Open Questions and Current Trends
I close this review with the following discussion of a few open questions that, in my opinion, bear particularly heavily on our understanding (or lack thereof) of the solar cycle.
What is the primary poloidal field regeneration mechanism?
What limits the amplitude of the solar magnetic field?
Flux tubes versus diffuse fields
How constraining is the sunspot butterfly diagram?
Is meridional circulation crucial?
Is the mean solar magnetic field really axisymmetric?
What causes Maunder-type Grand Minima?
"Dynamo Models of the Solar Cycle"
© Max Planck Society and the author(s)