International Symposium on Stratified Flows

High values of lateral diffusivity, O(1) m²s⁻¹, on horizontal scales of 0.1-10 km are routinely found in the stratified ocean interior, irrespective of ambient mesoscale strain rate, yet the primary dynamical mechanism responsible for this behavior has not been established. Theoretical arguments combined with numerical simulations using both a nonlinear Boussinesq model and a linear internal wave model suggest that Stokes drift driven by a weakly nonlinear Garrett-Munk internal wave field can significantly enhance lateral diffusivity. In this note, we illustrate the dispersive role of internal-wave-driven Stokes drift for several stratification profiles and positions in the water column and also consider scale-dependent dispersion in submesoscale fields that include both vortices and internal waves.