Climatology of Urban Heat/cold Island of Metropolises of Iran

Urban development and industrial activities have led to dramatic changes in the physical characteristics of the land surface, energy balance and, as a result, local climate change in big cities. To investigate heat/cold island intensity, Modis Terra and Aqua data were used to obtain land surface temperature from 2002 to 2016 and all cities with a population of more than 500,000 were selected. Modis land cover data were used to extract urban and non-urban areas. And so the difference between the maximum and minimum latitude and longitude of the urban area was obtained and on every side, the city was expanded to its size To specify the non-urban area. In the next step, a representative temperature of the non-urban had to be selected from non-urban cells. For this purpose, for each day the temperature that had the highest frequency among all cells of the non-urban was selected as the representative temperature of the non-urban. And the urban heat/cold island intensity was obtained from the difference between the Representative temperature of non-urban and all urban cells. The result shows that at the day in all metropolises except Rasht from a cold island. At night, except Zahedan, which has a weak cold island, in the other city form a heat island.