Assessment of monthly variations of Urban Heat Island in Delhi using Landsat 8 dataset

Urban Heat Island (UHI) effect is a multi-scaled phenomenon, i.e., it may occur within a city in different sizes, shapes, intensity and time. As a climatic event, UHI acquires characteristic variations at different temporal scales. In this study, the temporal and spatial variability of the Surface UHI (SUHI) over Delhi was examined for different temporal scales, based on remotely sensed data and thermal data collected during a time frame of 1-year, i.e., from June 2017 to June 2018. During the last few decades, Delhi has experienced unparalleled horizontal and vertical growth, leading to major modifications of land use/cover. Land Surface Temperature (LST) datasets of Delhi were generated from Landsat 8 OLI/TIRS imagery. LST data, thus, obtained was compared with rural reference data and analysed with respect to the thermal field data. Using these LST maps, average SUHI intensity over Delhi was calculated to be 3.86 degrees C for the whole year. The calculated SUHII showed high values in summer during the day than in winter. The relationship between LST and NDVI for each month was also assessed, which showed strong negative correlation with an average r value of -0.45. Furthermore, the Central Delhi Region and commercial areas displayed heat island conditions almost throughout the year. The results of this study suggest that the monthly variations of SUHI of Delhi are related with the climatic background, local meteorological conditions, and surface characteristics.