Nonkinematic solar dynamo models with double-cell meridional circulation

Пипин, В. В.

doi:10.1016/j.jastp.2018.07.010

Cited by 15 publications

(14 citation statements)

References 77 publications

(154 reference statements)

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“…The equatorial drift of the toroidal magnetic field in the subsurface shear layer, i.e. above 0.9R, is provided by the Parker-Yoshimura law (Yoshimura 1975) and the latitudinal turbulent pumping; see the detailed discussion of these effects in Pipin (2018). Similar mechanisms are also suggested by direct numerical simulations, e.g.…”

Section: Dynamo Modelsupporting

confidence: 53%

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The origin and effect of hemispheric helicity imbalance in solar dynamo

et al. 2020

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In this paper we study the effects of the net magnetic helicity density on the hemispheric symmetry of the dynamo generated large-scale magnetic field. Our study employs the axisymmetric dynamo model which takes into account the nonlinear effect of magnetic helicity conservation. We find that, on the surface, the net magnetic helicity follows the evolution of the parity of the large-scale magnetic field. Random fluctuations of the $\unicode[STIX]{x1D6FC}$ -effect and the helicity fluxes can invert the causal relationship, i.e. the net magnetic helicity or the imbalance of magnetic helicity fluxes can drive the magnetic parity breaking. We also found that evolution of the net magnetic helicity of the small-scale fields follows the evolution of the net magnetic helicity of the large-scale fields with some time lag. We interpret this as an effect of the difference of the magnetic helicity fluxes out of the Sun from the large and small scales.

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Section: Dynamo Modelsupporting

confidence: 53%

“…In this paper we will discuss the kinematic version of the mean-field dynamo model developed recently by Pipin (2018) and . We study the mean-field induction equation in a turbulent perfectly conducting medium…”

Section: Dynamo Modelmentioning

confidence: 99%

The origin and effect of hemispheric helicity imbalance in solar dynamo

et al. 2020

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“…The non-axisymmetrical flows (which reflects the North-South asymmetry of magnetic field) obtained from local helioseismology data showed that the symmetrical component is dominant (Kosovichev & Zhao 2016). The asymmetry can be explained by fluctuations of the dynamo α-effect (Pipin 2018). Apparently, the zonal flows of Cycle 24 at high latitudes are substantially weaker than the flows of Cycle 23, and this corresponds to the weaker magnetic activity in Cycle 24 (Howe et al 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Details of this process are still unclear. Recent results of direct numerical simulations (Warnecke et al 2018) and the non-kinematic dynamo model (Pipin 2018) suggest that the diffusive dynamo wave migration proceeds with the help of turbulent pumping. The emerging toroidal magnetic field forms active regions.…”

Section: Discussion: Solar Dynamo Scenariomentioning

confidence: 99%

Dynamo Wave Patterns inside of the Sun Revealed by Torsional Oscillations

Kosovichev

Пипин

2019

ApJL

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Torsional oscillations represent bands of fast and slow zonal flows around the Sun, which extend deep into the convection zone and migrate during solar cycles towards the equator following the sunspot butterfly diagram. Analysis of helioseismology data obtained in 1996-2018 for almost two solar cycles reveals zones of deceleration of the torsional oscillations inside the Sun due to dynamo-generated magnetic field. The zonal deceleration originates near the bottom of the convection zone at high latitudes, and migrates to the surface revealing patterns of magnetic dynamo waves predicted by the Parker's dynamo theory. The analysis reveals that the primary seat of the solar dynamo is located in a high-latitude zone of the tachocline. It suggests a dynamo scenario that can explain 'extended solar cycles' previously observed in the evolving shape of the solar corona. The results show a substantial decrease of the zonal acceleration in the current solar cycle and indicate further decline of activity in the next solar cycle. Although the relationship between the magnitude of zonal deceleration and the amount of emerged toroidal field that leads to formation of sunspots is not yet established, the results open a new perspective for solar cycle modeling and prediction using helioseismology data.

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“…are given in Pipin (2018). Their radial profiles depend on the mean density stratification, profile of the convective RMS velocity uc and on the Coriolis number Ω * = 2Ω0τc, where the Ω0 is the angular velocity of the star and τc is the convective turnover time.…”

Section: Dynamo Modelmentioning

confidence: 99%

On effects of surface bipolar magnetic regions on the convection zone dynamo

Pipin

2021

Preprint

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We investigate the effect of the surface tilted bipolar magnetic regions (BMR) on the large-scale dynamo distributed in the bulk of the convection zone. The study employs the nonlinear 3D mean-field dynamo model. The emergence of the BMR on the surface is modeled by means of the nonaxisymmetric magnetic buoyancy effect which acts on the large-scale toroidal magnetic field in the upper half of the convection zone. The nonaxisymmetric magnetic field which results from this mechanism is shallow. At the surface the effect of the BMR on the magnetic field generation is dominant. However, because of the shallow BMR distribution, its effect on the global dynamo is moderate. The most dynamo effect of the surface BMR is due to their evolution and the convective zone α effect. The fluctuations of the BMR's tilt affect the equatorial symmetry of the dynamo-generated magnetic field. In agreement with the solar observations, the emerging BMRs result in the negative magnetic helicity density of the large-scale nonaxisymmetric magnetic fields in the northern hemisphere of the star.

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Nonkinematic solar dynamo models with double-cell meridional circulation

Cited by 15 publications

References 77 publications

The origin and effect of hemispheric helicity imbalance in solar dynamo

The origin and effect of hemispheric helicity imbalance in solar dynamo

Dynamo Wave Patterns inside of the Sun Revealed by Torsional Oscillations

On effects of surface bipolar magnetic regions on the convection zone dynamo

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