The rotation signal in daily sunspot areas

Li, K. J.; Hu, Liang; Wen, Feng; Zhan, L. S.

doi:10.1007/s10509-010-0451-6

Cited by 23 publications

(16 citation statements)

References 36 publications

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“…A weak decreasing trend is found in the coronal rotation cycle length, but this is statistically insignificant. However, for sunspots, a secular decreasing trend has been found in the Sun’s rotation cycle length, which is statistically significant (Li et al 2011a,b).…”

Section: Discussionmentioning

confidence: 98%

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Long-term variations of the coronal rotation and solar activity

Shi

Wen

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Recently, Chandra and Vats have obtained the yearly period length of the solar coronal rotation cycle by analysing the daily adjusted solar radio flux at the 10.7‐cm wavelength for the years 1947–2009. In this paper, we use the time series (series I) of the yearly period length to investigate the long‐term variation of the rotation of radio emission corona, and we find a weak decreasing trend in the time series. We use the empirical mode decomposition to decompose both the yearly mean value (series II) of the solar radio flux at the 10.7‐cm wavelength and series I into different periodical components. There is a secular trend for each of the two series, and we find a negative correlation in the two trends. The decomposed 11‐yr‐cycle components of the two series show different and complicated periods and there is a phase relation between them. We investigate the cycle‐related variation of the coronal rotation length, and we find that there is no Schwable cycle of statistical significance for the long‐term variation of the rotation cycle length.

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Section: Discussionmentioning

confidence: 98%

“…Thus, no secular trend is found to be statistically prominent. Li et al (2011a,b) have also found a secular decreasing trend in the length of the Sun’s rotation cycle by analysing sunspot activity. Furthermore, such a trend is statistically significant.…”

Section: Long‐term Variations Of the Coronal Rotation And Solar Actmentioning

confidence: 97%

Long-term variations of the coronal rotation and solar activity

Shi

Wen

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…Previous studies (see Heristchi & Mouradian 2009;Li et al 2011a;Xie et al 2012Xie et al , 2017b on the secular trend of the solar rotation period have often revealed a general decreasing trend in the solar rotation period. It should be pointed out that these studies focused on the sunspot activity and the corona radio flux.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…That is to say, in the local wavelet power spectra shown in Figure 7, the rotation period length at a certain time point has the highest power spectrum among the periodic scales of 24-30 days, where are the length range of coronal rotation period located . Based on this conception, the rotation period length of sunspot numbers (Li et al 2011a;Xie et al 2012), sunspot areas (Li et al 2011b), solar mean magnetic field (Xie et al 2017a), and 10.7 cm solar radio flux (Xie et al 2017b) are studied and estimated. In this sense, the similar procedure could be also applied to obtain the period length of the coronal rotation (PLCR) of daily MCI at each time point during the considered time interval, and the extracted results are shown in Figure 9.…”

Section: Temporal Variation Of Coronal Rotationmentioning

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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“…Up to now, observations and studies on solar differential rotation have taken a great achievement (Howard 1984;Schroter 1985;Snodgrass 1992; Paterno 2010; Vats & Chandra 2011;Vats 2012). However, there are still many aspects, for example, the solar-cycle related and long-term variations of solar rotation rate, unknown at the present (Komm, Howard & Harvey 1993;Ulrich & Bertello 1996;Stix 2002;Li et al 2011aLi et al , 2011b. In this study, we will investigate solar-cycle related variation of solar rotation rate, using data of the rotation rates of magnetic fields, distributed along latitudes and varying with time at the time interval of August 1976 to April 2008, and a new explanation is proposed on such a solar-cycle related variation of the solar rotation rate.…”

Section: Introductionmentioning

confidence: 99%

Solar-cycle-related variation of solar differential rotation

Li¹,

Shi²,

Xie³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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Solar-cycle related variation of differential rotation is investigated through analyzing the rotation rates of magnetic fields, distributed along latitudes and varying with time at the time interval of August 1976 to April 2008. More pronounced differentiation of rotation rates is found to appear at the ascending part of a Schwabe cycle than at the descending part on an average. The coefficient B in the standard form of differential rotation, which represents the latitudinal gradient of rotation, may be divided into three parts within a Schwabe cycle. Part one spans from the start to the 4 th year of a Schwabe cycle, within which the absolute B is approximately a constant or slightly fluctuates. Part two spans from the 4 th to the 7 th year, within which the absolute B decreases. Part three spans from the 7 th year to the end, within which the absolute B increases. Strong magnetic fields repress differentiation of rotation rates, so that rotation rates show less pronounced differentiation, but weak magnetic fields seem to just reflect differentiation of rotation rates. The solar-cycle related variation of solar differential rotation is inferred to the result of both the latitudinal migration of the surface torsional pattern and the repression of strong magnetic activity to differentiation of rotation rates. Sun: rotation-Sun:activity-Sun: surface magnetism 1 *

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The rotation signal in daily sunspot areas

Cited by 23 publications

References 36 publications

Long-term variations of the coronal rotation and solar activity

Long-term variations of the coronal rotation and solar activity

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

Solar-cycle-related variation of solar differential rotation

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