Idealized Solutions for the Energy Balance of the Finescale Internal Wave Field

Abstract

Recent fine- and microstructure observations indicate enhanced finescale shear and strain in conjunction with bottom-intensified turbulent dissipation above rough bathymetry in the Brazil Basin. Such observations implicate the bottom boundary as an energy source for the finescale internal wave field. Simple analytical and numerical solutions to an equation governing the spatial and temporal evolution of the finescale wave field are described here. The governing equation implicitly treats the effects of wave breaking on the vertical propagation of internal waves through a flux representation of nonlinear transports associated with internal wave?wave interactions. These solutions identify the rate of dissipation of turbulent kinetic energy with downscale energy transports at high vertical wavenumber, resulting in an estimate of dissipation versus depth. The sensitivity of the turbulent dissipation depth profile to various environmental parameters is examined. Observed dissipation profiles and shear spectra are compared with these solutions, and an effort is made to relate the solutions and observations to extant models of internal wave generation and scattering.