The Environmental Fluid Mechanics/Hydrology Series

Internal Wave Breaking on Submerged Topographic Features

Abstract:
Internal wave interactions with topography have important implications for mixing and transport processes on local and global scales. Although implications for oceanic diapycnal mixing are significant, internal wave breaking processes at ridges and seamounts are not completely understood. Laboratory experiments on the interactions between monochromatic, periodic wave trains and Gaussian ridge are used to isolate and analyze specific processes such as harmonic wave generation over the ridge and instability mechanisms in wave breaking. The nature of the wave-ridge interaction is dependent on characteristics of the incident waves and the topography geometry. During more intense wave-ridge interactions, progressive waves can be forced to break over the ridge. Both shear and convective instabilities can contribute to wave breaking in this case. A classification scheme has been suggested to parameterize breaking behavior based on wave and topographic scales. Planar Laser-Induced Fluorescence and Particle Imaging Velocimetry techniques are used to determine the length scales and energy balances associated with breaking events. The results are compared in a Reynolds Number-Froude Number domain with other stratified turbulence experiments and observations.