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Geophys. J. Int. (2008) 175, 913924 doi: 10.1111/j.1365-246X.2008.03948.x GJIGeomagnetism,rockmagnetismandpalaeomagnetism
 

Summary: Geophys. J. Int. (2008) 175, 913­924 doi: 10.1111/j.1365-246X.2008.03948.x
GJIGeomagnetism,rockmagnetismandpalaeomagnetism
Accounting for magnetic diffusion in core flow inversions
from geomagnetic secular variation
Hagay Amit1
and Ulrich R. Christensen2
1Equipe de G´eomagn´etisme, Institut de Physique du Globe de Paris (Institut de Recherche associ´e au CNRS et `a l'Universit´e Paris 7), 4 Place Jussieu,
75252 Paris Cedex 05, France. E-mail: hagay@ipgp.jussieu.fr
2Max-Planck-Institut f¨ur Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany
Accepted 2008 August 26. Received 2008 August 22; in original form 2008 April 24
S U M M A R Y
We use numerical dynamos to investigate the possible role of magnetic diffusion at the top of
the core. We find that the contribution of radial magnetic diffusion to the secular variation is
correlated with that of tangential magnetic diffusion for a wide range of control parameters.
The correlation between the two diffusive terms is interpreted in terms of the variation in
the strength of poloidal flow along a columnar flow tube. The amplitude ratio of the two
diffusive terms is used to estimate the probable contribution of radial magnetic diffusion to
the secular variation at Earth-like conditions. We then apply a model where radial magnetic
diffusion is proportional to tangential diffusion to core flow inversions of geomagnetic secular
variation data. We find that including magnetic diffusion does not change dramatically the

  

Source: Amit, Hagay - Institut de Physique du Globe de Paris

 

Collections: Geosciences