Magnetic field reversals and long-time memory in conducting flows

TL;DR

This paper demonstrates that rotation or magnetic helicity in a simple magnetohydrodynamic model can cause magnetic dipole reversals, resembling Earth's magnetic field behavior, and links long-term correlations with reversal statistics.

Contribution

It introduces a minimal ideal MHD model showing how rotation or magnetic helicity induce magnetic reversals and long-time memory effects.

Findings

Reversals occur with either rotation or magnetic helicity.

Model exhibits statistical features similar to Earth's magnetic field reversals.

Long time correlations and 1/f noise are connected to reversal dynamics.

Abstract

Employing a simple ideal magnetohydrodynamic model in spherical geometry,we show that the presence of either rotation or finite magnetic helicity is sufficient to induce dynamical reversals of the magnetic dipole moment. The statistical character of the model is similar to that of terrestrial magnetic field reversals, with the similarity being stronger when rotation is present.The connection between long time correlations, $1/f$ noise, and statistics of reversals is supported, consistent with earlier suggestions.