Evaluation of the short-term periodicities in the flare index between the years 1966–2002

Özgüç, A.; Ataç, T.; Rybák, J.

doi:10.1007/s11207-004-7304-9

Cited by 34 publications

(4 citation statements)

References 43 publications

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“…Many researchers have investigated these periodicities using various solar activity indicators and methods. They found various periods between 512 and 25 days: such as 450-512 days, 280-364 days, 210-240 days, 150-170 days, 120-130 days, 110-115 days, 73-78 days, 62-68 days, 51-58 days, 41-47 days, and 25-37 days (Lean and Brueckner, 1989;Bai and Sturrock, 1991;Rozelot, 1993;Krivova and Solanki, 2002;Bai, 2003;Ozguc, Atac, and Rybak, 2004;Kane, 2005;Knaack, Stenflo, and Berdyugina, 2005;Obridko and Shelting, 2007;Lara et al, 2008;Kilcik et al, 2010Kilcik et al, , 2014Chowdhury and Dwivedi, 2011;Scafetta and Willson, 2013;Choudhary et al, 2014;Ravindra and Javaraiah, 2015 and references therein).…”

Section: Introductionmentioning

confidence: 98%

Active Latitude Oscillations Observed on the Sun

et al. 2016

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We investigate periodicities in the mean heliographic latitudes of sunspot groups, called active latitudes, for the past six complete solar cycles (1945 -2008). For this purpose, the multitaper method and Morlet wavelet analysis were used. We found that solar rotation periodicities (26 -38 days) are present in active latitudes of both hemispheres for all the investigated cycles (18 to 23). Both in the northern and southern hemispheres, active latitudes drifted toward the equator from the beginning to the end of each cycle and followed an oscillating path. These motions are well described by a second-order polynomial. There are no meaningful periods of between 55 and about 300 days in either hemisphere for all cycles. A periodicity of 300 to 370 days appears in both hemispheres for Cycle 23, in the northern hemisphere for Cycle 20, and in the southern hemisphere for Cycle 18.

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Section: Introductionmentioning

confidence: 98%

Active Latitude Oscillations Observed on the Sun

et al. 2016

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“…To measure the amount of total energy emitted by the solar flare in the Hα wavelength (6563Å), flare index (FI) which describes the short lived solar activity was introduced in [8]; FI � it, (1) where i represents the importance scale of a flare in Hα and it is based on the size and brightness of the flaring area and t describes the duration (in minutes) of the flare (for detail see, [9]). e temporal variation of FI follows the general solar activity variation.…”

Section: Introductionmentioning

confidence: 99%

“…e periodic variation of solar activity indices is investigated by using different indicators such as sunspot number and area, TSI, 10.7 cm solar radio flux, and flare index [5,[10][11][12]. e well-known periodic variations are the 27-day synodic rotation and 11-year Schwabe Cycle due to solar internal dynamo [9,13]. Apart from these two, the 51-, 75-, 154-, and 323-day and 1.3-, 1.8-, and 3.5-year periodicities are also reported in the literature [5,10,12,[14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Periodic Variation of Solar Flare Index for the Last Solar Cycle (Cycle 24)

Özgüç

Kılçık

Sarp

et al. 2021

Advances in Astronomy

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In this study, we used the flare index (FI) data taken from Kandilli Observatory for the period of 2009–2020. The data sets are analyzed in three categories as Northern Hemisphere, Southern Hemisphere, and total FI data sets. Total FI data set is obtained from the sum of Northern and Southern Hemispheric values. In this study, the periodic variations of abovementioned three categories FI data sets were investigated by using the MTM and Morlet wavelet analysis methods. The wavelet coherence (XWT) and cross wavelet (WTC) analysis methods were also performed between these data sets. As a result of our analysis, the following results were found: (1) long- and short-term periodicities ( 2048 ± 512 day and periodicities smaller than 62 days) exist in all data sets without any exception at least with 95 % confidence level; (2) all periodic variations were detected maximum during the solar cycle, while during the minima, no meaningful period is detected; (3) some periodicities have data preference that about 150 days Rieger period appears only in the whole data set and 682-, 204-, and 76.6-day periods appear only in the Northern Hemisphere data sets; (4) During the Solar Cycle 24, more flare activity is seen at the Southern Hemisphere, so the whole disk data periodicities are dominated by this hemisphere; (5) in general, there is a phase mixing between Northern and Southern Hemisphere FI data, except about 1024-day periodicity, and the best phase coherency is obtained between the Southern Hemisphere and total flare index data sets; (6) in case of the Northern and Southern Hemisphere FI data sets, there is no significant correlation between two continuous wavelet transforms, but the strongest correlation is obtained for the total FI and Southern Hemisphere data sets.

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“…Many authors reported fluctuations to depend on the phase of the solar cycle and the time resolution (Chowdhury et al 2015, Singh et al 2019b. Scientists reported different indicators to observe solar activity like sunspot number (Krivova and Solanki 2002, Li et al 2005, Joshi et al 2006, Kiliç 2008, Chowdhury et al 2019, Singh et al 2019b, coronal index (Singh et al 2018), the solar flare index (Özgüç et al 2003(Özgüç et al , 2004(Özgüç et al , Li et al 2010. Studies have also been devoted to discussing the variability of cosmic ray data at different time scales (Chowdhury et al 2010, Chowdhury et al 2015, Singh and Badruddin, 2015a, Singh and Badruddin 2015b, Chowdhury and Kudela 2018, Singh et al 2019b, López-Comazzi and Blanco 2020.…”

Section: Introductionmentioning

confidence: 99%

Solar rotational period of cosmic rays and solar activity during the maximum phase of solar cycle 24

Singh¹,

Farid²,

Singh³

et al. 2021

Phys. Scr.

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To study the solar rotational oscillation on daily averaged time series of solar activity proxies: sunspot number (SSN), modified coronal index (MCI), solar flare index (FI), and cosmic ray intensity (CRI) are subjected to Lomb/Scargle periodogram, and continuous wavelet transform. For this purpose, we have used data of all the considered parameters from 2012 to 2015, which covers the maximum phase including the polarity reversal period of the solar cycle 24. Both spectral analysis techniques are carried out to study the behavior of 27-days on the time scale of the synodic period and to follow their evolution throughout the epoch. Further, we have used R package RobPer (least square regression) techniques and obtained a significant true period ∼27 days is present in this study. It is noted that the ∼27-day period of solar activity parameters and cosmic rays is much prominent during the examined period.

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Evaluation of the short-term periodicities in the flare index between the years 1966–2002

Cited by 34 publications

References 43 publications

Active Latitude Oscillations Observed on the Sun

Active Latitude Oscillations Observed on the Sun

Periodic Variation of Solar Flare Index for the Last Solar Cycle (Cycle 24)

Solar rotational period of cosmic rays and solar activity during the maximum phase of solar cycle 24

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