Chaos and Periodicities in Solar Flare Index from Kandilli Observatory during 1976–2014

Abstract

The Solar Flare Index is regarded as one of the most important solar indices in the field of solarterrestrial research. It has the maximum effect on Earth of all other solar activity indices and is being considered for describing the short-lived dynamo action inside the Sun. This paper attempts to study the short as well as long-term temporal fluctuations in the chromosphere region of the Sun using the Solar Flare Index. The daily Solar Flare Index for Northern, Southern Hemisphere and Total Disk are considered for a period from January 1976 to December 2014 (total 14 245 days) for chaotic as well as periodic analysis. The 0–1 test has been employed to investigate the chaotic behavior associated with the Solar Flare Index. This test revealed that the time series data is non-linear and multi-periodic in nature with deterministic chaotic features. For periodic analysis, the Raleigh Power Spectrum algorithm has been used for identifying the predominant periods within the data along with their confidence score. The well-known fundamental period of 27 days and 11 years along with their harmonics are well affirmed in our investigation with a period of 28 days and 10.77 years. The presence of 14 days and 7 days periods in this investigation states the short-lived action inside the Sun. Our investigation also demonstrates the presence of other mid-range periods including the famous Rieger type period which are very much confirming the results obtained by other authors using various solar activity indicators.

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

“…About 150 days periodicity detected in our study from the whole disc FI data is the Rieger periodicity which was first detected by [14] from the X-ray flare data. It was also detected by [5] as 152 days from the FI data and they argue that this periodicity appears due to the magnetic Rossby waves. Recently, Kilcik et al [30] found the same periodicity from the MCMESI and different class X-ray solar flare data.…”

“…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].…”

“…We found the following results: Later, Tsichla et al [38] investigated the periodicity in some solar and geomagnetic activity indices by using the Lomb-Scargle algorithm and wavelet analysis methods for the time interval of 1965-2018. ey detected 26.7 and 150 days and 1.1, 1.9, and 5.6 years periodicities from monthly data sets of SSN, interplanetary magnetic field, and geomagnetic Ap index. Recently, Roy et al [5] analyzed the periodicities of monthly FI data taken from Kandilli Observatory for the time interval of 1976-2014. ey used Rayleigh power spectrum analysis method and found 5.6, 1.9, and 1.1 years and 28, 152, 260, and 188 days periodicities. ey concluded that the periods of about 85 and 311 days are integral multiplies of 28 days solar rotation period and about 653 days and 1077 days periods are subharmonic of 11-year Schwabe Cycle.…”

“…e amount of released total energy during a large flare is about 10 32 erg. During the flaring activity, solar energetic particles such as electrons, protons, and heavy nuclei are also released and accelerated [4,5]. Especially large flares may produce intense effects on Earth and near space environment [3,6,7].…”

“…Similar to other solar activity indicators, FI also shows periodic behavior from days to tens of years and it is a suitable index to study short and long range periodic behavior of solar activity. 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].…”