The Case for a Distributed Solar Dynamo Shaped by Near-Surface Shear

By Axel Brandenburg. 2005

335 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/05c2e25da026a77d60097d17c4a61086ef6b873f

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Citations in the corpus

PERSISTENT MAGNETIC WREATHS IN A RAPIDLY ROTATING SUN (2010, background): “Others have suggested that the latitudinal and radial gradients of angular velocity in the bulk of the convection zone may be sufficient for global dynamo action (e.g., Dikpati & Charbonneau 1999; Brandenburg 2005; Guerrero & de Gouveia Dal Pino 2007).”
CYCLIC MAGNETIC ACTIVITY DUE TO TURBULENT CONVECTION IN SPHERICAL WEDGE GEOMETRY (2012, background): “On the other hand, the negative radial differential rotation in the near-surface shear layer (as anticipated by Brandenburg 2005), which is here absent, is not the explanation for the resulting equatorward migraton.”
Magnetic Fields of Nondegenerate Stars (2009, background): “…- was recently invoked and investigated theoretically in the particular case of the Sun as an alternaive to conventional interface dynamo models (Brandenburg 2005); in particular, this new model can potentially solve a number of longstanding issues (e.g., the large number of toroidal flux belts…”
Solar Dynamo Theory (2014, background): “The numerical experiments of Simard et al. (2013) thus support the notion that there may be two large-scale dynamos operating in the Sun (see also Benevolenskaya 1995, 1998; Mason et al. 2002; Brandenburg 2005).”
MAGNETIC WREATHS AND CYCLES IN CONVECTIVE DYNAMOS (2012, background): “The paradigm proposed here may also help address other difficulties with tachocline-based dynamos discussed by Brandenburg (2005).”
BIPOLAR MAGNETIC REGIONS ON THE SUN: GLOBAL ANALYSIS OF THE SOHO/MDI DATA SET (2011, methodology): “Introduction The origin of solar activity with its 11 yr cycle is generally understood in terms of an oscillatory dynamo inside the Sun (cf. Brandenburg & Subramanian 2005; Brandenburg 2005).”
Solar Interior Rotation and its Variation (2009, background): “Some attempts have been made to use the near-surface shear to drive or at least contribute to a solar dynamo, for example by Brandenburg (2005), but Dikpati et al. (2002) showed that any dynamo contribution from the shear of the outer layers could only provide a fraction of the effect needed to…”
Revisiting the Sunspot Number (2014, background): “emes that could be tested against this peculiar evolution of sun, Babcockspots -Leighton near-surface flux diffusion mechanism (MuñozJaramillo et al. 2010, 2011), ole of a nearr -surface shear layer (Brandenburg 2005) or a near-surface magnetic flux aggregation mechanism (Schatten 2009). The selecti”
Magnetic Field Generation in Fully Convective Rotating Spheres (2004, background): “For example, the interpretation of bipolar spots in terms of distinct flux tubes may not be valid and hence the presence of spots may not necessarily indicate a high degree of intermittency in the interior (Brandenburg 2005).”
Astrophysical magnetic fields and nonlinear dynamo theory (2004, background): “The rather unconventional suggestion of a shallow anchoring depth [55] will be addressed further at the end of Section 11.”
The Polarimetric and Helioseismic Imager on Solar Orbiter (2019, background): “Proposals for the location of the dynamo cover the two main radial shear layers, one at the bottom of the convection zone and one near the solar surface (Howe 2009; Brandenburg 2005), cf. Charbonneau (2013).”
Chromospheric Activity in G and K Main-Sequence Stars, and What It Tells Us about Stellar Dynamos (2007, background): “From helioseismology Benevolenskaya et al. (1999) derived that in the Sun the largest gradients in rotation rates are found near the surface and at the bottom of the convective layer, especially at low latitudes (see Brandenburg 2005, Fig.”