Long-term impact of urban areas on meteorological conditions over Central Europe

The impact of urban areas on relevant meteorological variables, especially on temperature and wind speed, is well-known, and several studies have evaluated this effect. However, fewer of them have focused on the impact of urban areas on cloud cover and precipitation. In this study, a total of 15 simulations were performed using the Weather Research and Forecasting (WRF) model on a Central European domain at 9 km horizontal resolution for 10 years. Results were compared to a selection of ECAD station data distinguishing between urban areas and their rural counterparts for six different Central European cities. Changes in temperature and specific humidity are mostly sensitive to the urban scheme selected, while changes in precipitation and cloud cover are more sensitive to the parameterization of convection and microphysics. Despite differences observed between cities, cloud cover increases over urban areas during the afternoon and evening and decreases during the morning and night, especially in summer. Precipitation in winter does not show a significant variation between simulations. On the other hand, precipitation is enhanced over urban areas during summertime. This study highlights the importance of using model ensembles and a number of cities when evaluating the urban heat island (UHI) and urban meteorology island (UMI) meteorological values, as large differences exist between the different setups and the selected cities.