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Is a deep one-cell meridional circulation essential for the flux transport Solar Dynamo?
Solar and Stellar Astrophysics · Submitted 11 Sep 2013
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim As long as there is an equatorward flow in low latitudes at the bottom of the convection zone, we find that the solar behavior is approximately reproduced.
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The abstract, sentence by sentence
The solar activity cycle is successfully modeled by the flux transport dynamo, in which the meridional circulation of the Sun plays an important role. Most of the kinematic dynamo simulations assume a one-cell structure of the meridional circulation within the convection zone, with the equatorward return flow at its bottom. In view of the recent claims that the return flow occurs at a much shallower depth, we explore whether a meridional circulation with such a shallow return flow can still retain the attractive features of the flux transport dynamo (such as a proper butterfly diagram, the proper phase relation between the toroidal and poloidal fields). We consider additional cells of the meridional circulation below the shallow return flow---both the case of multiple cells radially stacked above one another and the case of more complicated cell patterns. As long as there is an equatorward flow in low latitudes at the bottom of the convection zone, we find that the solar behavior is approximately reproduced. However, if there is either no flow or a poleward flow at the bottom of the convection zone, then we cannot reproduce solar behavior. On making the turbulent diffusivity low, we still find periodic behavior, although the period of the cycle becomes unrealistically large. Also, with a low diffusivity, we do not get the observed correlation between the polar field at the sunspot minimum and the strength of the next cycle, which is reproduced when diffusivity is high. On introducing radially downward pumping, we get a more reasonable period and more solar-like behavior even with low diffusivity.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The solar activity cycle is successfully modeled by the flux transport dynamo, in which the meridional circulation of the Sun plays an important role. | background 1.00 | 0.05 | 0.03 | asserted 1.00 |
| s1 | Most of the kinematic dynamo simulations assume a one-cell structure of the meridional circulation within the convection zone, with the equatorward return flow at its bottom. | background 1.00 | 0.04 | 0.02 | asserted 1.00 |
| s2 | In view of the recent claims that the return flow occurs at a much shallower depth, we explore whether a meridional circulation with such a shallow return flow can still retain the attractive features of the flux transport dynamo (such as a proper butterfly diagram, the proper phase relation between the toroidal and poloidal fields). | contribution 0.59 | 0.14 | 0.03 | hedged possibility 0.46 |
| s3 | We consider additional cells of the meridional circulation below the shallow return flow---both the case of multiple cells radially stacked above one another and the case of more complicated cell patterns. | method 0.57 | 0.76 | 0.03 | unclear 0.55 |
| s4 | As long as there is an equatorward flow in low latitudes at the bottom of the convection zone, we find that the solar behavior is approximately reproduced. | result 0.99 | 0.95 | 0.78 | asserted 1.00 |
| s5 | However, if there is either no flow or a poleward flow at the bottom of the convection zone, then we cannot reproduce solar behavior. | result 1.00 | 0.91 | 0.34 | asserted 1.00 |
| s6 | On making the turbulent diffusivity low, we still find periodic behavior, although the period of the cycle becomes unrealistically large. | result 1.00 | 0.93 | 0.04 | asserted 1.00 |
| s7 | Also, with a low diffusivity, we do not get the observed correlation between the polar field at the sunspot minimum and the strength of the next cycle, which is reproduced when diffusivity is high. | result 1.00 | 0.90 | 0.04 | asserted 1.00 |
| s8 | On introducing radially downward pumping, we get a more reasonable period and more solar-like behavior even with low diffusivity. | result 1.00 | 0.92 | 0.08 | asserted 1.00 |
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The paper
Original abstract
The solar activity cycle is successfully modeled by the flux transport dynamo, in which the meridional circulation of the Sun plays an important role. Most of the kinematic dynamo simulations assume a one-cell structure of the meridional circulation within the convection zone, with the equatorward return flow at its bottom. In view of the recent claims that the return flow occurs at a much shallower depth, we explore whether a meridional circulation with such a shallow return flow can still retain the attractive features of the flux transport dynamo (such as a proper butterfly diagram, the proper phase relation between the toroidal and poloidal fields). We consider additional cells of the meridional circulation below the shallow return flow---both the case of multiple cells radially stacked above one another and the case of more complicated cell patterns. As long as there is an equatorward flow in low latitudes at the bottom of the convection zone, we find that the solar behavior is approximately reproduced. However, if there is either no flow or a poleward flow at the bottom of the convection zone, then we cannot reproduce solar behavior. On making the turbulent diffusivity low, we still find periodic behavior, although the period of the cycle becomes unrealistically large. Also, with a low diffusivity, we do not get the observed correlation between the polar field at the sunspot minimum and the strength of the next cycle, which is reproduced when diffusivity is high. On introducing radially downward pumping, we get a more reasonable period and more solar-like behavior even with low diffusivity.
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References
How the literature uses it
6 arXiv papers cite this in 8 sentences
Papers citing it · 6 sentences without a confident label
Cites it as support 2 papers
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So, when we want to vary our dynamo parameters over a wide range or when we use unusual parameter specifications (such as a multi-cell meridional circulation), we are often unable to obtain results with the local $α$ parameterization procedure and are forced to use the more robust non-local procedure described in 3.1 [ref] .
The treatment of magnetic buoyancy in flux transport dynamo models · Comparison between the non-local and local methods · 0.97
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Subsequent research has shown that under certain circumstances the flux transport paradigm can work even in the presence of complex, multi-cellular meridional flow [ref] .
Mean field models of flux transport dynamo and meridional circulation in the Sun and stars · Modelling the solar cycle: the paradigm shift from the $αΩ$ dynamo to the flux transport dynamo · 0.97
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