Magnetic helicity evolution during the solar activity cycle: Observations and dynamo theory

Free access article

Issue		A&A Volume 409, Number 3, October III 2003


Page(s)		1097 - 1105
Section		Diffuse matter in space
DOI		http://dx.doi.org/10.1051/0004-6361:20031126

A&A 409, 1097-1105 (2003)
DOI: 10.1051/0004-6361:20031126

Magnetic helicity evolution during the solar activity cycle: Observations and dynamo theory

N. Kleeorin¹, K. Kuzanyan², D. Moss³, I. Rogachevskii¹, D. Sokoloff⁴ and H. Zhang⁵

¹ Department of Mechanical Engineering, Ben-Gurion University of Negev, POB 653, 84105 Beer-Sheva, Israel
    e-mail: nat@menix.bgu.ac.il;gary@bgumail.bgu.ac.il
² IZMIRAN, Troitsk, Moscow Region 142190, Russia
    e-mail: kuzanyan@dnttm.ru
³ Department of Mathematics, University of Manchester, Manchester M13 9PL, UK
    e-mail: moss@maths.man.ac.uk
⁴ Department of Physics, Moscow State University, Moscow 119992, Russia
    e-mail: sokoloff@dds.srcc.msu.su
⁵ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
    e-mail: hzhang@bao.ac.cn

(Received 14 April 2003 / accepted 15 July 2003 )

Abstract
We study a simple model for the solar dynamo in the framework of the Parker migratory dynamo, with a nonlinear dynamo saturation mechanism based on magnetic helicity conservation arguments. We find a parameter range in which the model demonstrates a cyclic behaviour with properties similar to that of Parker dynamo with the simplest form of algebraic $\alpha$ -quenching. We compare the nonlinear current helicity evolution in this model with data for the current helicity evolution obtained during 10 years of observations at the Huairou Solar Station of China. On one hand, our simulated data demonstrate behaviour comparable with the observed phenomenology, provided that a suitable set of governing dynamo parameters is chosen. On the other hand, the observational data are shown to be rich enough to reject some other sets of governing parameters. We conclude that, in spite of the very preliminary state of the observations and the crude nature of the model, the idea of using observational data to constrain our ideas concerning magnetic field generation in the framework of the solar dynamo appears promising.

Key words: Sun: magnetic fields

Offprint request: I. Rogachevskii, gary@bgumail.bgu.ac.il

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