Assessment of Urban Geometry’s Effects on Nocturnal Urban Heat Islands Using GIS (Case Study: District of Golsar in Rasht)

Urban heat islands (UHI) is one of the most substantial phenomena related to urbanization defined by the air temperature increase of cities compared to their rural surroundings. Due to the effects of urban geometry on changing energy balance, it is considered to be one of the most important factors in the formation of UHI. One of the most important indexes of defining urban geometry is the aspect ratio parameter, which is defined by the ratio of building height to street width in urban canyons. So far, various models have been developed to simulate the intensity of UHI, and Oke's model is one of the most successful models. This model uses the aspect ratio index. Since Oke's model require descriptive and spatial analysis (especially topological analysis), the use of Geospatial Information Systems (GIS) is inevitable. This study examines the effects of urban geometry on nocturnal UHI intensity of 10 urban canyons in Golsar District of Rasht, by Oke's model and using GIS tools. The results show the canyons with higher aspect ratios intensify the nocturnal UHI, while the canyons with lower aspect ratio leads to lower UHI intensity.