The Earth's Slichter modes
Date
2013
Authors
Mamboukou, Michel Nzikou
Journal Title
Journal ISSN
Volume Title
Publisher
Lethbridge, Alta. : University of Lethbridge, Dept. of Physics and Astronomy, c2013
Abstract
Numerical methods have been used to predict the eigenperiods and eigenfunctions of the
Earth’s Slichter modes, known as the Slichter triplets. In order to test the validity of our
method, we have also computed the frequencies and displacement eigenfunctions of some of
the inertial modes of the Earth’s fluid core. We use a Galerkin method to integrate the Three
Potential Description (3PD) for a neutrally, stratified and rotating fluid core of a modified
Preliminary Reference Earth Model (PREM). Moreover, the same mathematical tool is used
for the computation of the frequencies and displacement amplitudes of the Slichter modes.
In the Galerkin formulation of the 3PD, using the divergence theorem, we make use of the
natural character of the boundary conditions to reduce the order of derivatives from second
to first. To compute the frequencies of the Slichter modes, we solve simultaneously the
equations of the inner core motion and the dynamics of the fluid core as described above.
The results are compared to those in previous studies and it is shown that in the case of the
inertial modes they agree well, which proves the validity of the approach. For the Slichter
modes, however, it is shown that the results are significantly different from previous work
for a similar Earth model. We have also plotted the displacement eigenfunctions for the
motion of the fluid in the fluid core during the Slichter oscillations. It is shown that the
pattern of motion is consistent with the motion of the inner core, which serves as a second test of the validity of our results.
Description
x, 105 leaves : ill. ; 29 cm
Keywords
Earth (Planet) -- Core -- Mathematical models , Eigenfunctions , Galerkin methods , Dissertations, Academic