关键词: 城市热岛效应, LightGBM模型, Shapley加性解释（SHAP）, “源－汇”尺度, 季节, 局地气候区（LCZ）

Abstract:

As a key indicator for measuring the urban thermal environment, the spatiotemporal heterogeneity of land surface temperature (LST) and its driving mechanisms have become major research directions. Traditional linear models exhibit limitations in analyzing the nonlinear dynamic characteristics of thermal environment systems, whereas the LightGBM model combined with the interpretable Shapley Additive exPlanations (SHAP) algorithm provides a novel approach for uncovering complex driving mechanisms. Addressing the shortcomings of existing research regarding the quantification of “source-sink” scale landscape effects and the analysis of seasonal dynamic mechanisms, this study innovatively constructs a two-dimensional “season-source-sink” analytical framework based on Local Climate Zones. Taking the main urban area of Jinan City as the study area and integrating multi-source remote sensing and geospatial data, this study investigated the coupled influence mechanisms of urban spatial form, natural environmental factors, and human activities on LST. It quantitatively analyzed the contributions of nine types of driving factors to LST within "source-sink" landscapes across the four seasons. The findings revealed that natural environmental factors play a dominant role in regulating the urban thermal environment, with the Digital Elevation Model, Normalized Difference Vegetation Index, and Modified Normalized Difference Water Index identified as key regulatory factors. Although the impact of urban spatial form on LST is less pronounced than that of natural environmental factors, elements such as the Floor Area Ratio, Sky View Factor, and Building Coverage Ratio exert significant effects. The influence of human activities on LST was relatively minor; however, point data and Road Density exhibited certain impacts at the local scale. These findings provide strategic recommendations for differentiated planning in different seasons and source-sink areas, offering a scientific basis for managing urban thermal environments in the future. It is essential to fully utilize natural environmental resources and rationally plan building layouts to optimize the urban thermal environment and enhance the urban ecological livability of cities.

Key words: urban heat island effect, LightGBM model, shapley additive exPlanations (SHAP), “source-sink” scale, season, local climate zone (LCZ)