Mapping urban cool air connectivity in a megacity

Abstract

Urban heat islands and global warming negatively impact human health, and it is important to analyze the effects of urban cool islands (UCIs). Previous studies have used land surface temperature to define the effect of UCIs, but they have difficulty representing the spread of cool air. Here, we suggest a new method for mapping the UCI effect using a landscape connectivity model. We combined the urban heat flux to simulate the cooling potential and surface roughness to represent resistance to cool air spread from UCIs across 605 km2 of Seoul, Republic of Korea. The results identify high cool air connectivity areas in the Han River, which bisects Seoul, and along ridges that provide a cooling potential of approximately 440 W/m2. Areas with low cool air connectivity have a high frontal area index, which blocks cool air flow. The mapped cool air connectivity results have a − 0.56 correlation coefficient with monitored air temperatures, which shows that our result can be used to identify the UCIs network and to optimize the best areas for new UCIs. This research method can be utilized to plan cooling strategies for cities with few air-temperature monitoring stations.