An eddy-permitting model of the Mediterranean Sea with a two-way grid refinement at the Strait of Gibraltar

An eddy-permitting model of 18° resolution is implemented covering the whole Mediterranean Sea. Within this grid a 124° resolution model of the Strait of Gibraltar is embedded. The two grids belong to different models that are coupled through an external parallel driver. The robustness of the adopted grid refinement procedure is tested on a multi-decadal integration simulating the present climate. The good agreement found between the model circulation and most of the available observations confirms both the robustness and effectiveness of the two-way grid refinement technique. The effects produced on the Mediterranean circulation by the grid refinement are investigated through the comparison of two simulations differing only in the presence of the grid refinement. Even though the main characteristics of the thermohaline circulation appear similar in the two simulations, some quantitative and qualitative differences are observed: the main differences found in the Strait of Gibraltar propagate into the whole basin, have an impact on the water column stratification, and consequently on the convection events.