Stationary, oscillating or drifting mantledriven geomagnetic
and Gauthier Hulot1
Received 15 April 2009; revised 23 December 2009; accepted 25 February 2010; published 27 July 2010.
 The impact of the heterogeneous lower mantle on the geomagnetic field is under debate,
especially the question of whether highlatitude intense geomagnetic flux patches currently
observed at the core surface are stationary, oscillating, or drifting on longer time scales.
While the correlation between the location of these patches with that of similar patches found
in the timeaveraged paleomagnetic field may suggest stationary behavior, their variability
over archaeomagnetic time scales together with their weaker signature in the average
paleomagnetic field relative to the present geomagnetic field precludes such a scenario. Here
we use numerical dynamos with an imposed heat flux boundary condition based on
lower mantle tomography to study the behavior of such intense magnetic flux patches.