Date of Award

Winter 2008

Project Type

Thesis

Program or Major

Mechanical Engineering

Degree Name

Master of Science

First Advisor

Gregory P Chini

Abstract

The mixed layer is a region of enhanced mass, momentum and heat transport and as such is thought to significantly impact both the large and small scale processes in the ocean and atmosphere. Langmuir circulation (LC) and internal waves (IW) have been shown to be dominant contributors to upper ocean mixing and have, though separately, been studied extensively; however, little is known about how they interact. Langmuir circulation is a wind and surface-wave driven instability that manifests as counter-rotating vortices roughly aligned with the wind. Internal waves, whose surface signatures are often visible from ships and satellites, have the ability to transport energy and momentum great distances from their source regions. Here, pseudospectral numerical simulations (using a Fourier/Chebyshev-tau scheme) of LC and IWs are performed with the aim of investigating interactions for both two-layer-like and linearly-stratified background density profiles. Preliminary results suggest that commensurate-scale LC and IWs nonlinearly interact in a two-layer scenario with the IW frequency greatly increased by the coupling and that downward propagating IWs may be generated by mixed-layer confined LC. In the continuously stratified scenario, a novel periodic cross-wind vacillation in the position of the cells is also observed.

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