22-year cycle of differential rotation of the solar corona and the rule by Gnevyshev–Ohl

Badalyan, O. G.; Обридко, В. Н.

doi:10.1093/mnras/stx134

Cited by 13 publications

(18 citation statements)

References 14 publications

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“…This is most probably due to the errors, which are more pronounced at the beginning of the dataset where the amount of available data in years near minima is low. Badalyan and Obridko (2017) examined the 22-year cycle of differential rotation and the rule of Genevyshev-Ohl by using the green coronal line brightness data from 1943 onward and obtained a result consistent with inverse correlation of both differential-rotation parameters and activity (see Figures 3 and 4 in Badalyan and Obridko, 2017). Their finding of larger increases of equatorial rotation velocity between even and odd cycle than between odd and even is not visible in our data (see Figure 1).…”

Section: Discussionsupporting

confidence: 67%

“…This is not so clear for the differential-rotation parameter B where no secular changes were found. The larger average rotation velocities in minimum than in other phases of cycle, i.e., inverse correlation between solar equatorial-rotation rate and activity, was found by many authors using different methods and data (Lustig, 1983;Gilman and Howard, 1984;Balthasar, Vazquez, and Wöhl, 1986;Gupta, Sivaraman, and Howard, 1999;Zuccarello and Zappalá, 2003;Brajša, Ruždjak, and Wöhl, 2006;Jurdana-Šepić et al, 2011;Li et al, 2014;Badalyan and Obridko, 2017). Brun (2004) numerically modelled the interaction of convection and rotation with magnetic field in deep spherical shells and found that the increase of magnetic field would result in the reduction of differential rotation.…”

Section: Discussionmentioning

confidence: 95%

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A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

et al. 2017

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The sunspot position from Greenwich Photoheliographic Results (GPR), US Air Force Solar Optical Observing Network and National Oceanic and Atmospheric Administration (USAF/NOAA), and Debrecen Photoheliographic Data (DPD) data bases in the period 1874 to 2016 were used to calculate yearly values of the solar differential-rotation parameters A and B. The calculated differential-rotation parameters were compared with the solar-activity level. We found that the Sun rotates more differentially at the minimum than at the maximum of activity during the 1977 -2016 epoch. An inverse correlation between equatorial rotation and solar activity was found using the recently revised sunspot number. The secular decrease of equatorial rotation rate accompanying the increase of activity stopped in the last part of the 20th century. It was noted that when a significant peak of equatorial rotation velocity is observed during minimum of activity, the strength of the next maximum is smaller than the previous one.

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Section: Discussionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 95%

A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

et al. 2017

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“…That is to say, the total rotation of the solar corona could be described as a superposition of two rotation modes: the fast mode near the equator is around 27 days, and the slow mode exceeds 30 days (Badalyan 2010). Using the same but longer database, Badalyan & Obridko (2017) investigated the time variation of the differential rotation parameters of the solar corona, and found that the equatorial rotation rate of the corona increases in the epochs of minimum between the even and odd cycles and arrives at its minimum values between the odd and even cycles. They suggested that the 22-year cycle of differential rotation pattern could be used to explain the effect by the Gnevyshev-Ohl rule.…”

Section: Introductionmentioning

confidence: 99%

Systematic regularity of solar coronal rotation during the time interval 1939–2019

Deng

Zhang

Deng

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Temporal variation of the solar coronal rotation appears to be very complex and its relevances to the eleven-year solar activity cycle are still unclear. Using the modified coronal index for the time interval from 1939 January 1 to 2019 May 31, the systematic regularities of the solar coronal rotation are investigated. Our main findings are as follows: (1) from a global point of view, the synodic coronal rotation period with a value of 27.5 days is the only significant period at the periodic scales shorter than 64 days; (2) the coronal rotation period exhibit an obviously decreasing trend during the considered time interval, implying the solar corona accelerates its global rotation rate in the long run; (3) there exist significant periods of 3.25, 6.13, 9.53, and 11.13 years in the period length of the coronal rotation, providing an evidence that the coronal rotation should be connected with the quasi-biennial oscillation, the eleven-year solar cycle, and the 22-year Hale cycle (or the magnetic activity reversal); and (4) the phase relationship between the coronal rotation period and the solar magnetic activity is not only time-dependent but also frequency-dependent. For a small range around the 11-year cycle band, there is a systematic trend in the phase, and the small mismatch in this band brings out the phase to drift. The possible mechanism for the above analysis results is discussed.

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“…The correlation coefficient for the curves on the right panel in the range of the periods from 50 to 250 months is 0.94. On both periodograms, the 11-yr period is weakly pronounced; however, one can clearly identify a quasi-period of 12 yr. Figure 4 represents spectral variation diagrams (SVD) for the asymmetry A (top) and the asymmetry sign sgn A (bottom) (SVD construction method is described in Badalyan et al 2005;Badalyan & Obridko 2009, 2011. A 132-month moving window was applied for calculations with a shift of 12 months.…”

Section: Basic Properties Of North-south Asymmetry Signmentioning

confidence: 99%

“…From the above it is clear that it makes sense to examine separately the asymmetry sign and its absolute value (Obridko & Badalyan 2009). The problem under discussion is formulated in Sect.…”

Section: Introductionmentioning

confidence: 99%

North-south asymmetry of solar activity as a superposition of two realizations – the sign and absolute value

Badalyan

Обридко

2017

A&A

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Context. Since the occurrence of north-south asymmetry (NSA) of alternating sign may be determined by different mechanisms, the frequency and amplitude characteristics of this phenomenon should be considered separately. Aims. We propose a new approach to the description of the NSA of solar activity. Methods. The asymmetry defined as A = (N − S)/(N + S) (where N and S are, respectively, the indices of activity of the northern and southern hemispheres) is treated as a superposition of two functions: the sign of asymmetry (signature) and its absolute value (modulus). This approach is applied to the analysis of the NSA of sunspot group areas for the period 1874-2013. Results. We show that the sign of asymmetry provides information on the behavior of the asymmetry. In particular, it displays quasi-periodic variation with a period of 12 yr and quasi-biennial oscillations as the asymmetry itself. The statistics of the so-called monochrome intervals (long periods of positive or negative asymmetry) are considered and it is shown that the distribution of these intervals is described by the random distribution law. This means that the dynamo mechanisms governing the cyclic variation of solar activity must involve random processes. At the same time, the asymmetry modulus has completely different statistical properties and is probably associated with processes that determine the amplitude of the cycle. One can reliably isolate an 11-yr cycle in the behavior of the asymmetry absolute value shifted by half a period with respect to the Wolf numbers. It is shown that the asymmetry modulus has a significant prognostic value: the higher the maximum of the asymmetry modulus, the lower the following Wolf number maximum. Conclusions. A fundamental nature of this concept of NSA is discussed in the context of the general methodology of cognizing the world. It is supposed that the proposed description of the NSA will help clarify the nature of this phenomenon.

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22-year cycle of differential rotation of the solar corona and the rule by Gnevyshev–Ohl

Cited by 13 publications

References 14 publications

A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

Systematic regularity of solar coronal rotation during the time interval 1939–2019

North-south asymmetry of solar activity as a superposition of two realizations – the sign and absolute value

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