부산 도시 열섬과 열대야의 상호작용 분석

Abstract

Urban heat islands (UHIs) can intensify during high-temperature weather events such as tropical nights, leading to even greater thermal stress in cities. This study investigates the interactions between UHIs and tropical nights in Busan, South Korea, using 52 years (1973~ 2024) of observational data. In Busan, the frequency and intensity of tropical nights are 48.8% and 0.19oC higher than in rural areas, respectively, and these differences have become more pronounced as urbanization has progressed. On average, the UHI intensity is higher on tropical nights than on non-tropical nights, as warmer, drier, and less cloudy nighttime conditions on Busan’s tropical nights lead to a positive interaction between UHIs and tropical nights. However, the UHI-tropical night interaction shows considerable variability, being either strongly positive or strongly negative. This is caused by contrasting characteristics of tropical nights in Busan, which result from their different mechanisms and synoptic patterns. Specifically, tropical nights that exhibit strong positive interactions with UHI are relatively calm, dry, and hot with clear skies, driven by strong insolation and subsidence under the dominance of a persistent anticyclone. In contrast, tropical nights that exhibit strong negative interactions with UHI are much more windy, cloudy, and moist. They are driven by reduced nighttime radiative cooling and warm advection when warm moist air is transported by southwesterlies at the periphery of the western North Pacific subtropical high.