Mitigating Climate Biases in the Midlatitude North Atlantic by Increasing Model Resolution: SST Gradients and Their Relation to Blocking and the Jet

Abstract Starting to resolve the oceanic mesoscale in climate models is a step change model fidelity. This study examines how certain obstinate biases midlatitude North Atlantic respond increasing resolution (from 1° 0.25° ocean) and such sea surface temperature (SST) affect atmosphere. Using multimodel ensemble of historical simulations run at different horizontal resolutions, it shown that severe cold SST bias central Atlantic, common many ocean models, significantly reduced with resolution. The associated time-mean meridional gradient relate positive low-level baroclinicity, while causes also static stability diabatic heating interior changes baroclinicity brought by lead improvements European blocking eddy-driven jet variability. Across clear relationship found between climatological gradients broader Gulf Stream Extension area two aspects atmospheric circulation: frequency high-latitude southern-jet regime. thought reflect two-way interaction (with feedback) respective anomalies. These anomalies are be important forcing significant responses circulation, including variability storm track. Further increases expected additional representation Euro-Atlantic climate.