Towards an algebraic method of solar cycle prediction

Nagy, Melinda; Petrovay, K.; Lemerle, Alexandre; Charbonneau, Paul

doi:10.1051/swsc/2020051

Cited by 7 publications

(8 citation statements)

References 24 publications

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“…Our results align with the findings of Nagy et al (2020) and Whitbread et al (2018), but our study requires a smaller number of ARs, approximately 500 ARs compared to their 750 ARs. These studies reveal that while several rogue ARs can induce noticeable variations in the solar polar field, the collective impact of numerous ARs with smaller contributions to the polar field cannot be disregarded.…”

Section: Impact Of Ars With Small D F On the Cumulative Final Dipole ...supporting

confidence: 91%

Toward a Live Homogeneous Database of Solar Active Regions Based on SOHO/MDI and SDO/HMI Synoptic Magnetograms. II. Parameters for Solar Cycle Variability

Wang,

Jiang,

Luo

2024

ApJ

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Solar active regions (ARs) determine solar polar fields and cause solar cycle variability within the framework of the Babcock–Leighton dynamo. The contribution of an AR to the polar field is measured by its dipole field, which results from flux emergence and subsequent flux transport over the solar surface. The dipole fields contributed by an AR before and after the flux transport are referred to as the initial and final dipole fields, respectively. For a better understanding and prediction of solar cycles, in this paper, we provide a database including AR's initial and final dipole fields and the corresponding results of their bipolar magnetic region (BMR) approximation from 1996 onward. We also identify the repeated ARs and provide the optimized transport parameters. Based on our database, we find that although the commonly used BMR approximation performs well for the initial dipole field, it exhibits a significant deviation for the final dipole field. To accurately assess an AR’s contribution to the polar field, the final dipole field with its real configuration should be applied. Despite the notable contributions of a few rogue ARs, approximately the top 500 ARs ordered by their final dipole fields are necessary to derive the polar field at the cycle minimum. While flux transport may increase or decrease the dipole field for an individual AR, its collective impact over all ARs in a cycle is a reduction in their total dipole field.

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Section: Impact Of Ars With Small D F On the Cumulative Final Dipole ...supporting

confidence: 91%

Toward a Live Homogeneous Database of Solar Active Regions Based on SOHO/MDI and SDO/HMI Synoptic Magnetograms. II. Parameters for Solar Cycle Variability

Wang,

Jiang,

Luo

2024

ApJ

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“…This indicates that detailed knowledge of the structure and evolution of each individual active region may not be indispensable for a tolerably good predictive skill in the algebraic method in most (though not all) cycles. This issue will be discussed further in the second paper of this series (Nagy et al, 2020).…”

Section: Comparison To a Dynamo Model Solutionmentioning

confidence: 93%

Towards an algebraic method of solar cycle prediction

Petrovay

Nagy

Yeates

2020

J. Space Weather Space Clim.

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We discuss the potential use of an algebraic method to compute the value of the solar axial dipole moment at solar minimum, widely considered to be the most reliable precursor of the activity level in the next solar cycle. The method consists of summing up the ultimate contributions of individual active regions to the solar axial dipole moment at the end of the cycle. A potential limitation of the approach is its dependence on the underlying surface flux transport (SFT) model details. We demonstrate by both analytical and numerical methods that the factor relating the initial and ultimate dipole moment contributions of an active region displays a Gaussian dependence on latitude with parameters that only depend on details of the SFT model through the parameter η/ D u where η is supergranular diffusivity and D u is the divergence of the meridional flow on the equator. In a comparison with cycles simulated in the 2x2D dynamo model we further demonstrate that the inaccuracies associated with the algebraic method are minor and the method may be able to reproduce the dipole moment values in a large majority of cycles.

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“…Under such simplification, each tilted BMR, after averaging azimuthally, will appear as a pair of flux rings of opposite polarity with a bipole source having a finite latitudinal separation. This methodology has been utilized earlier (Nagy et al 2020;Petrovay et al 2020;Yeates 2020) Here the variation in number and flux is mentioned as percent number-percent flux. Orange (5%-5%) and dark-orange (10%-5%) curves depict the time evolution of dipole moment, with AH-J regions having 5% flux but 5% and 10% in number, respectively.…”

Section: Effectivity Of Anomalous Regions On Global Dipolementioning

confidence: 99%

Impact of Anomalous Active Regions on the Large-scale Magnetic Field of the Sun

Pal,

Bhowmik,

Mahajan

et al. 2023

ApJ

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One of the major sources of perturbation in the solar cycle amplitude is believed to be the emergence of anomalous active regions that do not obey Hale’s polarity law and Joy’s law of tilt angles. Anomalous regions containing high magnetic flux that disproportionately impact the polar field are sometimes referred to as “rogue regions.” In this study, utilizing a surface flux transport model, we analyze the large-scale dipole moment buildup due to the emergence of anomalous active regions on the solar surface. Although these active regions comprise a small fraction of the total sunspot number, they can substantially influence the magnetic dipole moment buildup and subsequent solar cycle amplitude. Our numerical simulations demonstrate that the impact of “anti-Joy” regions on the solar cycle is similar to those of “anti-Hale” regions. We also find that the emergence time, emergence latitude, relative number, and flux distribution of anomalous regions influence the large-scale magnetic field dynamics in diverse ways. We establish that the results of our numerical study are consistent with the algebraic (analytic) approach to explaining the Sun’s dipole moment evolution. Our results are relevant for understanding how anomalous active regions modulate the Sun’s large-scale dipole moment buildup and its reversal timing within the framework of the Babcock–Leighton dynamo mechanism—now believed to be the primary source of solar cycle variations.

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Towards an algebraic method of solar cycle prediction

Cited by 7 publications

References 24 publications

Toward a Live Homogeneous Database of Solar Active Regions Based on SOHO/MDI and SDO/HMI Synoptic Magnetograms. II. Parameters for Solar Cycle Variability

Toward a Live Homogeneous Database of Solar Active Regions Based on SOHO/MDI and SDO/HMI Synoptic Magnetograms. II. Parameters for Solar Cycle Variability

Towards an algebraic method of solar cycle prediction

Impact of Anomalous Active Regions on the Large-scale Magnetic Field of the Sun

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