Assessing resolution sensitivity in coupled climate simulations with AWI-CM3

Abstract. In this study, we evaluate the performance of the latest version of the Alfred Wegener Institute Climate Model, AWI-CM3, in two configurations at different resolutions, demonstrating that higher spatial resolution substantially enhances the model’s ability to reproduce key climate variables and processes. The medium-resolution configuration consistently reduces climatological biases compared to both the low-resolution setup and the CMIP6 (Coupled Model Intercomparison Project, phase 6) multi-model mean, particularly in polar regions and areas characterized by strong mesoscale dynamics. Improvements are especially notable in the simulation of sea ice variability, ocean circulation, and ocean-atmosphere interactions. The medium-resolution simulation also exhibits greater interannual variability, which may reflect a more realistic representation of underlying processes, but whose implications will need to be fully assessed with multiple ensemble members. We conclude that long-term, eddy-permitting climate projections offer promising avenues for reducing structural uncertainties in future climate projections. As global modeling efforts move toward CMIP7 and beyond, our results highlight the importance of pursuing medium-resolution strategies in parallel with improved physical parameterizations and ensemble-based evaluation to more robustly capture the nonlinearities of the Earth system.