Numerical modeling of magnetic self-organization at the top of the solar convection zone

Nonlinear, numerical computation with the NIMROD code is used to explore magnetic self-organization at the top of the solar convection zone. When considered together, two related effects (localized convective turbulence and rotational induction) create a robust mechanism for magnetic field generation, regardless of its magnitude. In the vicinity of the thin, shallow superadiabatic layer, convective turbulence and subsequent magnetic self-organization generate a radially-localized, latitudinally-elongated magnetic structure. The convective turbulence drive is stabilized by magnetic field. While this limits the achievable magnetic field from localized turbulence alone, the resulting structure is self-healing: should any part of the magnetic structure be perturbed away, the localized convective turbulence will rapidly regenerate it. Differential rotation of the sun creates an inductive electric field which also causes growth of the magnetic field within the structure, the rate of which scales with its magnitude. The nonlinear evolution of such a shallow magnetic structure may be able to explain some key surface magnetic features, including the behavior of sunspots, granules, etc.