Study on the influence mechanism of urban environmental factors on thermal environment based on machine learning method
摘要
Focusing on the core area within Xi’an’s Second Ring Road, we integrate built-environment, street-view, and human-activity data and propose an explainable pipeline (TabPFN–SHAP → K-means, k = 4) to uncover nonlinear effects and interactions on land surface temperature (LST) and to delineate differentiated governance units. In model benchmarking, TabPFN achieves the best generalization on the test set (R² = 0.650 ± 0.038, MAE = 0.871 ± 0.041, MSE = 1.482 ± 0.153). Tree-based models fit the training data extremely well (R² ≥ 0.99) but generalize poorly (test R² = 0.326–0.415; ΔR² ≥ 0.25), indicating overfitting. SHAP global importance shows built-environment factors dominate: building density (BD = 31.8%) strongly warms LST; building height (BH = 18.6%) cools; road density (RD = 11.6%) has an inverted-U sensitivity (≈ 800–1300). Population density (PD = 13.8%) turns positively related at high levels. In street views, the green view index (GVI = 11.5%) is strongly negative to LST with a threshold ≥ 0.15 and a cooling band of 0.20–0.35; the sky view index (SVI = 5.2%) is weakly positive; higher IEI and BCR intensify heating. K-means yields four thermal clusters validated by spatial autocorrelation (Moran’s I = 0.303, z = 21.02, p < 0.001), with net SHAP effects of − 1.10, + 0.06, + 0.20, and + 2.83, corresponding to cool-island, mildly warming, commuter-heating, and old-city/commercial-core intensifying types. We translate these into actionable rules: along-street GVI ≥ 0.15 (target 0.20–0.35); BH ≥ 60–100 in high-mass districts to ensure continuous shading and ventilation; “open connections + continuous canopies” where IEI > 0.5; and an infill control line at BCR ≈ 0.20.
Graphical abstract