SOMAR-LES for multiscale modeling of internal tide generation

A novel modeling technique is developed to study baroclinic energy conversion when the barotropic tide oscillates over underwater topography. In SOMAR-LES, a Large Eddy Simulation (LES) model that resolves turbulence scales is coupled with a large-scale model, Stratified Ocean Model with Adaptive Refinement (SOMAR). Thus, we overcome the constraints posed by the wide range of temporal and spatial scales during tide and topographic interaction. Two-way coupling is developed: LES is driven with large scale forcing, and SOMAR receives feedback in the form of eddy viscosity and diffusivity. Numerical simulations are performed with SOMAR-LES for supercritical and subcritical ridges with ridge length scales of $ \mathcal{O}$(10 km) and barotropic forcing that corresponds to the regime of low outer excursion number, $Ex = U_0/\omega l \simeq 0.1$. Results from the coupled model are compared against ongoing high-resolution LES to ascertain the accuracy of this technique. The simulation data is analyzed to quantify baroclinic energy conversion and the change in modal composition from near to far field.