Spatial variations of intra-city urban heat island in megacity Delhi

This study examines the variation of intra-city Urban Heat Island (UHI) in megacity Delhi by the mobile transverse measurement technique and spatial maps of UHI along the mobile routes have been generated for the city by using the ordinary kriging interpolation tool of ArcGIS. Meteorological data was collected by mobile surveys under clear sky weather days in monsoon and winter months of 2014 using two HOBO data loggers installed on a vehicle along the routes which covered many parts of Delhi intersecting vertical and horizontal transects capturing different land use patterns of the city. UHI values obtained through interpolation were validated with UHI obtained from temperature measurements at five fixed sites spread over the Delhi region, which were found in good agreement (R2 = 0.91). The variability existing in the two seasons studied has been shown by low UHI values obtained in the monsoon season and high UHI values in winter season. The diurnal pattern of UHI showed higher UHI during the nighttime period, compared to morning and noon periods. The results show variable UHI in different regions of Delhi covered by mobile routes with high UHI values of >6 °C observed during the winter period.