Abstract: The urban heat island effect seriously affects daily life and health of urban residents. Urban green space is an effective way to alleviate urban heat island effect and reduce urban surface temperature in summer. We selected the main urban areas of Tianshui, Xi’an, and Yuncheng (the three cities belong to the Guanzhong Plain urban agglomeration) as the research areas. Based on the MODIS, Landsat 8 and Sentinel-2 data from July to August 2021, the land surface temperature was inverted, and the green space information was extracted. Using GIS spatial analysis, landscape ecology and statistical analysis methods, we examined the impacts of green space patch area, shape characteristics and landscape pattern index on cooling effect. The results showed that under different urbanization levels and scales, green space patches had a stable cooling effect. With the increases of urbanization level, the cooling effect of same green space patches was enhanced. Compared with the scattered small-area green space with complex shapes, the large-area green space with continuous concentration and regular shape had a better cooling effect. When the green space area reached 10 hm² or the area/perimeter ratio increased to 3, the enhancement range of cooling effect decreased as the green space area increased and the shape became regular. Our results provide a scientific basis for green space planning in areas with different urbanization levels.

Key words: urban heat island, green patch, cooling effect, landscape pattern.