Abstract
This study investigates the diurnal and seasonal variations in the effect of environmental features on air temperature in Seoul, Korea. We expect that this study will lead to the identification of factors that can be applied for urban heat island mitigation strategies in summer without leading to an unintended result in winter. As our dependent variable, we employed the smoothed 31-day moving average of air temperatures, where we controlled the seasonal variation by normalizing the values observed from 247 automatic weather stations (AWS) from 2015 to 2016. Subsequently, we conducted consecutive log–log regression analyses of each day to examine patterns of change in regression coefficients and the significance of each independent variable. For independent variables, we applied built environment features including albedo, land-use, average building floors, the sky view factor, and green and water areas. This study provides analytical results regarding the relationship between environmental factors and air temperature. This study also addresses imperative issues for planners, especially regarding albedo, wind path, building geometry, and land use types. Finally, this study gives useful insights for managing the diurnal and seasonal variations of urban thermal environment in the mega-city.
Highlights
In recent decades, the urban heat island (UHI) effect has been among the most well-documented effects of urbanization along with climate change [1]
Our results showed that larger traffic road area is associated with higher air temperature throughout all seasons except for winter daytime
We suggest that planners and policymakers, especially those from urban areas that have both hot and cold seasons, should be aware that altering the albedo to mitigate air temperature may lead to unwanted outcomes
Summary
The urban heat island (UHI) effect has been among the most well-documented effects of urbanization along with climate change [1]. While there are no strict definitions of UHI, it is generally defined as a phenomenon in which the temperature difference between the city center and its suburbs is positive [2,3,4]. The UHI effect has been viewed as a severe threat to populations since high temperatures and heat waves may cause an increase in heat-related mortality [5]. Seoul, the capital of South Korea, the number of heat-related illness reports has increased on average. From 2011 to 2015, 287 cases of heat-related illness were reported, an average of 57.4 per year. This increased to 170 in 2016, according to the Korea Centers for Disease Control and Prevention
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