Exploring Urban Heat Islands with a simple thermodynamic model

The Urban Heat Island (UHI) effect, where urban areas experience higher temperatures than surrounding rural regions, presents a significant challenge in urban climatology due to global warming and rapid urbanization. This study investigated the fundamental mechanisms of UHI by combining theoretical modeling with observational data from South Korea, focusing on urban heat storage, anthropogenic heat, and climatic factors. Using a simple day-night model based on the Surface Energy Flux Balance (SEFB) framework, we demonstrated that UHI primarily results from two mechanisms: reduced diurnal temperature range (DTR) due to high heat capacity of urban materials, and increased mean temperature from additional energy fluxes like anthropogenic heat. These findings emphasize stronger UHI intensity during nighttime compared to daytime. Validation using observational data showed qualitative agreement between theoretical predictions and actual phenomena. Comparison between Seoul (urban) and Boeun (rural) revealed higher nighttime temperatures in Seoul despite its higher latitude, highlighting the role of urban heat storage. Analysis of metropolitan and new cities showed strengthening UHI effects with population growth, consistent with model predictions of decreased DTR and increased mean temperature. This research provides foundational data for understanding urbanization's impact on climate change and sustainable urban planning.