Down to Submesoscale in Laboratory Experiments with Optical Altimetry

We use two-layer flows generated in a rotating tank as a model of an oceanic circulation in order to study dynamics on different scales. Large-scale circulation in our tank includes basin-scale circumpolar flow with embedded zonal jets (Fig. 1). Mesoscale meanders and eddies are created mainly by baroclinic instability due to a vertical shear, not unlike that in an ocean. Submesoscale features include thin filaments and small eddies with typical values of the Rossby number O(1). We discuss the energy spectra of the flows and the energy cascade across different scales. We also discuss the mechanisms of generation of the submesoscale eddies and their strong cyclonic preference. A question of whether it is possible to diagnose an essentially three-dimensional inertial instability by measuring the surface characteristics of eddies is investigated as well.