Outlier detection of land surface temperature: Kucukcekmece Region

Abstract

Unplanned and rapid urbanization is one of the reasons for the rising surface temperature in urban areas. There is a large amount of literature demonstrating the association of urbanization with surface temperatures. Kucukcekmece Lake, an important lake that has been meeting the utility water needs of Istanbul, and the unplanned and rapid urbanization around it, has been affected by this inevitable change for years. Although surface temperatures generally correlate strongly with each other, very high and very low temperature values should not be disregarded and need to be investigated. The current study was conducted with the assumption that these values could be outliers; thus, they were analyzed using the box plot method for the selected region. Correlations between land surface temperature (LST) values obtained for Kucukcekmece and its vicinity were examined using Landsat Operational Land Imager (OLI) images from June 20, 2016 and June 23, 2017, and LST outliers and regions with common outliers on both days were determined. In the study, 310 LST outliers were identified for June 20, 2016 and 34 LST outliers for June 23, 2017; in both images, 33 outliers were found to be common and these clustered in two different buildings. The reasons for the outliers outside the standard surface temperature values as well as the recommended solutions were discussed.