Characterization and detection of Thermal islands in Tehran metropolis during the cold months of the year using satellite images

In some metropolises of Iran, Thermal Islands is somewhat generalization and observable. Existence of tall buildings, traffic, population density in the hub centers and especially in the central part of the city cause the creation of a Thermal island in the city. In this research, the time-spatial identification of the thermal islands of the cold season during the years 1985 to 2019 and the analysis of the factors influencing their formation were done with an emphasis on changes in land use, texture, high-rise construction, land cover and climatic variables in the Tehran city. The current research, which is based on the extraction of Landsat satellite images, produced maps of the mentioned indices using NDVI, LSE, ISA and LST indices, which became the basis of the analyses. The results of the research show that high LST values are spread in areas of Tehran where the NDVI index is relatively low and the ISA index is high. Although the formation of Thermal islands in winter is a little far from expected, small parts of the north, northwest, south and southwest of the city (zones 1, 5 and 18) are permanently exposed to Thermal islands, which are in step with dense land use and areas free of vegetation. The scattered hot spots in the mentioned areas with a temperature cover above 20 degrees Celsius in the middle of the average temperature of the city, which is lower than 17 degrees Celsius during the cold period of the year, is indicative of this fact.