Axisymmetric inertial gravity oscillations of a compressible stratified fluid in a rigid sphere : an approximation of the Earth's outer core

Webb, Susan Jane (1992) Axisymmetric inertial gravity oscillations of a compressible stratified fluid in a rigid sphere : an approximation of the Earth's outer core. Masters thesis, Memorial University of Newfoundland.

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Abstract

This thesis investigates several theoretical methods for solving the sub-seismic wave equation (SSWE) in an incompressible or slightly stratified liquid bounded by a rigid fixed spherical boundary as an approximation to the Earth's liquid core. The solution of the SSWE yields eigenvalues for the inertia/gravity wave spectrum. The first method considered uses a variational principle based on a more general functional than has been previously used to evaluate the SSWE. The resulting eigenvalues are compared with previous work done by Aldridge and Toomre (1969). The work is then extended to include a density profile and a shift is noted in the eigenspectrum. A perturbation approach was used to include stably stratified regions characterised by negative values of the stability parameter B; unfortunately this method only works for such small values of B as to be uninteresting. Finally a Galerkin approach was adopted that allows for the evaluation of negative B values. This results in a further change of the inertial eigenspectrum and the appearance of gravity modes.

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