Long-Term Variations in Solar Differential Rotation and Sunspot Activity

Javaraiah, J.; Bertello, L.; Ulrich, R. K.

doi:10.1007/s11207-005-8776-y

Cited by 66 publications

(40 citation statements)

References 37 publications

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“…The B parameter was also found to have a small decreasing trend from about B = 2.7 to about B = 2.4, but the evolution of B was dominated by a roughly 80-year oscillation with an amplitude of ±0.3 deg/day. However, these results cannot be directly compared with the long-term evolution of the best-fit values of the two rotation parameters found in this study since Javaraiah et al (2005) did not separately consider the two hemispheres.…”

Section: Discussionmentioning

confidence: 78%

“…Earlier studies have already noted that the rotation parameters depict long-term trends and long-term oscillations (see, e.g., Makarov et al 1997;Kitchatinov et al 1999;Javaraiah et al 2005;Brajsa et al 2006, and references therein). For instance, Javaraiah et al (2005) found that the Ω 0 parameter depicts a fairly systematic decline during cycles 12 to 23 from roughly Ω 0 = 14.55 deg/day to Ω 0 = 14.45 deg/day, with some evidence of weak century-scale oscillation superimposed.…”

Section: Discussionmentioning

confidence: 96%

“…For instance, Javaraiah et al (2005) found that the Ω 0 parameter depicts a fairly systematic decline during cycles 12 to 23 from roughly Ω 0 = 14.55 deg/day to Ω 0 = 14.45 deg/day, with some evidence of weak century-scale oscillation superimposed. The B parameter was also found to have a small decreasing trend from about B = 2.7 to about B = 2.4, but the evolution of B was dominated by a roughly 80-year oscillation with an amplitude of ±0.3 deg/day.…”

Section: Discussionmentioning

confidence: 99%

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Global analysis of active longitudes of sunspots

Zhang

Мурсула

Usoskin

et al. 2011

A&A

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Context. Active longitudes have been found in various manifestations of solar activity. The longitudinal distribution of, e.g., sunspots and solar X-ray flares shows two persistent preferred longitudes separated by roughly 180 degrees. We previously studied solar X-ray flares using an improved version of a dynamic, differentially rotating coordinate system and found enhanced rotational asymmetry and rotation parameter values that are consistent for the three classes of X-ray flares. Aims. We aim to find the optimal values of rotation parameters of active longitudes of sunspots for several different time intervals and separately for the two solar hemispheres. Methods. We perform a global study of the longitudinal location of sunspots (all sunspots and first appearance sunspots) using a refined version of a dynamic, differentially rotating coordinate system. Results. We find that the rotation parameters for sunspots are in good agreement with those obtained for X-ray flares using the same method. The improved method typically finds somewhat faster equatorial rotation with better accuracy. The improved treatment also leads to a larger non-axisymmetry. Rotation parameters for all sunspots and first appearances closely agree with each other, but nonaxisymmetry is systematically larger for all sunspots than for first appearances, suggesting that strong fields follow more closely the pattern of active longitudes. The refined method emphasizes hemispheric differences in rotation. Over the whole interval, the mean rotation in the southern hemisphere is slower than in the north. We also find significant temporal variability in the two rotation parameters over the 136-year interval. Interestingly, the long-term variations (trends and residual oscillations) in solar rotation are roughly the opposite in the northern and southern hemispheres. Conclusions. Rotation parameters vary differently with time in the northern and southern hemispheres. Both sunspots and flares strongly suggest that the northern hemisphere rotated considerably faster but the southern hemisphere slightly slower than the Carrington rotation rate during the last three solar cycles.

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

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Global analysis of active longitudes of sunspots

Zhang

Мурсула

Usoskin

et al. 2011

A&A

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“…This property of the solar activity, known as the Gleissberg cycle, is now well established (Zolotova and Ponyavin, 2014;Vázquez et al, 2016;Komitov et al, 2016). Some authors have suggested that the activity is currently at the minimum of the recent Gleissberg cycle (Javaraiah, Bertello, and Ulrich, 2005a;Zolotova and Ponyavin, 2014;Gao, 2016). In this article we attempt to predict the relative amplitudes of the solar cycles that correspond to the rising phase of the upcoming Gleissberg cycle.…”

Section: Introductionmentioning

confidence: 99%

Will Solar Cycles 25 and 26 Be Weaker than Cycle 24?

Javaraiah¹

2017

Sol Phys

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The study of variations in solar activity is important for understanding the underlying mechanism of solar activity and for predicting the level of activity in view of the activity impact on space weather and global climate. Here we have used the amplitudes (the peak values of the 13-month smoothed international sunspot number) of Solar Cycles 1 -24 to predict the relative amplitudes of the solar cycles during the rising phase of the upcoming Gleissberg cycle. We fitted a cosine function to the amplitudes and times of the solar cycles after subtracting a linear fit of the amplitudes. The best cosine fit shows overall properties (periods, maxima, minima, etc.) of Gleissberg cycles, but with large uncertainties. We obtain a pattern of the rising phase of the upcoming Gleissberg cycle, but there is considerable ambiguity. Using the epochs of violations of the Gnevyshev-Ohl rule (G-O rule) and the 'tentative inverse G-O rule' of solar cycles during the period 1610 -2015, and also using the epochs where the orbital angular momentum of the Sun is steeply decreased during the period 1600 -2099, we infer that Solar Cycle 25 will be weaker than Cycle 24. Cycles 25 and 26 will have almost same strength, and their epochs are at the minimum between the current and upcoming Gleissberg cycles. In addition, Cycle 27 is expected to be stronger than Cycle 26 and weaker than Cycle 28, and Cycle 29 is expected to be stronger than both Cycles 28 and 30. The maximum of Cycle 29 is expected to represent the next Gleissberg maximum. Our analysis also suggests a much lower value (30 -40) for the maximum amplitude of the upcoming Cycle 25.

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“…For the investigation of possible variations in the solar rotation, the Greenwich data set was used by Balthasar & Wöhl (1980), Arévalo et al (1982), and Balthasar et al (1986); the Kanzelhöhe data set by Lustig (1983); the Mt. Wilson data set by Gilman & Howard (1984) and by Hathaway & Wilson (1990); the Mitaka data set by Kambry & Nishikawa (1990); the Suzuka data set by Suzuki (1998); the extended Greenwich data set by Pulkkinen & Tuominen (1998), Javaraiah (2003), Zuccarello & Zappalá (2003), Javaraiah et al (2005), Javaraiah & Ulrich (2006), and Brajša et al (2006Brajša et al ( , 2007; the Kodaikanal data set by Gupta et al (1999); and the Abastumani data set by Khutsishvili et al (2002). Also, temporal variations in the solar rotation were studied using other Article published by EDP Sciences A17, page 1 of 6…”

Section: Introductionmentioning

confidence: 99%