Normal modes of realistic Earth models: an advanced treatment of elasticity, rotation and fluid core compressibility
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Date
2021
Authors
KAMRUZZAMAN, MD
University of Lethbridge. Faculty of Arts and Science
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Publisher
Lethbridge, Alta. : University of Lethbridge, Dept. of Physics & Astronomy
Abstract
We apply the Galerkin method to solve the linear momentum description (LMD) of the dynamics of the Earth's layers and expand the Galerkin formulation of the LMD to include the first order ellipticity using the Clairaut coordinate system in order to study the Earth's normal modes. We show that the computed frequencies of the inertial modes may be significantly affected by the elasticity of the mantle and inner core. Traditionally, a liquid core with rigid boundaries is considered to study these modes. Our computed periods of the Chandler wobble (CW) and the free core nutation (FCN) are not affected by the density stratification of the fluid core. The computed period of the FCN, 432.28 sd, is almost identical to the observed value. This indicates that the Earth is indeed in hydrostatic equilibrium which is in contrast to previous work suggested that the Earth deviated from hydrostatic equilibrium. The great advantage of our method is that we can ensure the frequencies are converged.
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Keywords
Earth's normal modes , Inertial modes , Wobble and nutation modes , Slichter modes and Rotation of Earth , Astronautics in geophysics , Dissertations, Academic , Earth (Planet) -- Core -- Mathematical models , Earth (Planet) -- Rotation. , Earth (Planet)--Core , Earth resistance (Geophysics) , Nutation