Bistability between Equatorial and Axial Dipoles during Magnetic Field Reversals | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Bistability between Equatorial and Axial Dipoles during Magnetic Field Reversals

Type de publication:

Journal Article

Source:

Physical Review Letters, Volume 108, Ticket 23 (2012)

ISBN:

0031-9007

URL:

http://prl.aps.org/abstract/PRL/v108/i23/e234501

Mots-clés:

UMR 7154 ; Géomagnétisme

Résumé:

Numerical simulations of the geodynamo in the presence of heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m 0 axial dipolar field is replaced by a hemispherical magnetic field, dominated by an oscillating m 1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of Earth's dynamo.

Notes:

Times Cited: 0