Are the Largest Benefits of Kilometer‐Scale Climate Models Over Mountains or Over Flatland?

Abstract Climate and weather simulations are challenging in mountainous regions, due to complex meteorological processes. While a kilometer‐scale grid spacing significantly improves the representation of topography, little is known about the associated added value over mountains. Here we evaluate various kilometer‐scale climate simulations against observations of precipitation, temperature and cloud cover over Europe, distinguishing high versus low mountains and flatland. We show that the increase in the resolution generally improves model performance, but depending on the model this added value can be larger, smaller or even absent over complex mountainous terrain. Using several models and configurations, we identify the choice of parameterizations as a possible important factor controlling mesoscale influences on mountain climate. These results suggest that the full potential of kilometer‐scale simulations in regions of complex topography may not be reached yet, and call for future research to improve the remaining parameterizations like turbulence.