Tempo-spatial behavior of Surface Urban Heat Island of Isfahan Metropolitan Area

Abstract

The population of Isfahan has increased ten times over the past six decades. The rapid urbanization of the historical city of Isfahan has had a great environmental impact. At the same time, drying of Zayandeh Rood, increasing the air temperature, decreasing rain has brought the city to a critical environmental situation. The emergence of the urban heat island is only one of the consequences of the environmental changes of the past decades. Urban heat island has consequences for the health of citizens and it affects the consumption of water and energy. In this study, MODIS Aqua/LST data was used for night and day from 1379 to 1395. By using this data, the background climate of the metropolis of Isfahan was identified with the distance-azimuth (DA) charts. Then the representative pixel within the city and the representative pixel of the background climate were identified. Based on the time series of LST over these two pixels SUHI index of Isfahan metropolis was calculated. Studies show that the Isfahan metropolitan area is colder than the suburbs during the day and it is warmer than its surroundings during the night. The magnitude of the SUHI is maximal in January and is weaker in the summer. Regarding the temporal and spatial behavior of the SUHI, it seems that the changes made by the city in humidity, albedo, and composition of the atmosphere have played an important role in the emergence of the SUHI. Zayandeh Rood has played a major role in modulating the land surface temperature in the metropolitan area of Isfahan, and its drying has had environmental consequences