The 156-day quasi-periodicity in solar indices

Akimov, L. A.; Belkina, I. L.

doi:10.3103/s0884591311030032

Cited by 2 publications

(6 citation statements)

References 10 publications

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“…The conclu sion obtained earlier (Akimov and Belkina, 2011) is confirmed to the effect that the stable dependence of the RQ amplitude of the index W upon the cycle phase and cycle height at the maximum is not observed.…”

Section: Conclusion and Discussionsupporting

confidence: 88%

“…We have shown in (Akimov and Belkina, 2011) that the methods of Fourier analysis with sliding window and wavelet analysis give consistent results. It has been noted that the wavelet analysis made it possible to reveal more delicate features of the time variations in quasi periodicity.…”

Section: Data Series and Methodssupporting

confidence: 64%

“…The continuous wavelet transform of data was also performed in (Akimov and Belkina, 2011) for the series of the N Х index using the Morlet wavelet = as a basis. The temporal behavior of the modulus of spectral density of the wavelet transform of the N Х series demonstrated that the RQ had an inter mittent character, and was most significant in solar cycle 21.…”

Section: Data Series and Methodsmentioning

confidence: 99%

“…2b shows a level of significance of the RQ amplitude (see Akimov and Belkina, 2011). The curve of time dependence of the index W itself is given in Fig.…”

Section: Temporal Peculiarities Of Rq Behavior For Different Indicesmentioning

confidence: 99%

“…This will provide an opportunity to identify regularities of the RQ occurrence more reliably. We studied the RQ (Akimov and Belkina, 2011) by fluctuations of the index W over a period from 1900 to 2008. In this work, the W series is extended on both sides, the beginning of the series is Jan 1, 1849, and its duration is 161 years.…”

Section: Introductionmentioning

confidence: 99%

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Rieger quasi-periodicity in solar indices

Akimov

Belkina

2012

Sol Syst Res

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Using wavelet analysis and Fourier analysis, the temporal behavior of ≈156 day quasi periodicity (Rieger quasi periodicity, RQ) is investigated for series of daily solar indices: Wolf numbers W for 161 years (from 1849), the flux F 10.7 of the Sun's radio emission at a frequency of 2800 MHz for 63 years (from 1947), the number of X ray flares N X for 29 years (from 1981), and the number of optical flares N α for 11 years in cycle 21. The N α series are studied for four quadrants of the solar disk. It is found for the W series that there is no stable dependence of the amplitude RQ on the cycle phase and the W value. It is associated with the fact that, cor responding to a period of around eight years, in the power spectrum changes in the amplitude of the Rieger quasi periodicity of the index W are dominated by the peak. Moreover, the peaks corresponding to the 11 year cyclicity are also significant. The comparative study of the temporal behavior of the Rieger quasi periodicity ampli tude of the indices W, F 10.7 , and N X has shown that the quasi periodicity covers the processes, occurring in active regions on the Sun at different altitudes, almost simultaneously. It is found that for N α , the lag of vari ations of the Rieger quasi periodicity amplitude for series of the Sun's western hemisphere, relative to those for series of the eastern hemisphere, is on average less than for the flare series. Thus, if the flare occurrence is modulated by the Rieger quasi periodicity process as a wave propagating over the Sun's disc, then the wave is not a retrograde one. Different interpretations of the nature of the Rieger quasi periodicity are discussed including the hypothesis of Rossby waves.

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Section: Conclusion and Discussionsupporting

confidence: 88%

Section: Data Series and Methodssupporting

confidence: 64%

Section: Data Series and Methodsmentioning

confidence: 99%

“…2b shows a level of significance of the RQ amplitude (see Akimov and Belkina, 2011). The curve of time dependence of the index W itself is given in Fig.…”

Section: Temporal Peculiarities Of Rq Behavior For Different Indicesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rieger quasi-periodicity in solar indices

Akimov

Belkina

2012

Sol Syst Res

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Measuring the Solar Radius From Space During the 2003 and 2006 Mercury Transits

Emílio

Kuhn

Bush

et al. 2012

ApJ

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The Michelson Doppler Imager (MDI) aboard the Solar and Heliospheric Observatory observed the transits of Mercury on 2003 May 7 and 2006 November 8. Contact times between Mercury and the solar limb have been used since the 17th century to derive the Sun's size but this is the first time that high-quality imagery from space, above the Earth's atmosphere, has been available. Unlike other measurements this technique is largely independent of optical distortion. The true solar radius is still a matter of debate in the literature as measured differences of several tenths of an arcsecond (i.e., about 500 km) are apparent. This is due mainly to systematic errors from different instruments and observers since the claimed uncertainties for a single instrument are typically an order of magnitude smaller. From the MDI transit data we find the solar radius to be 960".12 ± 0".09 (696, 342 ± 65km). This value is consistent between the transits and consistent between different MDI focus settings after accounting for systematic effects.

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The 156-day quasi-periodicity in solar indices

Cited by 2 publications

References 10 publications

Rieger quasi-periodicity in solar indices

Rieger quasi-periodicity in solar indices

Measuring the Solar Radius From Space During the 2003 and 2006 Mercury Transits

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