whereas nighttime temperatures converge to a narrow range because of radiative cooling and thermal inertia. (2) During daytime, 3D urban morphology and surface composition dominate LST variability: building density and height amplify warming in compact LCZ1 and LCZ2, while vegetation-related metrics (NDVI and tree-edge density, ED_T) buffer heat in more open LCZ4 and LCZ5; at night, the influence of physical form weakens and population density, nighttime lights and elevation become comparatively more important. (3) Partial dependence analysis reveals distinct LCZ-specific non-linearities and thresholds—for example, rapidly increasing LST above medium building volume density, and diminishing cooling returns beyond intermediate vegetation levels—highlighting that the same indicator does not exert uniform effects across zones or times of day. By explicitly integrating ECOSTRESS LST with block-scale LCZs and detailed 3D morphology, this study complements existing ECOSTRESS-based UHI research and provides a physically interpretable, planning-relevant framework for tailoring diurnal heat-mitigation strategies in high-density urban environments.