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Lookup NU author(s): Dr Craig Duguid, Professor Paul BushbyORCiD, Dr Toby Wood
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
The details of the dynamo process that is responsible for driving the solar magnetic activity cycle are still not fully understood. In particular, whilst differential rotation provides a plausible mechanism for the regeneration of the toroidal (azimuthal) component of the large-scale magnetic field, there is ongoing debate regarding the process that is responsible for regenerating the Sun’s large-scale poloidal field. Our aim is to demonstrate that magnetic buoyancy, in the presence of rotation, is capable of producing the necessary regenerative effect. Building upon our previous work, we carry out numerical simulations of a local Cartesian model of the tachocline, consisting of a rotating, fully compressible, electrically conducting fluid with a forced shear flow. An initially weak, vertical magnetic field is sheared into a strong, horizontal magnetic layer that becomes subject to magnetic buoyancy instability. By increasing the Prandtl number we lessen the back reaction of the Lorentz force onto the shear flow, maintaining stronger shear and a more intense magnetic layer. This in turn leads to a more vigorous instability and a much stronger mean electromotive force, which has the potential to significantly influence the evolution of the mean magnetic field. These results are only weakly dependent upon the inclination of the rotation vector, i.e. the latitude of the local Cartesian model. Although further work is needed to confirm this, these results suggest that magnetic buoyancy in the tachocline is a viable poloidal field regeneration mechanism for the solar dynamo.
Author(s): Duguid CD, Bushby PJ, Wood TS
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Year: 2024
Volume: 535
Issue: 1
Pages: 78-89
Print publication date: 01/11/2024
Online publication date: 11/10/2024
Acceptance date: 10/10/2024
Date deposited: 10/10/2024
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Oxford University Press
URL: https://doi.org/10.1093/mnras/stae2347
DOI: 10.1093/mnras/stae2347
Data Access Statement: The data underlying this article will be shared on reasonable request to the corresponding author.
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