Kinematic validation of a quasi-geostrophic model for the fast dynamics in the Earth's outer core
- Journal Article
Rights / licenseIn Copyright - Non-Commercial Use Permitted
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. Show more
Journal / seriesGeophysical Journal International
Pages / Article No.
PublisherOxford University Press
SubjectCore; Rapid time variations; Numerical modelling
Organisational unit03734 - Jackson, Andrew / Jackson, Andrew
143596 - The geomagnetic field over multiple time scales: Measurements, models, and mechanisms (SNF)
NotesIt was possible to publish this article open access thanks to a Swiss National Licence with the publisher.
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