Abstract
We present a 3D kinematic solar dynamo model in which poloidal field is
generated by the emergence and dispersal of tilted sunspot pairs (more
generally Bipolar Magnetic Regions, or BMRs). The axisymmetric component of
this model functions similarly to previous 2D Babcock-Leighton (BL) dynamo
models that employ a double-ring prescription for poloidal field generation but
we generalize this prescription into a 3D flux emergence algorithm that places
BMRs on the surface in response to the dynamo-generated toroidal field. In this
way, the model can be regarded as a unification of BL dynamo models (2D in
radius/latitude) and surface flux transport models (2D in latitude/longitude)
into a more self-consistent framework that captures the full 3D structure of
the evolving magnetic field. The model reproduces some basic features of the
solar cycle including an 11-yr periodicity, equatorward migration of toroidal
flux in the deep convection zone, and poleward propagation of poloidal flux at
the surface. The poleward-propagating surface flux originates as trailing flux
in BMRs, migrates poleward in multiple non-axisymmetric streams (made
axisymmetric by differential rotation and turbulent diffusion), and eventually
reverses the polar field, thus sustaining the dynamo. In this letter we briefly
describe the model, initial results, and future plans.
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