| Popis: |
Midlatitude atmospheric blockings are important drivers of long-lasting extreme weather conditions at regional to continental scales. However, modern climate models consistently underestimate their frequency of occurrence compared to observations, casting doubt on future projections of climate extremes. Using the prominent and largely underestimated winter blockings in Europe as a test case, this study first introduces a spatio-temporal approach to study blocking activity based on a clustering technique, allowing to assess models' ability to simulate both realistic frequencies and locations of blockings. A sensitivity analysis from an ensemble of 22 coupled climate models shows that the presence of a mesoscale eddy-permitting ocean model increases the realism of simulated blockings for almost all types of patterns clustered from observations. This finding is further explained and supported by concomitant reductions in well-documented biases of large-scale atmospheric and oceanic features, namely Gulf Stream and North Atlantic Current positions and the midlatitude jet stream variability. |
