Spatio-temporal Variation of the Daytime Surface Temperature in Local Climate Zones, Forming Cool Island in Bhopal.

Natural and man-made changes in the environment cause surface heating or cooling in the metropolitan areas in comparison with the rural areas. The urban area and surrounding rural areas have differences in energy balance due to variations in surface characteristics. These differences in temperature are the main reason for the formation of Urban Heat Islands or Urban Cool Islands. This research explores the spatio-temporal variations in surface temperatures during the daytime in Bhopal city—a case of the fast-developing metropolitan city having a composite climate. To explore the surface cool island phenomena, this research built a temporal and spatial difference in Local Climate Zones (LCZ) with Land Surface Temperature (LST) and Spatial indices. Remotely sensed Satellite data—Landsat-5 and Landsat-8, from 1990 to 1995 and 2015 to 2020, were acquired to investigate the LST and generate the LCZs. Both pre-monsoon and post-monsoon period data were analysed. LCZ was classified on the basis of built-up area, vegetation, and agricultural areas of Bhopal. The LCZ classes were analysed with LST, and LST was further correlated with vegetation and moisture indices using Pearson's correlation. Different indices are investigated in order to determine the major causes of observed LST patterns in different LCZ. A linear negative correlation was found between NDVI and LST up to − 0.4 at 0.01 significance. The statistical association between NDBI and LST has shown a positive correlation across the seasons, indicating that impervious surfaces result in high surface temperatures. The LST of water surfaces, i.e. LCZ G is 3 ^°C to 5 ^°C lower than that of other LCZ classes. The moisture Index (NDMI) and LST have a negative correlation of −0.55 that was greater and more consistent. The result from 1990 to 2020 shows that the LST of LCZ in rural areas of Bhopal is almost 2.5 ^°C to 3 ^°C higher than the urban area LCZs. The above spatio-temporal analysis of LST thus confirms the formation of Surface Urban Cool Island in the Bhopal urban area during day time and has a comparatively low surface temperature as compared to its surroundings. [ABSTRACT FROM AUTHOR]