Differential Cooling Effects of Urban Parks in a Coastal City of Northern China from Maximum and Accumulative Perspectives

Abstract

As a major component of green infrastructure, urban parks can mitigate the urban heat island (UHI) significantly. However, most previous studies have only quantified the cooling effect from maximum perspective, resulting that the effect cannot be fully reflected. Therefore, in this study, park cooling area (PCA), park cooling efficiency (PCE), park cooling intensity (PCI) and park cooling gradient (PCG) were selected to quantify the cooling effect of parks from both maximum and cumulative perspectives. Fifty urban parks in Qingdao were divided into two groups: without water and containing water, correlation analysis and cluster analysis were conducted. Results show that the interior LST of each park was lower than the surrounding LST (mean Δ T = 2.36°C). Area, Perimeter, Perimeter-area ratio (P/A), Fractional vegetation cover (FVC) and Water body area ratio were significantly related to the cooling effect. It is more appropriate to control the parks without water within medium size(4-10ha) and parks containing water within large size (10-50ha). Furthermore, the impact of the surrounding environment on the park's cooling effect is enormous and sometimes can even exceed the characteristics of the park. This study could help urban planners to design reasonable urban parks according to different needs and surrounding environment.

Keywords: cooling effect, cumulative cooling indexes, urban parks, urban planning.