Three Branches of Dynamo Action

TL;DR

This paper discusses a third, strong-dipolar dynamo regime identified in numerical models, which approaches Earth's core conditions and has implications for geodynamo understanding.

Contribution

It introduces and analyzes a third dynamo regime, the strong-dipolar branch, expanding the understanding of magnetic field states in geodynamo models.

Findings

Identification of a strong-dipolar regime in numerical models

Transitions between different dynamo states analyzed

Relevance to Earth's core dynamics established

Abstract

In addition to the weak-dipolar state and to the fluctuating-multipolar state, widely discussed in the literature, a third regime has been identified in Dormy (2016). It corresponds to a strong-dipolar branch which appears to approach, in a numerically affordable regime, the magnetostrophic limit relevant to the dynamics of the Earth's core. We discuss the transitions between these states and point to the relevance of this strong-dipolar state to Geodynamo modelling.