Increased wintertime European atmospheric blocking frequencies in General Circulation Models with an eddy-permitting ocean

Abstract Midlatitude atmospheric blocking events are important drivers of long-lasting extreme weather conditions at regional to continental scales. However, modern climate models consistently underestimate their frequency occurrence compared observations, casting doubt on future projections extremes. Using the prominent and largely underestimated winter in Europe as a test case, this study first introduces spatio-temporal approach activity based clustering technique, allowing assess models’ ability simulate both realistic frequencies locations events. A sensitivity analysis from an ensemble 49 simulations 24 coupled shows that presence mesoscale eddy-permitting ocean model increases realism simulated for almost all types patterns clustered observations. This finding is further explained supported by concomitant reductions well-documented biases Gulf Stream North Atlantic Current positions, well midlatitude jet stream variability.