Methods for quantifying the cooling effect of urban green spaces using remote sensing: A comparative study

The cooling effect of urban green space (UGS) and its influencing factors have been extensively studied. However, the related results are sporadic, irregular, and even contradictory, which largely prevented the application of results to practical actions. One of the main reason may be the lack of consistency in the literature regarding the method used to quantify the cooling effect of UGS. In this study, three common methods using to quantify the cooling effect of UGS including buffer averaging method, visual interpretation method and basin analogy method were verified, compared, and evaluated. This study confirmed that different quantitative methods of measuring the cooling effect of UGS can lead to considerable differences in the results. The buffer averaging method is only applicable to conditions that the shape of UGS is regular and its surrounding landscape is homogenized, otherwise the cooling effect is easily overestimated. Visual interpretation method is the most laborious but recommended method, since it has high accuracy and can describe the directionality of cooling effect of the UGS to surrounding environment. The cooling effect quantified using basin analogy method may be uniformly overestimated or underestimated with the setting of the slope threshold, but it does not affect its accurate representation of the strength order of the cooling effect among different UGSs. The results calculated by visual interpretation method and basin analogy method are credible and highly correlated. This study emphasizes the importance of selecting and unifying quantitative method of cooling effect of UGS, which also helps to parallel compare and organize the results of relevant studies.