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The Solar Dynamo

Thompson, M.J. and Weiss, N.O. (2009) The Solar Dynamo. Space Science Reviews, 144 (1-4). pp. 53-66. ISSN 1572-9672

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Abstract

It is generally accepted that the strong toroidal magnetic fields that emerge through the solar surface in sunspots and active regions are formed by the action of differential rotation on a poloidal field, and then stored in or near the tachocline at the base of the Sun’s convection zone. The problem is how to explain the generation of a reversed poloidal field from this toroidal flux—a process that can be parametrised in terms of an α-effect related to some form of turbulent helicity. Here we first outline the principal patterns that have to be explained: the 11-year activity cycle, the 22-year magnetic cycle and the longer term modulation of cyclic activity, associated with grand maxima and minima. Then we summarise what has been learnt from helioseismology about the Sun’s internal structure and rotation that may be relevant to our subject. The ingredients of mean-field dynamo models are differential rotation, meridional circulation, turbulent diffusion, flux pumping and the α-effect: in various combinations they can reproduce the principal features that are observed. To proceed further, it is necessary to rely on large-scale computation and we summarise the current state of play.

Item Type: Article
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield)
Depositing User: Mrs Megan Hobbs
Date Deposited: 09 Mar 2010 15:07
Last Modified: 09 Mar 2010 15:07
Published Version: http://dx.doi.org/10.1007/s11214-008-9435-z
Status: Published
Publisher: Springer
Identification Number: 10.1007/s11214-008-9435-z
URI: http://eprints.whiterose.ac.uk/id/eprint/10481

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