Internal wave beam propagation in non-uniform stratifications

In addition to being observable in laboratory experiments, internal wave beams are reported in geophysical settings, which are characterized by nonuniform density stratifications. Here, we perform a combined theoretical and experimental study of the propagation of internal wave beams in nonuniform density stratifications. Transmission and reflection coefficients, which can differ greatly for different physical quantities, are determined for sharp density-gradient interfaces and finite-width transition regions, accounting for viscous dissipation. Thereafter, we consider even more complex stratifications to model geophysical scenarios. We show experimentally that wave beam ducting can occur under conditions that do not necessitate evanescent layers. Comparisons between the theory and quantitative experimental measurements of these processes show excellent agreement. Insights into wave beam observations at the Keana ridge, Hawaii are given within the context of these ideas.