Kilometer-scale simulation of atmospheric in-cloud ground icing over complex terrain in Norwegian Arctic

This study investigates in-cloud ground icing over Fagernesfjellet, a complex terrain site in northern Norway, using new kilometer-scale simulations from the Weather Research and Forecasting model (WRF) during the year 2022–2023. The WRF-derived icing results and meteorological parameters relevant to in-cloud icing are validated using measurement data (MEAS), with focus on model resolution and terrain height. Our findings indicate that WRF effectively represented the temporal evolution of icing events, with higher altitudes indicating more severe icing and an increased number of annual icing hours. However, in the current model setup, WRF underestimates the magnitude and variability of icing loads; an improvement in icing load amount is found when accurate terrain height point is used. The highest spatial resolution improved the simulation of key meteorological parameters, such as temperature and wind speed, but struggled with relative humidity and wind direction. Our study shows that high-resolution simulation and accurate terrain height are essential for improving atmospheric in-cloud ground icing simulations over complex terrain. • We report the first validation of high-resolution (1 km) WRF-simulated icing loads and meteorological variables over Fagernesfjellet, a complex terrain site in the Norwegian Arctic, based on 2022–2023 measurements. • A simplified model to compare measured icing load against WRF simulations. • Importance of high-resolution modelling for accurate atmospheric icing estimation. • Altitude-dependent icing assessment to improve icing predictions across different altitudes.