Examination of the urban heat island effect using the local climate zones classification system: The case of Ankara city center

With the increasing population, the climate changes significantly in the cities that expand horizontally and rise vertically. Brought along by the urbanization, the increase in temperature in the city centers due to the high construction, increase in impermeable surfaces, high heat holding capacity of the used materials has increased the tendency towards urban climate issues. Climate change and urban heat island formation in urban areas are a common phenomenon for every city and a common result of urbanization. For this reason, studies are carried out with many different methods for different cities in the world. The "Local Climate Zones Classification Scheme" developed by Oke and Stewart is designed to standardize climatic observations. The spatial expansion took place very quickly in various planning periods of Ankara, which has always been a growing city with a population increase above the predictions since the process that started with becoming the capital. The heat island effect that occurred in the city of Ankara because of rapid urbanization has been the subject of different studies. Within the scope of the study, the heat island effect in the city of Ankara has been revealed by using the local climate zone classification system, which is a new and different approach to urban heat islands. In this context; eight local climatic zones (LCZ-2, LCZ -3, LCZ -4, LCZ-5, LCZ-7, LCZ-8, LCZ-A, LCZ-E) out of 17 local climatic zones in the area of the study was determined and the relationship between the surface temperatures and the built environment was analyzed. According to the analyzes made, the local climate region with the lowest average surface temperature; LCZ-A (woody areas; Altınpark, Genç park, Gültepe cemetery) and its average temperature is 36.7°C. The local climate region with the highest average surface temperature is LCZ-3, where low-rise dense construction is observed, and its average temperature was measured as 40.0°C. As a result of the analyzes made to reveal whether there is a significant relationship between the characteristics of the built environment of the city and the density of the urban heat island, it has been statistically demonstrated that there is a significant relationship between the building surface area and building height, albedo, heat flux, ndvı, sky view factor and impermeable surface measurements; and these properties explain 52% of the surface temperature. In addition, a significant relationship was found with the aspect and height of the urban natural environment characteristics.