Urbanization-induced changes in convective and frontal precipitation events in Ankara

Abstract

Urbanization has been demonstrated to alter precipitation characteristics. However, there is a lack of modeling-based examination of the interaction between urbanization and precipitation in Turkey. Here, we analyze the urban impacts on two precipitation events with different synoptic backgrounds in Ankara using the Weather Research and Forecasting model. The rainfall occurrences were selected considering the urban heat island (UHI) intensity over the urbanized area. We conceptualize urban and nourban configurations using the CORINE land cover data and create ensemble simulations. Our findings underline the dissimilarity in the urban impacts on the precipitation pattern of the selected events. The urban scenario suppressed the rainfall over the downwind and upwind of the urban center by more than 10 mm for the summertime event, reshaping the rainfall pattern to be more spatially distributed and protracting the rainfall duration. By contrast, the urban impact on the springtime event is less discernible, with less than 1% change in the rainfall amounts over the urban center. Strong synoptic forcing and significantly less UHI magnitude for the springtime event are responsible for the masked urban impacts on precipitation. Regardless, the urban land use changed the surface energy balance, reducing the moisture content over the highly urbanized area.