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Space Sci Rev DOI 10.1007/s11214-010-9684-5

Summary: Space Sci Rev
DOI 10.1007/s11214-010-9684-5
Observations and Models of the Long-Term Evolution
of Earth's Magnetic Field
Julien Aubert John A. Tarduno Catherine L. Johnson
Received: 2 June 2010 / Accepted: 3 August 2010
Springer Science+Business Media B.V. 2010
Abstract The geomagnetic signal contains an enormous temporal range--from geomag-
netic jerks on time scales of less than a year to the evolution of Earth's dipole moment over
billions of years. This review compares observations and numerical models of the long-term
range of that signal, for periods much larger than the typical overturn time of Earth's core.
On time scales of 105
years, the geomagnetic field reveals the control of mantle ther-
modynamic conditions on core dynamics. We first briefly describe the general formalism
of numerical dynamo simulations and available paleomagnetic data sets that provide insight
into paleofield behavior. Models for the morphology of the time-averaged geomagnetic field
over the last 5 million years are presented, with emphasis on the possible departures from
the geocentric axial dipole hypothesis and interpretations in terms of core dynamics. We
discuss the power spectrum of the dipole moment, as it is a well-constrained aspect of the


Source: Aubert, Julien - Institut de Physique du Globe de Paris


Collections: Geosciences