An Analysis on Diurnal Actions of the Urban Heat Island of Tehran



The urban heat island effect refers to the temperature rise of the cities in comparison to the suburbs. This phenomenon which is a consequence of urbanization and has become a major issue in the urban climatology may have serious consequences in the developing countries which are facing a rapid and unplanned urban growth. Tehran, the capital and the most populated city of Iran, this phenomenon is obviously seen due to various factors. In this study, in order to analyze the diurnal actions of the urban heat island formation 8 days of the year 2006 were studied using an integrated method. The meteorology data were gathered from 14 surface stations and the wind field was simulated using The Air Pollution Model (TAPM). The spatial formation of the heat island was calculated using ArcGIS 9.3 with a 3 hours interval. Statistical calculations including the heat island intensity was done using MS Excel. The results show that despite reaching the threshold wind velocity, the heat island intensity has always been positive. Besides, wind direction and speed plays the most significant role in the formation of the heat island. And, there is no direct relation between the air pressure and the heat island. The main core of the hat island of Tehran is located between the Stations of Bahman, Bazaar and Azadi and the main cold core is located around the stations Tajrish, Shomal e Tehran and Aghdasyeh.