Mean-field solar dynamo models with strong meridional flow at the bottom of the convection zone

Abstract

The paper presents a study of kinematic axisymmetric mean-field dynamo models for a case of the meridional circulation with a deep-seated stagnation point and a strong return flow at the bottom of the convection zone. This kind of circulation follows from mean-field models of the angular momentum balance in the solar convection zone. We show that it is possible for this types of meridional circulation to construct kinematic dynamo models that resemble in some aspects the sunspot magnetic activity cycle. The dynamo model includes turbulent sources of the large-scale poloidal magnetic field production, due to kinetic helicity and a combined effect due to Coriolis force and the large-scale current. In these models the toroidal magnetic field, which is responsible for the sunspot production, is concentrated at the bottom of the convection zone, and is transported to low-latitude regions by the meridional flow. The meridional component of the poloidal field is also concentrated at the bottom of the convection zone while the radial component is concentrated in near polar regions. There are some issues which, perhaps, are resulted from the given meridional circulation pattern and the distribution of the magnetic diffusivity inside convection zone. In particular, in the near-equatorial regions the phase relations between the toroidal and poloidal components disagree with observations. Also, we show that the period of the magnetic cycle may not always monotonically decrease with the increase of the meridional flow speed. Thus, for the further progress it is important to determine the structure of the meridional circulation, which is one of the critical properties, from helioseismology observations.

References in corpus (5)

• Solar differential rotation and meridional flow: The role of a subadiabatic tachocline for the Taylor-Proudman balance
• Flux-transport dynamos with Lorentz force feedback on differential rotation and meridional flow: Saturation mechanism and torsional oscillations
• The mean electro-motive force, current- and cross-helicity under the influence of rotation, magnetic field and shear
• Stellar dynamos with $\vec{\Omega }\times \vec{J}$ effect
• Flux-dominated solar dynamo model with a thin shear layer

Cited by in corpus (15)

• Evolution of solar and stellar dynamo theory
• A new dynamo pattern revealed by the tilt angle of bipolar sunspot groups
• The mean-field solar dynamo with double cell meridional circulation pattern
• Helicity conservation in nonlinear mean-field solar dynamo
• The origin of the helicity hemispheric sign rule reversals in the mean-field solar-type dynamo
• Effects of turbulent pumping on stellar activity cycles
• The dynamics of Wolf numbers based on nonlinear dynamo with magnetic helicity: comparisons with observations
• Dynamics on Berkovich spaces in low dimensions
• Observing dynamos in cool stars
• Solar Dynamo and Toroidal Field Instabilities
• Magnetic fields in circumstellar envelopes of evolved AGB stars
• An overshoot solar dynamo with a strong return meridional flow
• Solar differential rotation: origin, models, and implications for dynamo
• Helicity-vorticity turbulent pumping of magnetic fields in solar convection zone
• Advances in mean-field dynamo theories