Distribution of magnetic energy in αΩ-dynamos, II: A solar convection zone dynamo
作者:
J.H. G. M. Van Geffen,
期刊:
Geophysical & Astrophysical Fluid Dynamics
(Taylor Available online 1993)
卷期:
Volume 71,
issue 1-4
页码: 223-241
ISSN:0309-1929
年代: 1993
DOI:10.1080/03091929308203603
出版商: Taylor & Francis Group
关键词: Dynamo processes;mean-field MHD;stochastic processes;turbulence;vorticity
数据来源: Taylor
摘要:
An αomega-dynamo operating in the solar convection zone is considered as a possible explanation for the 22-year magnetic cycle of the Sun. The finite magnetic energy method of Van Geffen and Hoyng (1993) is used to find the stationary distribution of the mean magnetic energyBB, where <·> is an ensemble average. This method is based on the idea that the magnetic fieldBremains finite only ifBBremains finite. To ensure the latter, a fairly large value for the turbulent diffusion coefficient inside the convection zone is needed: β = 1014cm2s−1. Stationarity ofBBdetermines a combination of parameters, which is then used in the dynamo equation for the mean fieldB. For various profiles for the solar differential rotation we find thatBis very quickly damped: in about 14 days, a minute fraction of the solar cycle. It follows that the dynamo field in the convection zone is rapidly fluctuating and very unstable, that it has no clear period and no well-defined large-scale field: it is a small-scale field dynamo.
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