Simulations of internal-wave breaking and wave-packet propagation in the thermocline

An investigation into density and velocity fluctuations in the oceanic thermocline is presented. Two kinds of numerical simulation are reported. In the first, an attempt is made to capture the transition from breaking internal waves to the small-scale turbulence they generate. The model used for this is based on a continual forcing of a large-scale standing internal-wave. Evidence is presented for a transition in the energy spectra from the anisotropic k buoyancy range to the small-scale k isotropic inertial range. Density structures that form during wave breaking are analyzed and regions of mixing associated with the breaking events are visualized. In the second kind of simulation, internal-wave packets are followed as they propagate through the thermocline. It is found that the breaking of crests within the packet can lead to overturning events on the scale observed in the ocean, and the subsequent turbulence can form a continuous wake.