Double-peaks of the solar cycle: An explanation from a dynamo model

Abstract

One peculiar feature of the solar cycle which is yet to be understood properly is the frequent occurrence of double peaks (also known as the Gnevyshev peaks). Not only the double peaks but also multiple peaks and spikes are often observed in any phase of the cycle. We propose that these peaks and spikes are generated due to fluctuations in the Babcock-Leighton process (the poloidal field generation from tilted bipolar magnetic regions). When the polar field develops, large negative fluctuations in the Babcock-Leighton process can reduce the net polar field abruptly. As these fluctuations in the polar field are propagated to the new toroidal field, these can promote double peaks in the next solar cycle. When fluctuations in the polar field occur outside the solar maximum, we observe their effects as spikes or dips in the following sunspot cycle. Using an axisymmetric Babcock-Leighton dynamo model we first demonstrate this idea. Later, we perform a long simulation by including random scatter in the poloidal field generation process and successfully reproduce the double-peaked solar cycles. These results are robust under reasonable changes in the model parameters as long as the diffusivity is not too larger than $10^{12}$ cm${}^2$s${}^{-1}$. Finally, we analyze the observed polar field data to show a close connection between the short-term fluctuations in the polar field and the double peaks/spikes in the next cycle. Thereby, this supports our theoretical idea that the fluctuations in the Babcock-Leighton process can be responsible for the double peaks/spikes in the observed solar cycle.

arXiv comment12 pages including 5 figures. Accepted in ApJ

References in corpus (32)

• Predicting solar cycle 24 with a solar dynamo model
• Sunspot group tilt angles and the strength of the solar cycle
• Full--Sphere Simulations of a Circulation--Dominated Solar Dynamo: Exploring the Parity Issue
• Exploring the Physical Basis of Solar Cycle Predictions: Flux Transport Dynamics and Persistence of Memory in Advection versus Diffusion Dominated Solar Convection Zones
• The crucial role of surface magnetic fields for the solar dynamo
• Bipolar Magnetic Regions on the Sun: Global Analysis of the SOHO/MDI Data Set
• Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies
• Effects of the scatter in sunspot group tilt angles on the large-scale magnetic field at the solar surface
• Magnetic Rossby waves in the solar tachocline and Rieger-type periodicities
• Calibrating 100 Years of Polar Faculae Measurements: Implications for the Evolution of the Heliospheric Magnetic Field
• The cause of the weak solar cycle 24
• Solar-Cycle Characteristics Examined in Separate Hemispheres: Phase, Gnevyshev Gap, and Length of Minimum
• Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock--Leighton Solar Dynamo Model
• The Effect of "Rogue" Active Regions on the Solar Cycle
• Limits to solar cycle predictability: Cross-equatorial flux plumes
• A 3D Babcock-Leighton Solar Dynamo Model
• On the Connection between Mean Field Dynamo Theory and Flux Tubes
• Does the Babcock--Leighton Mechanism Operate on the Sun?
• Turbulent Pumping of Magnetic Flux Reduces Solar Cycle Memory and thus Impacts Predictability of the Sun's Activity
• The Waldmeier effect and the flux transport solar dynamo
• A coupled $2\times 2$D Babcock-Leighton solar dynamo model. II. Reference dynamo solutions
• Babcock-Leighton solar dynamo: the role of downward pumping and the equatorward propagation of activity
• A possible explanation of the Maunder minimum from a flux transport dynamo model
• Re-examining Sunspot Tilt Angle to Include Anti-Hale Statistics
• Polar Network Index as a magnetic proxy for the solar cycle studies
• Kodaikanal Digitized White-light Data Archive (1921-2011): Analysis of various solar cycle features
• Equatorial magnetohydrodynamic shallow water waves in the solar tachocline
• A theoretical study of the build-up of the Sun's polar magnetic field by using a 3D kinematic dynamo model
• Recovery from Maunder-like Grand Minima in a Babcock--Leighton Solar Dynamo Model
• Tilt Angle and Footpoint Separation of Small and Large Bipolar Sunspot Regions Observed with HMI
• Sunspot areas and tilt angles for solar cycles 7-10
• Diamagnetic pumping in a rotating convection zone

Cited by in corpus (23)

• A model of a tidally synchronized solar dynamo
• Models for the long-term variations of solar activity
• Long-term modulation of solar cycles
• Physical Models for Solar Cycle Predictions
• The polar precursor method for solar cycle prediction: comparison of predictors and their temporal range
• Dynamo saturation through the latitudinal variation of bipolar magnetic regions in the Sun
• Shaken and stirred: When Bond meets Suess-de Vries and Gnevyshev-Ohl
• Physical link of the polar field build-up with the Waldmeier effect broadens the scope of early solar cycle prediction: Cycle 25 is likely to be slightly stronger than Cycle 24
• Stellar Dynamos with Solar and Anti-solar Differential Rotations: Implications to Magnetic Cycles of Slowly Rotating Stars
• Is the Hemispheric Asymmetry of Monthly Sunspot Area an Irregular Process with Long-Term Memory?
• Dynamo Model for North-South Asymmetry of Solar Activity
• Toroidal flux loss due to flux emergence explains why solar cycles rise differently but decay in a similar way
• Can the long-term hemispheric asymmetry of solar activity result from fluctuations in dynamo parameters?
• Supercriticality of the dynamo limits the memory of the polar field to one cycle
• Magnetic fluxes of solar active regions of different magneto-morphological classes: I. Cyclic variations
• Probing the variations in the timing of the Sun's polar magnetic field reversals through observations and surface flux transport simulations
• Coronal magnetic field evolution over the cycle 24
• Hemispheric analysis of the magnetic flux in regular and irregular solar active regions
• Inferring Quadrupolar Dynamo Mode from Sunspot Statistics
• Temporal and Latitudinal Variation in Penumbra-Umbra Ratios of the Sunspots: Analyses of RGO, Kodaikanal and Debrecen Databases
• Solar Cycle Prediction: Challenges, Progress, and Future Perspectives
• Evolution of the Sun's activity and the poleward transport of remnant magnetic flux in Cycles 21--24
• Stellar cycle variability in Mount Wilson stars and dynamo models: Rotation rate and dynamo number dependency