Passos, Dario, Charbonneau, Paul and Beaudoin, Patrice (2012), "An Exploration of Non-kinematic Effects in Flux Transport Dynamos", SOLAR PHYSICS, 279, 1: 1-22.
Abstract: Recent global magnetohydrodynamical simulations of solar convection
producing a large-scale magnetic field undergoing regular, solar-like
polarity reversals also present related cyclic modulations of
large-scale flows developing in the convecting layers. Examination of
these simulations reveal that the meridional flow, a crucial element in
flux transport dynamos, is driven at least in part by the Lorentz force
associated with the cycling large-scale magnetic field. This suggests
that the backreaction of the field onto the flow may have a pronounced
influence on the long-term evolution of the dynamo. We explore some of
the associated dynamics using a low-order dynamo model that includes
this Lorentz force feedback. We identify several characteristic
solutions which include single period cycles, period doubling and chaos.
To emulate the role of turbulence in the backreaction process we subject
the model to stochastic fluctuations in the parameter that controls the
Lorentz force amplitude. We find that short term fluctuations produce
long-term modulations of the solar cycle and, in some cases, grand
minima episodes where the amplitude of the magnetic field decays to near
zero. The chain of events that triggers these quiescent phases is
identified. A subsequent analysis of the energy transfer between
large-scale fields and flows in the global magnetohydrodynamical
simulation of solar convection shows that the magnetic field extracts
energy from the solar differential rotation and deposits part of that
energy into the meridional flow. The potential consequences of this
marked departure from the kinematic regime are discussed in the context
of current solar cycle modeling efforts based on flux transport dynamos.
Keywords: Solar cycle: models; Sunspots: magnetic fields; Sunspots: statistics
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