Maffei, S orcid.org/0000-0002-1603-4040 and Jackson, A (2017) Kinematic validation of a quasi-geostrophic model for the fast dynamics in the Earth’s outer core. Geophysical Journal International, 210 (3). pp. 1772-1786. ISSN 0956-540X
Abstract
We derive a quasi-geostrophic (QG) system of equations suitable for the description of the Earth’s core dynamics on interannual to decadal timescales. Over these timescales, rotation is assumed to be the dominant force and fluid motions are strongly invariant along the direction parallel to the rotation axis. The diffusion-free, QG system derived here is similar to the one derived in Canet et al. but the projection of the governing equations on the equatorial disc is handled via vertical integration and mass conservation is applied to the velocity field. Here we carefully analyse the properties of the resulting equations and we validate them neglecting the action of the Lorentz force in the momentum equation. We derive a novel analytical solution describing the evolution of the magnetic field under these assumptions in the presence of a purely azimuthal flow and an alternative formulation that allows us to numerically solve the evolution equations with a finite element method. The excellent agreement we found with the analytical solution proves that numerical integration of the QG system is possible and that it preserves important physical properties of the magnetic field. Implementation of magnetic diffusion is also briefly considered.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This article has been accepted for publication in Geophysical Journal International. © The Authors 2017. Published by Oxford University Press on behalf of The Royal Astronomical Society. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | Core, Rapid time variations, Numerical modelling |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 27 Feb 2020 14:12 |
Last Modified: | 28 Feb 2020 09:30 |
Status: | Published |
Publisher: | Oxford University Press (OUP) |
Identification Number: | 10.1093/gji/ggx263 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:157693 |