Cycles and cycle modulations
Solar and Stellar Astrophysics
2012-07-17 v1
Abstract
Some selected concepts for the solar activity cycle are briefly reviewed. Cycle modulations through a stochastic alpha effect are being identified with limited scale separation ratios. Three-dimensional turbulence simulations with helicity and shear are compared at two different scale separation ratios. In both cases the level of fluctuations shows relatively little variation with the dynamo cycle. Prospects for a shallow origin of sunspots are discussed in terms of the negative effective magnetic pressure instability. Tilt angles of bipolar active regions are discussed as a consequence of shear rather than the Coriolis force.
Keywords
Cite
@article{arxiv.1111.3351,
title = {Cycles and cycle modulations},
author = {Axel Brandenburg and Gustavo Guerrero},
journal= {arXiv preprint arXiv:1111.3351},
year = {2012}
}
Comments
12 pages, 5 figures, to appear in Proceedings of IAU Symp 286, Comparative Magnetic Minima, C. H. Mandrini, eds