The interaction between urban heat island and urban parks: An in-situ measurement-based review

This study is a comprehensive review examining the role of urban parks in mitigating the urban heat island (UHI) effect and enhancing outdoor thermal comfort (OTC) based on in-situ measurements. The review analyzed 48 articles based on criteria such as park size, parks' location using the Köppen-Geiger Climate Classification, number of measuring points, the presence of an OTC index, and public survey data, including participant numbers when available. This review categorized urban parks into five fundamental approaches: (1) the heat-mitigating and other climatic effects of urban parks, (2) the cooling effect spreading from parks into the city, (3) the thermal roles of vegetation in urban parks, (4) effect of the spatial configuration near parks on the urban microclimate, and (5) the thermo-psychological perception and behavior of people in urban parks. The results indicated that larger parks had a more significant cooling effect. A 3.4-ha park lowered the temperature by 0.5 °C, extending the cooling effect to 391 m. A 125-ha park reduced the air temperature by 1.6 °C at 130 m and by 0.9 °C at 280 m. A 680-ha park extended the cooling effect up to 1 km, with temperatures ranging from 0.6 °C to 2.8 °C. A common characteristic of these parks is their high tree density and canopy ratio, which appear crucial in fostering cool microclimate conditions. In addition to environmental factors, users' demographic characteristics and personal perceptions significantly influence OTC. This study offers a novel approach for planners and decision-makers, helping them identify critical areas for urban park development and align local ecosystem preservation efforts and urban planning priorities to protect communities from climate risks such as UHI effectively.