Toroidal flux oscillation as possible cause of geomagnetic excursions and reversals

TL;DR

This paper suggests that oscillations in the toroidal magnetic flux within planetary core dynamos could explain geomagnetic excursions and reversals, supported by simulation evidence showing internal magnetic flux oscillations linked to observable geomagnetic phenomena.

Contribution

It introduces the idea that internal toroidal flux oscillations in planetary dynamos can cause geomagnetic excursions and reversals, supported by simulation examples.

Findings

Simulations show oscillations in toroidal flux without external field variations.

Oscillations may lead to geomagnetic reversals.

Some similarities between simulations and paleomagnetic data are observed.

Abstract

It is proposed that convection driven dynamos operating in planetary cores could be oscillatory even when the oscillations are not directly noticeable from the outside. Examples of dynamo simulations are pointed out that exhibit oscillations in the structure of the azimuthally averaged toroidal magnetic flux while the mean poloidal field shows only variations in its amplitude. In the case of the geomagnetic field, global excursions may be associated with these oscillations. Long period dynamo simulations indicate that the oscillations may cause reversals once in a while. No special attempt has been made to use most realistic parameter values. Nevertheless some similarities between the simulations and the paleomagnetic record can be pointed out.