Internal-Wave-Packet Propagation and Breaking

Abstract

Packets of internal waves propagating vertically through the ocean can locally overturn the fluid producing turbulence and mixing. In order to explore this phenomena, two kinds of numerical simulations are performed. In the first, internal-wave packets are followed as they propagate. It is found that the breaking of wave 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. In the second kind of simulation, an attempt is made to capture the transition from breaking internal waves to the small-scale turbulence they generate. Evidence is presented for a transition in the energy spectra from the anisotropic k(-3) buoyancy range to the small-scale k(-5/3) isotropic inertial range. Density structures that form during wave breaking are analyzed and regions of mixing associated with the breaking events are visualized.