Solar-cycle-related variation of solar differential rotation

Li, K. J.; Shi, X. J.; Xie, J. L.; Gao, P. X.; Liang, Hong; Zhan, L. S.; Wen, Feng

doi:10.1093/mnras/stt744

Cited by 23 publications

(12 citation statements)

References 48 publications

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“…Certain differences in the characteristics of differential rotation in the northern and southern hemispheres have been reported by many authors (e.g., see Badalyan & Sýkora 2006;Zhang et al 2011;Rightmire-Upton et al 2012;Li et al 2013). Anyway, the theory does not forbid the violation of differential rotation.…”

Section: Main Conclusion and Discussionmentioning

confidence: 90%

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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Section: Main Conclusion and Discussionmentioning

confidence: 90%

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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“…However, the higher values of sunspot can be found on the solar surface; thus, the more magnetic flux erupts from solar interior towards the solar surface, which provides favourable conditions for the appearance of Rieger-type periodicity. Moreover, the variation of differential rotation parameters on the solar surface does not show high amplitude near the maximum times of solar activity cycle (Brajša et al 2006;Li et al 2013aLi et al , 2013b. According to relation of the parameters on the solar surface and that in the tachocline (Howe et al 2000b;Howe 2009), the variation of differential rotation parameters in the tachocline is also small.…”

Section: Discussionmentioning

confidence: 94%

“…The authors considered that the variation of the differential rotation parameters through the solar cycle in the tachocline only permits the strong growth of the magnetic Rossby waves only during the solar maximum, and which can interpret the appearance of Rieger-type periodicity only during the solar maximum. It is difficult to study the temporal evolution of differential rotation parameters in the tachocline, but the studies on solar-cycle-related variation of differential rotation parameters based on investigation sunspots on the solar surface show that strong magnetic fields repress differential rotation, while weak magnetic fields more reflect differentiation of rotation rates; the differential rotation parameters are smaller near the maximum times of solar activity cycle (about the fourth to the seventh year after the minimum of a solar cycle) than that in the other solar activity phases (Brajša, Ruždjak, & Wöhl 2006;Li, Xie, & Shi, 2013b). Though the variation of differential rotation parameters in the tachocline which is due to torsional oscillations (LaBonte & Howard 1982;Howe et al 2000aHowe et al , 2005Howe 2009) is different from that on the solar surface, the relation of the parameters on the solar surface and that in the tachocline (Howe et al 2000b;Howe 2009) indicates that the results obtained from the early studies of sunspots on the solar surface may reflect the variation of differential rotation parameters in the tachocline to some extent.…”

Section: Discussionmentioning

confidence: 99%

“…Because the eruption of magnetic flux from solar interior towards the solar surface is connected to tachocline, the weak hemispheric activity in northern and southern hemispheres indicates that the weak magnetic activity in the tachocline during these solar cycles. The strong magnetic fields repress differential rotation, while weak magnetic fields more reflect differentiation of rotation rates (Zaatri et al 2009;Wöhl et al 2010 ;Jurdana-šepić et al 2011;Li et al 2013aLi et al , 2013b. Thus, the relatively weak magnetic activity in the tachocline may indicate the higher values of differential rotation parameters in this layer, but the variation of the parameters through the solar cycle may be more complex.…”

Section: Discussionmentioning

confidence: 99%

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The cause of the appearance or disappearance of the Rieger-type periodicity in the northern and southern hemispheres of the sun

Xiang

Zhao

2021

Publ. Astron. Soc. Aust.

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We use a continuous wavelet transform to analyse the daily hemispheric sunspot area data from the Greenwich Royal Observatory during cycles 12–24 and then study the cause of the appearance or disappearance of the Rieger-type periodicity in the northern and southern hemispheres during a certain cycle. The Rieger-type periodicity in the northern and southern hemispheres should be developed independently in the two hemispheres. This periodicity in the northern hemisphere is generally anti-correlated with the long-term variations in the mean solar cycle strength of hemispheric activity, but the correlation of the two parameters in the southern hemisphere shows a weak correlation. The appearance or disappearance of Rieger-type periodicity in the northern and southern hemispheres during a certain solar cycle is not directly correlated with their corresponding hemispheric mean activity strength but should be related to the strength of the hemispheric activity during sunspot maximum times, which hints the Rieger-type periodicity is more related to temporal evolution of toroidal magnetic field. The Rieger-type periodicity in the two hemispheres disappears in those solar cycles with relatively weak hemispheric activity during sunspot maximum times. The reason for the disappearance of this periodicity may be due to the combined influence of relatively weak toroidal magnetic fields and torsional oscillations, the differential rotation parameters vary through the solar cycle and may not remain more or less unchanged during some time, which does not permit the strong growth of magnetic Rossby waves.

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“…e sunspot number in the same period is decomposed into 5 IMF components, and there exists quasiperiodicity of about 102.2a, 52.2a, and 11a. e 11a cycle obtained by multiscale analysis of sunspot number by VMD and Hilbert transform is the famous Schwabe [31] cycle, and the variance contribution rate is as high as 57.91%. It is the most significant.…”

Section: Discussionmentioning

confidence: 99%

Cycle Analysis Method of Tree Ring and Solar Activity Based on Variational Mode Decomposition and Hilbert Transform

Zheng

Yang

2019

Advances in Meteorology

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According to the correlation of tree ring and solar activity, the cycle analysis method based on variational mode decomposition (VMD) and Hilbert transform is proposed. Firstly, the tree ring width of cypress during 1700 to 1955 beside the Huangdi Tomb and the long-term sunspot number during 1700 to 1955, respectively, are decomposed by VMD into a series of intrinsic mode functions (IMFs). Secondly, Hilbert transformation on the decomposed IMF component is performed. Then, the marginal spectra are given and analyzed. Finally, their quasiperiodic properties are obtained as follows: the tree ring width has the quasiperiodicity of 2 to 7a, 10.8a, and 25a; the sunspot number has the quasiperiodicity of 8.3a, 9.9a, 11.1a, 52.2a, and 101.2a. The result obtained by analyzing that quasiperiodicity shows that the main periods of tree ring width and the sunspot number in the same period are basically consistent, and tree ring width has other cycles. This shows that sunspot activity is an important factor affecting tree ring growth, and tree ring width is influenced by other external environments.

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Solar-cycle-related variation of solar differential rotation

Cited by 23 publications

References 48 publications

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

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

The cause of the appearance or disappearance of the Rieger-type periodicity in the northern and southern hemispheres of the sun

Cycle Analysis Method of Tree Ring and Solar Activity Based on Variational Mode Decomposition and Hilbert Transform

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