On the origin of the double cell meridional circulation in the solar convection zone

Abstract

Recent advances in helioseismology, numerical simulations and mean-field theory of solar differential rotation have shown that the meridional circulation pattern may consist of two or more cells in each hemisphere of the convection zone. According to the mean-field theory the double-cell circulation pattern can result from the sign inversion of a nondiffusive part of the radial angular momentum transport (the so-called $\Lambda$-effect) in the lower part of the solar convection zone. Here, we show that this phenomenon {can result} from the radial inhomogeneity of the Coriolis number, which depends on the convective turnover time. We demonstrate that if this effect is taken into account then the solar-like differential rotation and the double-cell meridional circulation are both reproduced by the mean-field model. The model is consistent with the distribution of turbulent velocity correlations determined from observations by tracing motions of sunspots and large-scale magnetic fields, indicating that these tracers are rooted just below the shear layer.

22 pages, 6 figures, accepted in ApJ

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• Effects of Emerging Bipolar Magnetic Regions in Mean-field Dynamo Model of Solar Cycles 23 and 24
• Solar dynamo cycle variations with a rotational period
• Nonkinematic solar dynamo models with double-cell meridional circulation
• Comparison of solar activity proxies: eigen vectors versus averaged sunspot numbers
• Effects of small-scale dynamo and compressibility on the $\Lambda$ effect
• Forward Modeling Helioseismic Signatures of One- and Two-cell Meridional Circulation
• Global simulations of stellar dynamos
• Constraining Global Solar Models through Helioseismic Analysis