Field effect and coupling influences of urban park cold islands under varying wind speeds and heat island gradients

Abstract

Urban parks effectively mitigated the urban heat island (UHI) effects. The field extent and boundary of cold island effects, influenced by internal landscape characteristics of parks, external urban morphology and regional climatic factors, determined cooling service magnitude. The study used buffer analysis to calculate the park's cold island effect, introduced fundamental concepts and delineation methodologies of the cold island rose and cold island effect field. Ultimately, the study explored the coupling relationship between the park's cold island effect and its internal landscape, external urban morphology, across various wind speeds and heat island gradients. It was found that the parks located in the warmer zone of the urban heat island gradient showed greater maximal cooling distances (L_MAX) and intensities (CPCI). L_MAX and CPCI were more influenced by internal landscape metrics than external urban morphological metrics. The 3–4 m/s of wind speed was a threshold discriminating the effects of wind speed on cold island effects. Below this threshold, greater L_MAX and CPCI were shown for the upwind area; exceed, downwind area did. UHI could be alleviated by utilizing the internal landscape features of the park, arranging the external urban form, and increasing urban ventilation corridors based on urban wind and thermal conditions.