Bistability and hysteresis of dipolar dynamos generated by turbulent convection in rotating spherical shells

TL;DR

This paper demonstrates the existence of bistability and hysteresis in turbulent dipolar dynamos within rotating spherical shells, revealing distinct dynamo regimes and their dependence on key parameters.

Contribution

It provides the first detailed analysis of bistability and hysteresis in turbulent dipolar dynamos in rotating spherical shells, highlighting parameter ranges and regime differences.

Findings

Hysteresis appears as a transition between two regimes with different magnetic and flow properties.

Bistability occurs from the onset of dynamo action up to about 9 times the critical Rayleigh number.

Bistability exists over a wide range of Prandtl numbers, including unity.

Abstract

Bistability and hysteresis of magnetohydrodynamic dipolar dynamos generated by turbulent convection in rotating spherical fluid shells is demonstrated. Hysteresis appears as a transition between two distinct regimes of dipolar dynamos with rather different properties including a pronounced difference in the amplitude of the axisymmetric poloidal field component and in the form of the differential rotation. The bistability occurs from the onset of dynamo action up to about 9 times the critical value of the Rayleigh number for onset of convection and over a wide range of values of the ordinary and the magnetic Prandtl numbers including the value unity.