  Recent analyses of helioseismological observations seem to suggest the
presence of two new phenomena connected with the dynamics of the solar
convective zone. Firstly, there are present torsional oscillations with periods
of about 11 years, which penetrate significantly into the solar convection zone
and secondly, oscillatory regimes exist near the base of the convection which
are markedly different from those observed near the top, having either
significantly reduced periods or being non-periodic.
  Recently spatiotemporal fragmentation/bifurcation has been proposed as a
possible dynamical mechanism to account for such observed multi-mode behaviours
in different parts of the solar convection zone. Evidence for this scenario was
produced in the context of an axisymmetric mean field dynamo model operating in
a spherical shell, with a semi-open outer boundary condition and a zero order
angular velocity obtained by the inversion of the MDI data, in which the only
nonlinearity was the action of the Lorentz force of the dynamo generated
magnetic field on the solar angular velocity.
  Here we make a detailed study of the robustness of this model with respect to
plausible changes to its main ingredients, including changes to the alpha and
eta profiles as well as the inclusion of a nonlinear alpha quenching. We find
that spatiotemporal fragmentation is present in this model for different
choices of the rotation data and as the details of the model are varied. Taken
together, these results give strong support to the idea that spatiotemporal
fragmentation is likely to occur in general dynamo settings.
