Monitoring the Urban heat islands with a Fractal Net Evolution (FNEA) Approach (Case Study: Tehran Metropolis)

Urban heat islands is the result of urban Climate and one of the important environmental challenges in the 21st century. The aim of this research is to evaluate the combined effects of biophysical components and Land surface temperature with a special Fractal Net Evolution (FNEA) in order to extract the urban heat islands in Tehran. In the first stage, Landsat 8 satellite TIRS 3 images for August, 2013, 2015, and 2015 were calculated for land surface temperature (LST) and the urban heat islands were extracted by adopting a special Fractal Net Evolution (FNEA) Approach. In order to evaluate the role of biophysical components in the formation of urban thermal islands, BI, MNDWI, NDBI, NDVI, SAVI and UI indices were calculated and evaluated. The results showed that there is a negative linear correlation between vegetation and urban heat islands. Also, a strong positive relationship was found between the impenetrable surfaces with urban heat islands in Tehran metropolis. The UHIs of Tehran metropolis with FNEA approach was classified into five categories: cold UHIs, cold second UHIs, medium UHIs, second-order thermal UHIs and warm UHIs, with an average of 95 km2 hot warm islands and 73 km² of the total urban heat islands Tehran metropolis. The most important identified UHIs are also in the 1- zone 21 due to the intense focus of most factories, industrial workshops and warehouses; 2- Zone 9 due to the location of Mehrabad airport, terminals of passenger transportation and main access passage; 3- Zone 22 and North Zone 19 is located because of the focus of Barren land and 4- Zone 13 (uncovered land around the former Dashan Tape airport) and the southern regions of Tehran (due to the existence of educational and industrial workshops).