Geomagnetic field and dipole moment of the past 7 millennia

Monika Korte
GeoForschungsZentrum 
Postdam Germany

ABSTRACT

The evolution of the geomagnetic field prior to times of direct observation is 
studied by analyzing the remantent magnetization of archeological material, lava 
flows and lake sediments. The amount of sufficiently accurately dated results 
from worldwide locations has become large enough to allow for the development of 
continuous global models on the millennial time scale. Features like spectral 
power distribution, evolution of the geomagnetic dipole moment and large-scale 
magnetic flux distribution at the core-mantle boundary probably linked to 
core-mantle coupling mechanisms can be studied from global models. I will 
present the latest global model covering the past 7000 years and discuss some of 
its implications. Particular attention will be given to the dipole moment 
evolution and its comparison to previous results from virtual (axial) dipole 
moment (VDM, VADM) studies.