Improved Simulation of Midlatitude Climate in a New Channel Model Compared to Contemporary Global Climate Models

A midlatitude channel model (MCM), zonally global but meridionally bounded, is constructed for the Northern Hemisphere (0°–360°, 26°N–60°N), based on the Weather Research and Forecasting model. The MCM simulates the midlatitude at a higher resolution than typically possible in a global climate model (GCM). On the other hand, compared to four lateral boundaries in a standard regional or limited-area model, MCM is bounded on two meridional sides only allowing the simulated atmosphere to develop more freely. Based on a 4-year simulation at ∼0.33° horizontal grid-spacing, the MCM realistically captures the annual mean and seasonal cycle of the midlatitude atmosphere and the meridional heat transport by the stationary and transient eddies that dominate the winter weather. Moreover, a comparison of MCM with the ensemble mean of 20 contemporary atmospheric GCMs reveals that the MCM performs better than the GCM ensemble mean. Possible applications of this new modeling configuration are discussed.