Using station-pair to elucidate the cooling effect of vegetation in megacities

The air urban heat island (UHI) poses significant challenges to urban environments. While vegetation is a recognized mitigation strategy, the in-situ cooling effects of different vegetation types, such as forests and grasslands, across diverse climatic regions remain poorly quantified. This study addresses this gap using a station-pair regression approach to evaluate vegetation's cooling efficacy in three major Chinese cities: Beijing, Shanghai, and the Mega-city Cluster in the Pearl River Delta (MCPRD). We developed multiple linear regression models using summer data from 2016 to 2020. These models predict the air temperature difference between paired meteorological sites based on spatial differences in vegetation conditions, derived from high-resolution Sentinel-2 imagery, distance to large water body, wind speed, and elevation. The model performed well, achieving coefficient of determination of 0.71, 0.58 and 0.82 for Beijing, Shanghai and MCPRD, respectively. Crucially, our results show that compared to completely urbanized land, existing vegetation significantly lowers air temperature by 2.43 °C in Beijing, 0.58 °C in Shanghai, and 2.74 °C in the MCPRD. This research quantifies the variable cooling benefits of urban vegetation across different climate zones, providing an empirical basis for optimizing green infrastructure in urban planning to enhance thermal comfort.