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I am currently involved in a project studying the dissipation of internal waves generated by the tides, with Dr. Jen MacKinnon at Scripps Oceanographic Institution.
This project was born out of my participation at the Woods Hole GFD Summer School.
Research has suggested that the global ocean circulation is significantly influenced by the breaking of internal waves, though the sources and sinks of internal wave energy in the world ocean are not well understood. One source is the flow of the barotropic tide over topography, which generates internal waves with the same frequency as the tide. Breaking of these waves break depends on the location of topography, but also on the fundamental mechanisms that cause the internal tide to cascade to smaller scales. Numerical experiments of of MacKinnon and Winters (2004) showed that an internal wave of tidal frequency efficiently breaks into waves of roughly half this frequency, and that this interaction becomes dramatically more efficient at the critical latitude where the half-frequency equals the inertial frequency ($f$). This suggests that resonant interactions known as Parametric Subharmonic Instability (PSI) could be a significant energy cascade mechanism, but it remains unclear why the efficiency of these interactions should increase so much near the critical latitude. My work is focused on understanding the latitude dependence of PSI, by considering the effect of the Coriolis force in the traditional analytical derivation of resonant triad interactions, and then examining the resulting simple model numerically. |
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