Journal Article

The influence of α-effect fluctuations and the shear-current effect upon the behaviour of solar mean-field dynamo models

P. J. Bushby and M. R. E. Proctor

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 409, issue 4, pages 1611-1618
Published in print December 2010 | ISSN: 0035-8711
Published online December 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17405.x
The influence of α-effect fluctuations and the shear-current effect upon the behaviour of solar mean-field dynamo models

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Recent numerical and analytical work has identified a possible new source of mean-field dynamo action, caused by fluctuations in the α-effect interacting with a large-scale shear. This process gives rise to a new source term in the averaged induction equation. Essentially the same term arises from the shear-current effect. This paper investigates the consequences of the new term in a two-dimensional solar dynamo model, in spherical geometry, with a realistic large-scale shear. In general, it is found that the new source term leads to an increase in the dynamo cycle period, although the details of this depend crucially upon the spatial variation of the fluctuations in the α-effect (or the shear-current term). Steady magnetic fields are generated when the new term plays a dominant role in the dynamo process.

Keywords: magnetic fields; MHD; turbulence; Sun: activity; Sun: dynamo

Journal Article.  5229 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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