Anisotropic Eddy Parameterizations Implemented in a Coarse Ocean General Circulation Model

Using the results from an eddy resolving (1/12 deg.; R-grid) ocean general circulation model experiments, we explored the numerical diffusion schemes that should be implemented to the lower resolution models (eddy permitting 1/4 deg.; P-grid, and no-eddy-resolving 1 deg.; L-grid). The velocities (u, v) and tracers (T, S) are decomposed to the spatial (P-grid or L-grid) averages and the anomalies. We calculated the eddy induced transports \langle T^{'} u^{'} \rangle, \langle T^{'} v^{'} \rangle, and so on, where \langle \rangle means spatial (P-grid or L-grid) average and T^{'}=T - \langle T \rangle. We examined the dependency of the eddy induced transport on the mean quantities (e.g. \langle u \rangle, \langle v \rangle ). We estimated the diffusivity in the P-grid mean field that is explicitly represented based on the eddy tracer advection in the R-grid. It is suggested that the sub-grid-eddy parameterizations used in a P-grid model that can resolve the meso- scale eddies should be different from those in a L-grid model.