Internal Tide Generation by Tall Ocean Ridges

Paula Echeverri Mondragón, Ph.D., 2009
Thomas Peacock, Advisor

Tall, nominally two-dimensional submarine ridges are sites of strong internal tide generation. The dissipation of internal tides plays a role in ocean circulation, and strong internal tides can evolve into solitons, which affect engineered ocean systems.

First, a pre-existing Green function formulation for internal tide generation by symmetric ridges in uniform density stratifications is investigated experimentally. The theory accurately predicts the low-mode structure of internal tides, and reasonably predicts the baroclinic conversion rate in finite tidal excursion regimes, for which non-linearities are notable in the laboratory.

Second, the Green function method is advanced for asymmetric and multiple ridges. Results reveal that internal tide asymmetry can be sensitive to geometric configuration. The approach is used with oceanographic data to predict the internal tide generated at Hawaii and at the Luzon Strait. There is reasonable agreement with previous studies.

Finally, internal wave attractors in double-ridge configurations are investigated. A map is developed to identify the existence and stability of attractors as a function of the ridge geometry. Dissipation is included in the theory to balance energy focusing along an attractor. Good agreement is obtained between experiment and theory, even in the presence of an attractor.