Polar cap magnetic field reversals during solar grand minima: could pores play a role?

Švanda, Michal; Brun, Allan Sacha; Roudier, T.; Jouve, L.

doi:10.1051/0004-6361/201527314

Cited by 6 publications

(4 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, some previous studies indicate that even if there are no sunspots during grand minima, there are still many ephemeral regions at the solar surface which obey the Hale's polarity law. These ephemeral regions may contribute to the poloidal-fieldgeneration mechanism during this time (Priest 2014;Švanda et al 2016;Karak & Miesch 2018). Therefore, we also added an extra Babcock-Leighton source term due to ephemeral regions which acts on the weak magnetic field regime; see Appendix A for details of the Babcock-Leighton source terms.…”

Section: Modelmentioning

confidence: 99%

See 1 more Smart Citation

Does the mean-fieldαeffect have any impact on the memory of the solar cycle?

Hazra

Brun

Nandy

2020

A&A

Self Cite

View full text Add to dashboard Cite

Context. Predictions of solar cycle 24 obtained from advection-dominated and diffusion-dominated kinematic dynamo models are different if the Babcock–Leighton mechanism is the only source of the poloidal field. Some previous studies argue that the discrepancy arises due to different memories of the solar dynamo for advection- and diffusion-dominated solar convection zones. Aims. We aim to investigate the differences in solar cycle memory obtained from advection-dominated and diffusion-dominated kinematic solar dynamo models. Specifically, we explore whether inclusion of Parker’s mean-field α effect, in addition to the Babcock–Leighton mechanism, has any impact on the memory of the solar cycle. Methods. We used a kinematic flux transport solar dynamo model where poloidal field generation takes place due to both the Babcock–Leighton mechanism and the mean-field α effect. We additionally considered stochastic fluctuations in this model and explored cycle-to-cycle correlations between the polar field at minima and toroidal field at cycle maxima. Results. Solar dynamo memory is always limited to only one cycle in diffusion-dominated dynamo regimes while in advection-dominated regimes the memory is distributed over a few solar cycles. However, the addition of a mean-field α effect reduces the memory of the solar dynamo to within one cycle in the advection-dominated dynamo regime when there are no fluctuations in the mean-field α effect. When fluctuations are introduced in the mean-field poloidal source a more complex scenario is evident, with very weak but significant correlations emerging across a few cycles. Conclusions. Our results imply that inclusion of a mean-field α effect in the framework of a flux transport Babcock–Leighton dynamo model leads to additional complexities that may impact memory and predictability of predictive dynamo models of the solar cycle.

show abstract

Section: Modelmentioning

confidence: 99%

“…A = 0 and B = 0). We assume that there is only the radial component of the solar magnetic field at the surface, which is necessary for stress balance between the subsurface and coronal magnetic fields (van Ballegooijen & Mackay 2007). We set B = 0 and ∂(rA)/∂r = 0 as a top boundary condition at the surface (r = R ).…”

Section: Modelmentioning

confidence: 99%

Does the mean-fieldαeffect have any impact on the memory of the solar cycle?

Hazra

Brun

Nandy

2020

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, some previous studies indicate that even if there is no sunspot during grand minima, there are still many ephemeral regions at the solar surface which obey the Hale's polarity law. These ephemeral regions may contribute to the poloidal field generation mechanism during this time (Priest 2014;Švanda et al 2016;Karak & Miesch 2018). Thus, we also added an extra Babcock-Leighton source term due to ephemeral regions which acts on the weak magnetic field regime.…”

Section: Recent Helioseismic Resultsmentioning

confidence: 99%

Does the mean-field alpha effect have any impact on the memory of the solar cycle?

Hazra,

Brun,

Nandy

2020

Preprint

Self Cite

View full text Add to dashboard Cite

Context. Predictions of solar cycle 24 obtained from the advection-dominated and diffusion-dominated kinematic dynamo model are different if we consider only the Babcock-Leighton mechanism as a poloidal field generation source term. Yeates et al. (2008) argue that the discrepancy between the results is due to the different memory of solar dynamo for advection-and diffusion-dominated solar convection zones. Aims. We aim to investigate the discrepancy between the solar cycle memory obtained from advection-dominated and diffusiondominated kinematic solar dynamo models. Specifically, we want to investigate whether another poloidal field generation mechanism, namely, Parker's mean-field alpha effect has any impact on the memory of the solar cycle. Methods. We used a kinematic flux transport solar dynamo model where poloidal field generation takes place due to both the Babcock-Leighton mechanism and mean-field alpha effect. Results. The addition of a mean-field alpha effect reduces the memory of the Babcock Leighton solar dynamo to within one cycle for both advection-and diffusion-dominated dynamo regimes. Our result provides an alternative resolution to the discrepancy in memory of advection-and diffusion-dominated kinematic dynamo models. We also find a moderate decrease in the correlation between the radial flux at the cycle minima and the toroidal flux at the maxima of the next cycle with the increase of mean-field alpha amplitude. Conclusions. We confirm the conclusions of Yeates et al. (2008) and Karak and Nandy (2012) regarding the short, one-cycle memory of the solar cycle. We establish that the mean-field alpha effect impacts the memory of the solar cycle. However, correlation coefficients are highly dependent on the assumed amplitude and fluctuation levels of the mean-field alpha.

show abstract

“…An example is e.g. Svanda et al (2016) where the researchers investigated the contribution of the magnetic flux carried by pores to the reversal of the global magnetic field of the Sun. Nonetheless, such image processing is not the focus of the present work.…”

Section: Observations and Datamentioning

confidence: 99%

Prediction of the amplitude of solar cycle 25 using polar faculae observations

Janssens

2021

J. Space Weather Space Clim.

View full text Add to dashboard Cite

Based on the monthly number of polar faculae, a forecast of the amplitude of solar cycle 25 (SC25) is provided, as well as a prediction of the number of solar flares. Faculae near both solar poles have been visually observed using a commercial off-the-shelf 20 cm Schmidt-Cassegrain telescope since 1995. The monthly averages were corrected for varying seeing conditions and the heliographic latitude of the center of the solar disk B0. From the deduced relationship between the smoothed number of monthly polar faculae during the solar cycle minimum, and the subsequent maximum of the monthly sunspot number, a prediction has been made for the amplitude of the next solar cycle. The methodology used can be considered as a precursor technique. The expected number of M- and X-class flares was calculated based on a statistical approach. The maximum of SC25 is predicted to be 118 ± 29, of similar strength than the previous SC24. Also the number of M5 or stronger flares is expected to be comparable to that of the previous solar cycle.

show abstract

Polar cap magnetic field reversals during solar grand minima: could pores play a role?

Cited by 6 publications

References 52 publications

Does the mean-fieldαeffect have any impact on the memory of the solar cycle?

Does the mean-fieldαeffect have any impact on the memory of the solar cycle?

Does the mean-field alpha effect have any impact on the memory of the solar cycle?

Prediction of the amplitude of solar cycle 25 using polar faculae observations

Contact Info

Product

Resources

About