Correlation Analysis Between Urban Green Space Morphological Indicators and Cooling Efficiency

In recent years, urban green spaces have been extensively investigated for their significant contribution to mitigating the urban heat island effect. Yet, while cooling intensity has been the dominant focus of most previous research, cooling efficiency and cooling distance remain comparatively underexplored. Based on Landsat 8 remote sensing data, an urban green space morphology-based efficiency diagnosis system was established for the built-up area of Xi'an. A total of 146 green space patches were identified, and their morphological attributes, including area, shape index, circularity, compactness, and elongation, were quantified. Patch information and land surface temperature data were jointly used to estimate cooling intensity, cooling distance, and cooling efficiency. A notably strong positive correlation emerged between cooling intensity and cooling efficiency (r = 0.84), implying that green spaces exhibiting stronger cooling performance also tend to operate more efficiently on a per-area basis. Cooling intensity was positively related to cooling distance (r = 0.33), suggesting that patches with stronger cooling effects tended to influence a larger surrounding area. In contrast, green space area showed weak correlations with cooling intensity, cooling distance, and cooling efficiency (r = -0.06, -0.10, and -0.08, respectively). The results suggest that simply increasing green space area may not lead to better cooling performance. These results provide a useful reference for green space planning in high-density cities. Where land resources are limited, improving the internal structure and connectivity of green spaces may be more effective than simply increasing patch size or creating regular-shaped green spaces.