Cycles and cycle modulations

TL;DR

This paper reviews concepts of solar activity cycles, examines cycle modulations via stochastic effects, compares turbulence simulations at different scales, and discusses implications for sunspot origins and active region tilts.

Contribution

It introduces new insights into cycle modulations, turbulence simulation comparisons, and the role of shear in active region tilts, advancing understanding of solar magnetic phenomena.

Findings

Fluctuation levels are relatively stable across dynamo cycles.

Cycle modulations can be linked to stochastic alpha effects.

Shear influences tilt angles more than the Coriolis force.

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.