Observations of internal wave reflection off sloping bottoms

TLDR

Internal waves alter their energy density, wavenumber, and azimuth when reflecting from sloping bottoms, thereby perturbing the deep ocean internal wave spectrum. The study examines this phenomenon using observations from islands, seamounts, and continental slopes. Spectra near sloping bottoms show intensified, polarized signals around the local critical frequency, deviations from linear theory indicating dissipation via shear instability or nonlinear interactions, and suggest that topographic features act as energy sinks for internal wave energy.

Abstract

Current and temperature spectra exhibit intensification and polarization near sloping bottoms over a band of frequencies centered at the local internal wave critical frequency. Examples are drawn from a variety of island, seamount, and continental slope observations. Waves propagating down from mid‐depth change energy density, wave number, and azimuth when they reflect off the bottom, providing a natural perturbation to the deep ocean interior internal wave spectrum. Deviations from linear theory are interpreted as evidence for dissipation through subsequent shear instability and/or nonlinear interaction. Topographic features appear likely to be energy sinks for internal wave energy.