Periodicities of solar irradiance and solar activity indices, I

Pap, J. M.; Tobiska, W. Kent; Bouwer, S. Dave

doi:10.1007/bf00154372

Cited by 177 publications

(91 citation statements)

References 35 publications

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“…However, the 27 day periodicity refers to the solar rotation, which is most common due to all the active centers or exciter hotspot being very close to the equator, particularly during the declining phase of the solar cycle. Our results endorse the earlier conclusion by Pap et al (1990) that this periodicity arises because active regions and their magnetic field are better organized and are long-lived during the maximum and declining portions of the solar cycle compared with the rising portion. Our discovery of a 31 day periodicity, though not prominent, in all the energy bands suggests that many sunspot regions did not approach close to the equator during the declining phase of cycle 23.…”

Section: Discussionsupporting

confidence: 92%

Periodicities in the X-Ray Emission From the Solar Corona

Chowdhury

Jain

Awasthi

2013

ApJ

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We have studied the time series of full disk integrated soft and hard X-ray emission from the solar corona during 2004 January to 2008 December, covering the entire descending phase of solar cycle 23 from a global point of view. We employ the daily X-ray index derived from 1 s cadence X-ray observations from the Si and CZT detectors of the "Solar X-ray Spectrometer" mission in seven different energy bands ranging between 6 and 56 keV. X-ray data in the energy bands 6-7, 7-10, 10-20, and 4-25 keV from the Si detector are considered, while 10-20, 20-30, and 30-56 keV high energy observations are taken from the CZT detector. The daily time series is subjected to power spectrum analysis after appropriate correction for noise. The Lomb-Scargle periodogram technique has shown prominent periods of ∼13.5 days, ∼27 days, and a near-Rieger period of ∼181 days and ∼1.24 yr in all energy bands. In addition to this, other periods like ∼31, ∼48, ∼57, ∼76, ∼96, ∼130, ∼227, and ∼303 days are also detected in different energy bands. We discuss our results in light of previous observations and existing numerical models.

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Section: Discussionsupporting

confidence: 92%

Periodicities in the X-Ray Emission From the Solar Corona

Chowdhury

Jain

Awasthi

2013

ApJ

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“…Except for 33.5 and 85 day periodicities, all the periodicities have periods very close to integral multiples of 25.5 days. In addition, analyses of daily sunspot areas have detected periodicities at 51 days (Pap et al 1990) and 78 days (Bai & Sturrock 1991). Second, except for the 34 day periodicity, all the periodicities are visually recognizable in time profiles of flare rates smoothed with a 27 day moving window.…”

Section: Summary and Discussionmentioning

confidence: 94%

“…This periodicity was also detected from data of times earlier than cycle 19: cycle 2 (Ballester, Oliver, & Baudin 1999) and cycles 16-18 (Carbonell & Ballester 1992;Oliver et al 1998;Ballester et al 1999;Krivova & Solanki 2002), but not cycles 12-15 (Carbonell & Ballester 1992). In addition to the 154 day periodicity, Pap, Tobsika, & Bouwer (1990) discovered a 51 day periodicity in active sunspot areas (areas of growing sunspot groups) of cycle 21. Results of periodicity analyses of sunspot numbers generally agree with the results of sunspot area analyses (Lean & Brueckner 1989;Krivova & Solanki 2002), but Verma & Joshi (1987), for some reason, did not detect the 154 day periodicity from sunspot numbers of cycle 21.…”

Section: Introductionmentioning

confidence: 99%

Periodicities in Solar Flare Occurrence: Analysis of Cycles 19–23

Bai

2003

ApJ

128

100

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Midrange periodicities in solar flare occurrence have been analyzed with new methods for cycles 19-23. During cycle 23, periodicities of 129 and 33.5 days were in operation. Five episodes of high activity occurred periodically with the 129 day period. The 33.5 day periodicity mainly operated for energetic flares. Results for cycles 19-21 are generally in agreement with previous analyses. For cycle 19, the 51 day periodicity is confirmed to be statistically significant. In the spectrum for cycle 20, two peaks are found at 84 and 129 days. The 129 day periodicity was in operation for eight cycles of 129 days. The 153 day periodicity, which operated during cycle 21, was more effective for modulating occurrence rates of energetic flares than for those of less energetic flares. No statistically significant periodicities are found from occurrence rates of energetic flares (!M1.0) of cycle 22. In the power spectra of major flare occurrence times for the time intervals analyzed by Ozguc and Atac and by Bai, the strongest peaks are found at 73, 76, and 51 days, in agreement with their results, but these periodicities are not statistically significant. It is interesting that the periods of 51, 129, and 153 days are very close to integral multiples of 25.5 days.

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“…Lean and Brueckner (1989) found it in the power spectrum of the sunspot-blocking function, in the 10.7-cm radio flux, the sunspot number, and in the plage-index daily data during three solar cycles (19 -21). Pap, Tobiska, and Bouwer (1990) showed that an 8 -11 month period existed in the total and UV irradiances (1980 and 1982 -1988, respectively), in the 10.7-cm radio flux (1947 -1989), the Ca K plage index (1970 -1987), the sunspot blocking function (1874 -1982), and the Mg II core-wing ratio (1978 -1986). Akioka et al (1987) detected it in areas and numbers of sunspot groups from 1969 to 1986.…”

Section: Introductionmentioning

confidence: 99%

The Ten-Rotation Quasi-periodicity in Sunspot Areas

Getko

2013

Sol Phys

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Sunspot-area fluctuations over an epoch of 12 solar cycles (12 -23) are investigated in detail using wavelets. Getko (Universal Heliophysical Processes, IAU Symp. 257, 169, 2009) found three significant quasi-periodicities at 10, 17, and 23 solar rotations, but two longer periods could be treated as subharmonics of the ten-rotation quasi-periodicity. Therefore we focused the analysis on the occurrence of this quasi-periodicity during the low-and high-activity periods of each solar cycle. Because of the N -S asymmetry, each solar hemisphere was considered separately. The skewness of each fluctuation-probability distribution suggests that the positive and negative fluctuations could be examined separately. To avoid the problem that occurs when a few strong fluctuations create a wavelet peak, we applied fluctuation transformations for which the amplitudes at the high-and the low-activity periods are almost the same. The wavelet analyses show that the ten-rotation quasi-periodicity is mainly detected during the high-activity periods, but it also exists during a few low-activity periods. The division of each solar hemisphere into 30• -wide longitude bins and the wavelet calculations for the areas of sunspot clusters belonging to these 30• bins enable one to detect longitude zones in which the ten-rotation quasi-periodicity exists. These zones are present during the whole high-activity periods and dominate the integrated spectra.

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Periodicities of solar irradiance and solar activity indices, I

Cited by 177 publications

References 35 publications

Periodicities in the X-Ray Emission From the Solar Corona

Periodicities in the X-Ray Emission From the Solar Corona

Periodicities in Solar Flare Occurrence: Analysis of Cycles 19–23

The Ten-Rotation Quasi-periodicity in Sunspot Areas

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