Analysis of Hotspot Changes in Daegu Metropolitan City in Summer Using Landsat 8 Satellite Images

Increasing temperature due to climate change and the urban heat island effect caused by rapid urbanization can deteriorate the thermal environment in urban areas, leading to negative impacts such as increased heat stress during summer and higher energy consumption.In particular, basin topography is considered an ideal area for studying changes in the thermal environment, as its structure hinders the escape of heat from the city, making these issues more pronounced.In this study, a thermal environment based on the hotspot in the summer of Daegu Metropolitan City, a representative basin topography, from 2013 to 2023 was analyzed using Landsat 8 Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS) satellite images.The land surface temperature (LST) was calculated from the thermal infrared band of the satellite image and LST was normalized between 0 and 1 in consideration of outliers and clouds.Hotspot change analysis was performed by calculating the ratio of hotspots to the total area for the entire year.Results showed an increase in hotspot areas compared to previous years, with larger expansions observed in years with severe heatwaves.Subsequently, Moran's I and Local Indicator of Spatial Association (LISA) analysis were used to confirm clustering patterns within the thermal environment.This study identifies hotspot variations due to summer heatwaves, and this thermal environment analysis is anticipated to contribute to policies aimed at improving the urban thermal environment.