Effects of 2D/3D urban morphology on land surface temperature: Contribution, response, and interaction

Urban morphology severely affects the intra-urban heat flux transport and thus directly regulates urban thermal environment. Despite previous studies suggested that urban morphology may significantly contribute to land surface temperature (LST), few studies simultaneously discuss the effects of urban morphology on LST in different urban units, particularly in the irregular block scale. Here, we explored the relationships between multi-dimensional urban morphology and LST using the eXtreme gradient boosting (XGBoost) model and the SHapley Additive exPlanations (SHAP) method. Especially, we revealed the interaction of the urban morphological metrics on LST at the block (i.e., irregular size delineated by roads) and the grid scale (i.e., a regular grid size with 200 x 200 m). The results show that the contributions of urban metrics on LST follow the rank of 3D building metrics >2D landscape metrics of impervious surface (IS) > 2D landscape metrics of urban green space (UGS). Average building height (AH) and the percentage of landscape of IS (PLAND_IS) are the most important metrics at the block and the grid scale, respectively. Moreover, some metrics have specific thresholds of the warming or cooling effects, e.g., the cooling effect when AH exceeds 19 m and warming effect when PLAND_IS >49%. Finally, we found that the interaction effects of 3D-3D metrics pairs are stronger than that of 2D-3D metrics pairs. These findings provide useful information for understanding the driving mechanism of the 2D and 3D urban morphology on LST and optimizing the urban morphology for mitigating the urban heat islands effect.