The case for a distributed solar dynamo shaped by near-surface shear

Abstract

Arguments for and against the widely accepted picture of a solar dynamo being seated in the tachocline are reviewed and alternative ideas concerning dynamos operating in the bulk of the convection zone, or perhaps even in the near-surface shear layer, are discussed. Based on the angular velocities of magnetic tracers it is argued that the observations are compatible with a distributed dynamo that may be strongly shaped by the near-surface shear layer. Direct simulations of dynamo action in a slab with turbulence and shear are presented to discuss filling factor and tilt angles of bipolar regions in such a model.

10 pages, 6 figures, Astrophys. J. 625 (scheduled for the 1 June 2005 issue)

References in corpus (5)

• Simulations of nonhelical hydromagnetic turbulence
• On magnetic field generation in Kolmogorov turbulence
• Nonlinear current helicity fluxes in turbulent dynamos and alpha quenching
• Catastrophic alpha quenching alleviated by helicity flux and shear
• The problem of small and large scale fields in the solar dynamo

Cited by in corpus (15)

• Magnetic field generation in fully convective rotating spheres
• Large-scale dynamos in turbulent convection with shear
• Generation of Magnetic Field by Combined Action of Turbulence and Shear
• Minimal tau approximation and simulations of the alpha effect
• Magnetic fluctuations and formation of large-scale inhomogeneous magnetic structures in a turbulent convection
• Strong mean field dynamos require supercritical helicity fluxes
• Numerical experiments on dynamo action in sheared and rotating turbulence
• Destabilisation of hydrodynamically stable rotation laws by azimuthal magnetic fields
• Shear-current effect in a turbulent convection with a large-scale shear
• Modeling a Maunder Minimum
• The role of diffusivity quenching in flux-transport dynamo models
• The dual role of shear in large-scale dynamos
• A dynamo model for axisymmetric and non-axisymmetric solar magnetic fields
• Toward Coupling Flow Driven and Magnetically Driven Dynamos
• The solar interior - radial structure, rotation, solar activity cycle