The Impact of Urban Green Spaces on Wet-Bulb Temperature at the Neighborhood Scale in Shunde

doi:10.3969/j.issn.1007-6190.2025.04.015

Abstract：To investigate the spatiotemporal distribution characteristics of temperature and humidity and wet-bulb temperature in a typical city of the subtropical monsoon humid climate zone, which is a high incidence area of heat stress, this study uses satellite remote sensing-derived normalized vegetation index to take Shunde District as an example. It clarifies the comprehensive effect of urban green spaces on wet-bulb temperature during summer heat waves, thereby comprehensively evaluating the effectiveness of urban green spaces in alleviating urban heat stress. The results show that: (1) Compared with non-green space sections, during heat waves, urban green spaces in Shunde can significantly reduce temperatures during the day, but green space sections are more likely to experience high values of wet-bulb temperature in the afternoon. At night, the effect of urban green spaces in reducing wet-bulb temperature is very significant, and high values of wet-bulb temperature basically do not occur. (2) When the temperature in the morning is below a certain threshold, the cooling effect is sufficient to offset the increase in wet-bulb temperature caused by local vapor pressure. However, when the temperature exceeds a certain threshold, the humidifying effect of green spaces becomes dominant, and the cooling effect of green spaces is insufficient to offset the increase in wet-bulb temperature caused by local vapor pressure. (3) In urban planning, more attention should be paid to the distribution of tall-canopied trees that are relatively sparse, avoiding excessive vegetation coverage leading to excessively high local vapor pressure in the afternoon, thus causing high wet-bulb temperature and exacerbating the heat stress of urban residents.