Exploring the influence of local urban heat features on park cooling effects: Insights from Chinese cities

Urban parks are vital for mitigating urban heat, yet debate persists on whether local urban heat features hinder or enhance park cooling effects. Therefore. We employed Google Earth Engine and Landsat 8 OLI to map the average summer daytime land surface temperature (LST) across China during 2017-2019. This allowed us to evaluate park cooling effects and calculate local urban heat island intensities (LUHI) around each park. Findings revealed that: (1) urban parks had an average cooling intensity (PCI) of 1.38 degrees C, with Blue and Green Parks demonstrating superior cooling effects, particularly in arid regions. (2) Parks in hotter urban areas exhibited enhanced cooling effects, with notable PCI differences of over 0.4 degrees C among different LUHI regions, especially for Blue and Green Parks. However, this effect was not observed in the central subtropical (CST) and central temperate (CT) zones. (3) Hotter urban areas had larger Threshold Value of Efficiency (TVoE), particularly for Blue and Green Parks (0.11-0.46 ha), with CT zone parks displaying the largest TVoE among climate zones. (4) The variations in park cooling effects attributed to LUHI primarily stem from differences in land cover composition and their thermal properties. More importantly, our study underscores the greater influence of local urban heat features over urban heat characteristics on park cooling effects. Therefore, local urban heat features surrounding urban parks must be taken into account when planning urban green spaces, what's more, a larger park was more efficient in hotter urban areas.