HR: 1340h
AN: GP33A-0915    [Abstracts]
TI: Numerical Investigation of a Reduced One-dimensional Model for the Geodynamo
AU: Lebrat, T
EM: lebrat@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Equipe MAG, Ecole Normale Supérieure, Département de Physique, LRA, 24 rue Lhomond, Paris, 75005, France
AU: * Dormy, E
EM: dormy@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Equipe MAG, Ecole Normale Supérieure, Département de Physique, LRA, 24 rue Lhomond, Paris, 75005, France
AB: Many simplified dynamical models can be constructed to investigate dynamo action. On the one hand, these models allow much longer simulations than three-dimensional (3D) models. They are often used to study polarity reversals and their statistics. On the other hand, they are very remote from the dynamics of the Earth outer core. We present non-linear numerical results obtained with an original one-dimensional (1D) model. This model is obtained from a truncation of the governing equations for the geodynamo written under the quasi-geostrophic formalism. The resulting model, although very simplified, relies on the same non-dimensional parameters as fully 3D simulations (i.e. Ekman, Prandtl, magnetic Prandtl and Rayleigh numbers). The spatial description is limited to a few modes, explicitly coupled, so that the integration time is much less constrained as well as the accessible parameter range. We compare the results of our 1D model of the geodynamo to those of 3D simulations, discuss dynamical and statistical properties of these models, and their applicability to investigate the dynamics of the Earth core.
DE: 1510 Dynamo: theories and simulations
DE: 4410 Bifurcations and attractors
DE: 5734 Magnetic fields and magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting