The geomagnetic secular-variation timescale in observations and numerical dynamo models | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  The geomagnetic secular-variation timescale in observations and numerical dynamo models

Type de publication:

Journal Article

Source:

Geophysical Research Letters, Volume 38 (2011)

ISBN:

0094-8276

Numéro d'accès:

WOS:000290443000001

URL:

http://www.agu.org/pubs/crossref/2011/2011GL047356.shtml

Mots-clés:

UMR 7154 ; Géomagnétisme

Résumé:

<p>The knowledge of the spatial power spectra of the main geomagnetic field and of its secular variation makes it possible to define typical timescales tau(n) for each spherical harmonic degree n. Investigating both observations and numerical dynamos, we show that a one-parameter law of the form tau(n) = tau(SV)/n is satisfied for the non-dipole field, given the statistical way the observed tau(n) are expected to fluctuate. Consequently, we determine the corresponding secular-variation timescale tau(SV) from either instantaneous or time-averaged spectra, leading to a value of 415 +/-(55)(45) yr for recent satellite field models. In the broader context of geomagnetic data assimilation, tau(SV) could provide a sensible and convenient means to rescale the time axis of dynamo simulations. Citation: Lhuillier, F., A. Fournier, G. Hulot, and J. Aubert (2011), The geomagnetic secular-variation timescale in observations and numerical dynamo models, Geophys. Res. Lett., 38, L09306, doi: 10.1029/2011GL047356.</p>

Notes:

Lhuillier, Florian Fournier, Alexandre Hulot, Gauthier Aubert, Julien