New results concerning the global solar cycle

Макаров, В. И.; Sivaraman, K. R.

doi:10.1007/bf00149112

Cited by 116 publications

(51 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Table 1 also shows that the times of reversal completion are close to the cessation times of HL PEs and several months after the end of B ∼ 0 conditions. RTTP and the polarity reversal can be episodic (Howard & Labonte 1981;Topka et al 1982;Makarov & Sivaraman 1989;Krivova & Solanki 2002;Gopalswamy et al 2003a;Ulrich & Tran 2013;Petrie 2015;Sun et al 2015;Mordvinov et al 2016), directly related to the series of poleward surges of alternating polarity. Surface flux transport simulations show that the emergence of a number of large active regions that violate Joy's law leads to the weak polar field during the Cycle 23/24 minimum (Jiang et al 2015).…”

Section: Sdo Pes and Poleward Flux Surgesmentioning

confidence: 99%

Unusual Polar Conditions in Solar Cycle 24 and Their Implications for Cycle 25

Gopalswamy

Yashiro

Akiyama

2016

ApJL

View full text Add to dashboard Cite

We report on the prolonged solar-maximum conditions until late 2015 at the north-polar region of the Sun indicated by the occurrence of high-latitude prominence eruptions (PEs) and microwave brightness temperature close to the quiet-Sun level. These two aspects of solar activity indicate that the polarity reversal was completed by mid-2014 in the south and late 2015 in the north. The microwave brightness in the south-polar region has increased to a level exceeding the level of the Cycle 23/24 minimum, but just started to increase in the north. The northsouth asymmetry in the polarity reversal has switched from that in Cycle 23. These observations lead us to the hypothesis that the onset of Cycle 25 in the northern hemisphere is likely to be delayed with respect to that in the southern hemisphere. We find that the unusual condition in the north is a direct consequence of the arrival of poleward surges of opposite polarity from the active region belt. We also find that multiple rush-to-the-pole episodes were indicated by the PE locations that lined up at the boundary between opposite-polarity surges. The high-latitude PEs occurred in the boundary between the incumbent polar flux and the insurgent flux of opposite polarity.

show abstract

Section: Sdo Pes and Poleward Flux Surgesmentioning

confidence: 99%

Unusual Polar Conditions in Solar Cycle 24 and Their Implications for Cycle 25

Gopalswamy

Yashiro

Akiyama

2016

ApJL

View full text Add to dashboard Cite

show abstract

“…In the extended butterfly diagram (Makarov & Sivaraman 1989), one can see the poleward migration of the magnetic fields indicated by the migration pattern of a number of tracers such as quiescent prominences or the coronal green line. Stenflo (1988Stenflo ( , 1994 analyzed 33 yr of synoptic observations of the Sun's magnetic field carried out daily at the Mount Wilson and Kitt Peak observatories over all solar latitudes and longitudes.…”

Section: Poloidal Fieldmentioning

confidence: 99%

Dynamics of the fast solar tachocline

Forgács‐Dajka¹

2004

A&A

View full text Add to dashboard Cite

Abstract. We present detailed numerical calculations of the fast solar tachocline based on the assumption that the dynamo field dominates over the dynamics of the tachocline. In the present paper of the series, we focus on three shortfalls of the earlier models. First, instead of the simple oscillating dipole poloidal field we study the more general magnetic field structures reminiscent of the butterfly diagram. The migrating field is prescribed as the observed axisymmetric radial magnetic field (Stenflo 1988(Stenflo , 1994. Our results are in good agreement with our analytical estimate and our previous works in , but the polar "dip" in isorotational surfaces is strongly reduced in this case. On the other hand, a more realistic model should have a magnetic diffusivity decreasing significantly inside the radiative interior, so we also explore the effect of diffusivity and magnetic Prandtl number varying with depth. We found that the downwards decreasing magnetic diffusivity and Prandtl number have no significant effect on the solution, although the temporal variation of the tachocline thickness has decreased.

show abstract

“…polar faculae (PFe), in the solar magnetic cycle has been evident since the early work of Waldmeier (1955Waldmeier ( , 1962, Sheeley (1964Sheeley ( , 1966, and Makarov & Sivaraman (1989). The maximum occurrence of PFe, down to heliographic latitudes of |ψ| = 60…”

Section: Introductionmentioning

confidence: 99%

Faculae at the poles of the Sun revisited: infrared observations

Rodríguez¹,

Kneer²

2010

A&A

View full text Add to dashboard Cite

Aims. This study extends earlier investigations on faculae and their small-scale magnetic fields near the solar poles (polar faculaePFe) to measurements of the magnetically sensitive infrared (IR) Fe i lines at 1.5 μm, which provide more accurate information about the magnetic field than lines in the visible spectral range. Methods. PFe were observed with the Tenerife Infrared Polarimeter (TIP II) mounted at the Vacuum Tower Telescope/Observatorio del Teide/Tenerife. Several areas at various heliocentric angles were scanned. Faculae near the solar equator (equatorial faculae -EFe)were also observed for comparison with PFe. The full Stokes vector of the Fe i line pair at 1.5 μm was measured. The magnetic field properties were determined (1) from the centre of gravity (COG); (2) with the weak field approximation (WFA); (3) assuming the strong field regime (SFR); and (4) with inversions under the hypothesis of Milne-Eddington (ME) atmospheres. Line-of-sight (LOS) velocities were determined from the COG of I profiles and from the zero-crossing of the V profiles.

show abstract

New results concerning the global solar cycle

Cited by 116 publications

References 12 publications

Unusual Polar Conditions in Solar Cycle 24 and Their Implications for Cycle 25

Unusual Polar Conditions in Solar Cycle 24 and Their Implications for Cycle 25

Dynamics of the fast solar tachocline

Faculae at the poles of the Sun revisited: infrared observations

Contact Info

Product

Resources

About