ROMS effective resolution

The increase of model resolution naturally leads to the representation of a wider energy spectrum. As a result, in recent years, the understanding of oceanic submesoscale dynamics has significantly improved. Also, the ubiquity of upper ocean frontal dynamics driving a direct energy cascade is now acknowledged. In the forward cascade framework, numerical and physical closure are more consistent in principle, but dissipation in submesoscale models remains dominated by numerical constraints rather than physical ones. Thus, the model’s effective resolution can be defined by its numerical dissipation range, which is a function of the model numerical filters (assuming that dispersive numerical modes are efficiently removed). Using a multi-nested numerical study of tropical instability waves, we will show that the spectral expression of numerical dissipation can be rather complex and extend further than normally expected. These results will provide a basis for reviewing the current state and development prospects for the AGRIF version of ROMS and introduce a new model intercomparison project called COMODO.