A study of global magnetic helicity in self-consistent spherical dynamos

Gupta, P., Simitev, R.D. and MacTaggart, D. (2022) A study of global magnetic helicity in self-consistent spherical dynamos. Geophysical and Astrophysical Fluid Dynamics, 116(5-6), pp. 521-536. (doi: 10.1080/03091929.2022.2137878)

Abstract

Magnetic helicity is a fundamental constraint in both ideal and resistive magnetohydrodynamics. Measurements of magnetic helicity density on the Sun and other stars are used to interpret the internal behaviour of the dynamo generating the global magnetic field. In this note, we study the behaviour of the global relative magnetic helicity in three self-consistent spherical dynamo solutions of increasing complexity. Magnetic helicity describes the global linkage of the poloidal and toroidal magnetic fields (weighted by magnetic flux), and our results indicate that there are preferred states of this linkage. This leads us to propose that global magnetic reversals are, perhaps, a means of preserving this linkage, since, when only one of the poloidal or toroidal fields reverses, the preferred state of linkage is lost. It is shown that magnetic helicity indicates the onset of reversals and that this signature may be observed at the outer surface.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mactaggart, Dr David and Simitev, Professor Radostin and Gupta, Parag
• Authors: Gupta, P., Simitev, R.D., and MacTaggart, D.
• College/School: College of Science and Engineering > School of Mathematics and Statistics > Mathematics
• Journal Name: Geophysical and Astrophysical Fluid Dynamics
• Publisher: Taylor and Francis
• ISSN: 0309-1929
• ISSN (Online): 1029-0419
• Published Online: 08 November 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Geophysical and Astrophysical Fluid Dynamics 116(5-6): 521-536
• Publisher Policy: Reproduced under a Creative Commons licence