Geomagnetic Field Reversals—a Link between Strength and Orientation of a Dipole Source

Abstract

LILLEY1 has put forward the hypothesis that “the deviation of the geomagnetic axial dipole from true north, the expected axis of symmetry, is in fact an expression of the asymmetric motion of the Earth's core”. Subsequently he argues that if and when the geomagnetic and geographic poles coincide the flow pattern in the core will be symmetrical and incapable of giving a dynamo generated field. Thus he suggests the dipole may vanish and perhaps even be reversed when the flow again becomes sufficiently asymmetric to regenerate the field. He also states that, as a corollary, strong dipole fields may accompany large deviations of the magnetic north pole from the geographic north pole.