The combined effect of precession and convection on the dynamo action

TL;DR

This study numerically investigates how the combined effects of precession and convection can enable dynamo action in planetary cores, highlighting resonance phenomena that support magnetic field generation.

Contribution

It demonstrates that the combined precession and convection effects can sustain dynamo action through resonance, a novel insight into planetary magnetic field generation.

Findings

Precession or convection alone cannot sustain dynamo.

Combined effects can support dynamo via resonance.

Explains long-lived Earth's geodynamo compared to Mars.

Abstract

To understand the generation of the Earth's and planetary magnetic fields, we investigate numerically the combined effect of precession and convection on the dynamo action in a spherical shell. The convection alone, the precession alone and the combined effect of convection and precession are studied at the low Ekman number at which the precessing flow is already unstable. The key result is that although the precession or convection alone is not strong to support the dynamo action the combined effect of precession and convection can support the dynamo action because of the resonance of precessional and convective instabilities. This result may interpret why the geodynamo maintains for such a long history compared to the Martian dynamo.