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PV-Induced Forcing of Gravity Waves in a Shallow Water Model

The influence of a geostrophically balanced or potential vorticity (PV) background flow on gravity wave propagation is examined using a rotating shallow water model. The system is analyzed in the context of a perturbative expansion that focuses on the dynamics of the resonances within the nonlinear terms of the system. The nonlinearity is reconstructed as a wave-wave interaction forcing on an otherwise undisturbed linear wavefield. The principal conclusion is that while the PV flow is generally undisturbed by the gravity wavefield, the gravity wavefield is forced by the geostrophic flow over moderate timescales. We numerically test these results for the interaction between a single geostrophic mode and a gravity wave, followed by propagation of a single gravity mode through a turbulent PV background. We find that the gravity mode energy is scattered into other modes of similar wavelength but different directions of propagation. The rate of dispersion is in agreement with resonant triad theory, where the rate depends primarily on the initial gravity wavenumber and background PV strength. These results are expected to have relevance to the propagation of coherent internal tides in the open ocean.} / A Dissertation Submitted to the Geophysical Fluid Dynamics Institute in Partial
FulīŦLlment of the Requirements for the Degree of Doctor of Philosophy. / Spring Semester, 2008. / March 26, 2008. / Gravity Waves, Shallow Water Model, Potential Vorticity, Wave Interaction, Tidal Waves / Includes bibliographical references. / Philip Cunningham, Professor Directing Dissertation; Janet Peterson, Outside Committee Member; Carol Anne Clayson, Committee Member; William K. Dewar, Committee Member; Ruby Krishnamurti, Committee Member.

Identiferoai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_175796
ContributorsWard, Marshall (authoraut), Cunningham, Philip (professor directing dissertation), Peterson, Janet (outside committee member), Clayson, Carol Anne (committee member), Dewar, William K. (committee member), Krishnamurti, Ruby (committee member), Program in Geophysical Fluid Dynamics (degree granting department), Florida State University (degree granting institution)
PublisherFlorida State University, Florida State University
Source SetsFlorida State University
LanguageEnglish, English
Detected LanguageEnglish
TypeText, text
Format1 online resource, computer, application/pdf
RightsThis Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them.

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