Can the long-term hemispheric asymmetry of solar activity result from fluctuations in dynamo parameters?

Abstract

The hemispheric asymmetry of sunspot activity observed possesses a regular component varying on a time scale of several solar cycles whose origin and properties are currently debated. This paper addresses the question of whether the long-term hemispheric asymmetry can result from random variations of solar dynamo parameters in time and latitude. Scatter in the observed tilt angles of sunspot groups is estimated to infer constraints on fluctuations in the dynamo mechanism for poloidal field regeneration. A dynamo model with fluctuations in the Babcock-Leighton type $\alpha$-effect is designed in accordance with these constraints and then used to compute a large number of magnetic cycles for statistical analyses of their hemispheric asymmetry. Hemispheric asymmetry in the simulated dynamo results from the presence of an equator-symmetric part in the oscillating magnetic field. The subdominant quadrupolar oscillations are stochastically forced by dominant dipolar oscillations via the equator-symmetric part of the fluctuating $\alpha$-effect. The amplitude and sense of the asymmetry of individual cycles varies on a time scale of the order of four dynamo-cycle periods. The variations are irregular, i.e. not periodic. The model suggests that asymmetry in the polar magnetic fields in the solar minima can be used as a precursor for asymmetry of sunspot activity in the following solar cycle.

arXiv commentAccepted to A&A, 7 two-column pages, 8 figures

References in corpus (27)

• Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars
• Predicting solar cycle 24 with a solar dynamo model
• Effects of the scatter in sunspot group tilt angles on the large-scale magnetic field at the solar surface
• An Incoherent $\alpha -\Omega$ Dynamo in Accretion Disks
• Meridional circulation in the solar convection zone: time-distance helioseismic inferences from four years of HMI/SDO observations
• Magnetoconvection and dynamo coefficients: II. Field-direction dependent pumping of magnetic field
• A Solar Dynamo Model Driven by Mean-Field Alpha and Babcock-Leighton Sources: Fluctuations, Grand-Minima-Maxima and Hemispheric Asymmetry in Sunspot Cycles
• Differential rotation of main-sequence dwarfs and its dynamo-efficiency
• Turbulent magnetic pumping in a Babcock-Leighton solar dynamo model
• The north-south asymmetry of soft X-ray flare index during solar cycles 21, 22 and 23
• Hemispheric Coupling: Comparing Dynamo Simulations and Observations
• Modeling Solar Cycles 15 to 21 Using a Flux Transport Dynamo
• Hemispheric Asymmetries of Solar Photospheric Magnetism: Radiative, Particulate, and Heliospheric Impacts
• Magnetic Evolution and the Disappearance of Sun-like Activity Cycles
• Grand Minima and North-South Asymmetry of Solar Activity
• Double-peaks of the solar cycle: An explanation from a dynamo model
• Origin of the hemispheric asymmetry of solar activity
• Kodaikanal Digitized White-light Data Archive (1921-2011): Analysis of various solar cycle features
• Comparison of Debrecen and Mount Wilson/Kodaikanal sunspot group tilt angles and the Joy's law
• Fluctuations in the Alpha-Effect and Grand Solar Minima
• Solar dynamo models with alpha-effect and turbulent pumping from local 3D convection calculations
• How supercritical are stellar dynamos, or why do old main-sequence dwarfs not obey gyrochronology?
• Modelling variability of solar activity cycles
• Helioseismic inversion to infer depth profile of solar meridional flow using spherical Born kernels
• Digitized archive of the Kodaikanal images: Representative results of solar cycle variation from sunspot area determination
• Simulation Study of Hemispheric Phase-Asymmetry in the Solar Cycle
• A joined model for solar dynamo and differential rotation

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• Is the Hemispheric Asymmetry of Monthly Sunspot Area an Irregular Process with Long-Term Memory?
• Dynamo Model for North-South Asymmetry of Solar Activity
• North-South Asymmetry in Solar Activity and Solar Cycle Prediction, V: Prediction for the North-South Asymmetry in the Amplitude of Solar Cycle 25
• Long-term Periodicities in North-South Asymmetry of Solar Activity and Alignments of the Giant Planets
• Hemispheric analysis of the magnetic flux in regular and irregular solar active regions
• Inferring Quadrupolar Dynamo Mode from Sunspot Statistics