Quantifying of surface urban cool island in arid environments case study: Isfahan metropolis

Abstract

The cities that are built on the arid biomes with the hot and dry climates can adjust the temperature (oasis effect) and create the urban cool island (UCI) during the day. As the background climate of the Isfahan metropolis is warm and dry, we can expect an UCI during the day. The MODIS land cover product data were used to distinguish between the urban and nonurban areas. The MODIS/Terra/LST data from 2000 to 2016 were then used for day-time view to examine the UCI. In the next step, the UCI intensity index was calculated by the spatial correlation representative pixel method for the city and the background. This study showed that due to the passage of the Zayandehrood river from the middle of the city and the expansion of vegetation in the urban environment, the metropolitan area of Isfahan is 3.5° cooler than the suburban barren lands during the day. The UCI intensity index has been intensified over the last few years and has fallen below − 4.5°. The studies have shown that the UCI intensity index is weakened during the cold months and intensified in the warm months of the year. The seasonal changes in UCI intensity in the metropolitan area of Isfahan can be related to the high variability of vegetation throughout the year.