sunspots

This video is quite helpful and well worthwhile.  We have known for some time that the orbits of Venus, Earth and Jupiter have a natural combined cycle that produces a maxima every 11.07 years which essentially coincides with the observed sunspot cycle.

Recent work proposes that this strengthening tidal effect is able to trigger  tipping events in the plasma that then cascades downwards deep into the plasma to produce the sunspot.  A little bit like a rogue wave perhaps.

This certainly explains the low volume and generally low frequency.  The overall effect is small in comparison to the Sun itself, but the phenomena itself is dangerous to the Earth environment..

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A Model of a Tidally Synchronized Solar Dynamo

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• Authors and affiliations

• F. Stefani
• A. Giesecke
• T. Weier

• F. Stefani
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• A. Giesecke
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• T. Weier
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1. 1.Helmholtz-Zentrum Dresden-RossendorfDresdenGermany

Article

First Online: 22 May 2019

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Abstract

We discuss a solar dynamo model of Tayler–Spruit type whose Ω

-effect is conventionally produced by a solar-like differential rotation but whose α-effect is assumed to be periodically modulated by planetary tidal forcing. This resonance-like effect has its rationale in the tendency of the current-driven Tayler instability to undergo intrinsic helicity oscillations which, in turn, can be synchronized by periodic tidal perturbations. Specifically, we focus on the 11.07-years alignment periodicity of the tidally dominant planets Venus, Earth, and Jupiter, whose persistent synchronization with the solar dynamo is briefly touched upon. The typically emerging dynamo modes are dipolar fields, oscillating with a 22.14-years period or pulsating with a 11.07-years period, but also quadrupolar fields with corresponding periodicities. In the absence of any constant part of α, we prove the sub-critical nature of this Tayler–Spruit type dynamo. The resulting amplitude of the α oscillation that is required for dynamo action turns out to lie in the order of 1 ms, which seems not implausible for the Sun. When starting with a more classical, non-periodic part of α, even less of the oscillatory α part is needed to synchronize the entire dynamo. Typically, the dipole solutions show butterfly diagrams, although their shapes are not convincing yet. Phase coherent transitions between dipoles and quadrupoles, which are reminiscent of the observed behavior during the Maunder minimum, can easily be triggered by long-term variations of dynamo parameters, but may also occur spontaneously even for fixed parameters. Further interesting features of the model are the typical second intensity peak and the intermittent appearance of reversed helicities in both hemispheres.