  We discuss a solar dynamo model of Tayler-Spruit type whose Omega-effect is
conventionally produced by a solar-like differential rotation but whose
alpha-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 alpha, we prove the
subcritical nature of this Tayler-Spruit type dynamo. The resulting amplitude
of the alpha oscillation that is required for dynamo action turns out to lie in
the order of 1 m/s, which seems not implausible for the sun. When starting with
a more classical, non-periodic part of alpha, even less of the oscillatory
alpha 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 behaviour during the Maunder minimum, can be easily
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.
