Impact of eddy-rich ocean resolutions in the representation of midlatitude storm in global climate models

The physical processes affecting cyclogenesis and intensfication of midlatitude storms often occur at scales smaller than those resolved by the global climate models, which has previously restricted their use for present and future storm climatology assessments. The Process-based Climate simulation: Advances in high resolution modelling and European climate risk assessment (PRIMAVERA) and the associated CMIP6 High Resolution Model Intercomparison Project (HighResMIP; Haarsma et al. 2016) has highlighted the need for global storm-resolving climate models, with significant improvements seen in the frequency, intensity and structure of mid-latitude storms by increasing resolutions from 100 km to 25 km. The European Eddy-Rich Earth-System Models (EERIE) offer the highest available resolutions (~10 km) that explicitly resolve ocean mesoscale features, furthering our understanding of their impacts on the large-scale circulation, including storm-tracks and jet streams. In this study, we evaluate the historical (1950-2014) simulations from the four coupled EERIE models in their representation of mid-latitude storms and their effects on the eddy-driven circulation. We also present results from the sensitivity experiments (atmosphere-only), which are designed to isolate the impact of ocean-mesoscale eddies on the large-scale circulation. We find that the impact of ocean mesoscale eddies on the climatological storm track remain small, which is expected as the flux-enhancing effect of eddies is largely overwhelmed by the the strong meridional temperature gradients associated with fronts.