The origin of the helicity hemispheric sign rule reversals in the mean-field solar-type dynamo

Пипин, В. В.; Zhang, H.; Sokoloff, Dmitry; Kuzanyan, K. M.; Gao, Yu

doi:10.1093/mnras/stt1465

Cited by 20 publications

(35 citation statements)

References 56 publications

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“…It consists of the magnetic helicity density fluxes which result from the large-scale magnetic dynamo wave evolution. The given contribution alleviates the catastrophic quenching problem [25,71]. Also the catastrophic quenching of the α-effect can be alleviated with help of the diffusive flux of the turbulent magnetic helicity, F χ = −η χ ∇χ [18,10].…”

Section: Dynamo Equationsmentioning

confidence: 99%

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Nonkinematic solar dynamo models with double-cell meridional circulation

Пипин

2018

Journal of Atmospheric and Solar-Terrestrial Physics

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Employing the standard solar interior model as input we construct a dynamically-consistent nonlinear dynamo model that takes into account the detailed description of the Λ-effect, turbulent pumping, magnetic helicity balance, and magnetic feedback on the differential rotation and meridional circulation. The background mean-field hydrodynamic model of the solar convection zone accounts the solar-like angular velocity profile and the double-cell meridional circulation. We investigate an impact of the nonlinear magnetic field generation effects on the long-term variability and properties of the magnetic cycle. The nonlinear dynamo solutions are studied in the wide interval of the α effect parameter from a slightly subcritical to supercritical values. It is found that the magnetic cycle period decreases with the increasing cycle's magnitude. The periodic long-term variations of the magnetic cycle are excited in case of the overcritical α effect. These variations result from the hemispheric magnetic helicity exchange. It depends on the magnetic diffusivity parameter and the magnetic helicity production rate. The large-scale magnetic activity modifies the distribution of the differential rotation and meridional circulation inside convection zone. It is found that the magnetic feedback on the global flow affects the properties of the long-term magnetic cycles. We confront our findings with solar and stellar magnetic activity observations.

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Section: Dynamo Equationsmentioning

confidence: 99%

“…Feasibility of this idea can be questioned both the observational and theoretical arguments [6]. The distributed dynamo models can be constructed with [4,26,56] and without [50,71] effect of meridional transport of the large-scale magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Nonkinematic solar dynamo models with double-cell meridional circulation

Пипин

2018

Journal of Atmospheric and Solar-Terrestrial Physics

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“…Moreover, the reversal sign of helicity in these statistical work has also attracted much attention [84]. The change of magnetic helicity with solar cycles, such as helicity butterfly diagram, also bring some new thoughts on the generations of magnetic fields with the dynamo process in the subatmosphere (such as, Kleeorin et al (2003), Zhang et al (2012), Pipin et al (2013) [85][86][87]).…”

Section: Free Energy Contributed From Non-potential Magnetic Fieldsmentioning

confidence: 99%

From polarimetry to helicity: Studies of solar magnetic fields at the Huairou Solar Observing Station

Zhang¹

2019

Sci. China Phys. Mech. Astron.

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In this paper, we briefly introduce the basic questions in the measurements of solar magnetic fields and the possible error sources due to the approximation of the theory of radiation transfer of spectral lines in the solar atmosphere. We introduce some basic research progress in magnetic field measurement at Huairou Solar Observing Station of National Astronomical Observatories of the Chinese Academy of Sciences, especially concerning the non-potentiality in solar active regions, such as the magnetic shear, current and helicity. We also discuss some basic questions for the measurements of the magnetic fields and corresponding challenges for the future studies. Solar spectrum, Polarization -Stokes parameters, Magnetic fields -current and helicity PACS number(s): Citation: Hongqi Zhang, From Polarimetry to Helicity, Sci. China-Phys. Mech. Astron. , (), doi:

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“…Other predictions of mean-field dynamo models include the existence of polar and equatorial branches in the timelatitude diagram of magnetic helicity evolution. According to Pipin et al (2013), those branches represent the transport of magnetic helicity flux to the polar regions, both on large and small scales. In this paper we present the first observational evidence of polar branches of the large-scale magnetic helicity in solar cycle 24.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Magnetic Helicity in Solar Cycle 24

Пипин

Pevtsov

Liu

et al. 2019

ApJL

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We propose a novel approach to reconstruct the surface magnetic helicity density on the Sun or sun-like stars. The magnetic vector potential is determined via decomposition of vector magnetic field measurements into toroidal and poloidal components. The method is verified using data from a nonaxisymmetric dynamo model. We apply the method to vector field synoptic maps from Helioseismic and Magnetic Imager (HMI) on board of Solar Dynamics Observatory (SDO) to study evolution of the magnetic helicity density during solar cycle 24. It is found that the mean helicity density of the non-axisymmetric magnetic field of the Sun evolves in a way which is similar to that reported for the current helicity density of the solar active regions. It has predominantly the negative sign in the northern hemisphere, and it is positive in the southern hemisphere. Also, the hemispheric helicity rule for the non-axisymmetric magnetic field showed the sign inversion at the end of cycle 24. Evolution of magnetic helicity density of large-scale axisymmetric magnetic field is different from that expected in dynamo theory. On one hand, the mean large-and small-scale components of magnetic helicity density display the hemispheric helicity rule of opposite sign at the beginning of cycle 24. However, later in the cycle, the two helicities exhibit the same sign in contrast with the theoretical expectations.

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The origin of the helicity hemispheric sign rule reversals in the mean-field solar-type dynamo

Cited by 20 publications

References 56 publications

Nonkinematic solar dynamo models with double-cell meridional circulation

Nonkinematic solar dynamo models with double-cell meridional circulation

From polarimetry to helicity: Studies of solar magnetic fields at the Huairou Solar Observing Station

Evolution of Magnetic Helicity in Solar Cycle 24

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