Numerical Simulations of Internal Waves Generated by Flow over a Ridge

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Title: Numerical Simulations of Internal Waves Generated by Flow over a Ridge
Author: Qian, Hui
Advisors: Ruoying He, Committee Member
Ping-Tung Shaw, Committee Chair
Gerald S. Janowitz, Committee Member
Abstract: QIAN, HUI. Numerical Simulations of Internal Waves Generated by Flow over a Ridge. (Under the direction of Dr. Ping-Tung Shaw). A three-dimensional nonhydrostatic numerical model is used to study the generation of internal wave energy by barotropic tidal flow over a steep ridge. Numerical experiments are carried out over ridges of three different heights in an ocean with strong stratification at shallow depths. The topographic width, stratification, and amplitude of the barotropic tide are varied to examine the dependence of the normalized energy flux on the slope parameter, the ratio of the ridge slope to that of the wave beam. Over a tall ridge reaching the strongly stratified depths of the water column, the non-dimensional energy flux increases with the slope parameter and becomes constant when the slope parameter exceeds a critical value. For a small ridge confined at weakly stratified depths, the non-dimensional energy flux reaches a maximum with increase in the slope parameter but decreases with further increase in the slope parameter. The two regimes of dependence on the slope parameter can be described in terms of a local Froude number. The results show that internal wave generation is most efficient when the ridge is steep and the ridge top reaches the strongly stratified upper ocean. Comparison between the parameterization scheme and the estimated energy flux at several locations in the ocean shows reasonable agreement. The non-dimensional relation provides a way to estimate the baroclinic energy flux using topographic scales, stratification, and strength of the barotropic tides in the ocean.
Date: 2010-04-02
Degree: MS
Discipline: Marine, Earth and Atmospheric Sciences
URI: http://www.lib.ncsu.edu/resolver/1840.16/6330


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