Large Flares (M1–X7) in Solar Activity Cycle 24

Abstract

The large (X-ray class > M1) and very large (X-ray class >X1) flares (according to the observations of GOES-15 and Preliminary data from Current Catalog of Flare Events) in solar activity cycle 24 were analyzed. The monthly average values of optical Flare Index for 2010 -2016 were calculated. The values of the total energy of the flare E (J · m −2 ) in the 0.1 -0.8 nm range at the level of the earth's atmosphere were estimated. The energy spectrum (the dependence of the number of flares with the full energy E from the value of this full energy) for 115 flares of M5 -X7 classes was built. The comparative study of monthly averaged values of several indices of solar activity in current cycle 24: the relative sunspot numbers (SSN), the 10.7 cm radio flux (F 10.7 ), the radiation flux in the Lyman-alpha line (F Lα ), the solar constant (TSI) and the Flare Index (FI) was made.

A statistical analysis of X- class solar flares and their association with the super active regions during solar cycles 23- 24

“…Table 1 shows that more than 50.00 % of solar flares of different intensities (except X2.0 -X2.9 intensity level) occurred during the descending phase of the solar cycle 23. Similar results have also been reported by Le et al (2014) and Bruevich et al (2017) for solar cycles 21-23. This property is associated with the results reported by Le et al (2013a) that the descending phase of solar cycles accounts for most of the occurrences of major geomagnetic storms.…”

“…Recently, Isaeva et al (2020) reported that 78.00% of the solar flares are produced during solar cycle 24 occur predominantly in activity complex (ACs) groups of sunspots based on a relationship between intense solar flares (> M1.0) and activity complex on the Sun. Bruevich et al (2017) also analyzed the large (X-ray class > M1.0) and very large (X-ray class > X1) flares that remain present in solar activity cycle 24 and conclude the flare activity in cycle 24 was significantly weaker than in cycles 21-23, according to the observational inputs (GOES-15, M1 -X7 class) and SDO/EVE (EUVrange). Mohamed et al (2018) reported after analyzing the ARs for the solar cycles 23 and 24 that the high energetic solar flares (X-class flares) become more prominent during the maximum solar activity period and produces at other phases of solar activity, with special emphasis on the declining phases.…”

Solar Flares in the Euv and X-Ray Ranges According by Sdo and Timed Satellite Data

“…В работе [4] проанализированы 115 больших вспышек классов М5 -Х7. Большинство крупных вспышек произошло в фазе подъема и в максимуме 24 цикла.…”

Classification of Solar Flares Based on the Maximum Flux in Soft X–rays and on Duration of Flare

“…Then we determine the level FWQM and find the moments t a and t b using a magnitude of the flux at a maximum F max 0.1−0.8 . In Figure 3 geoeffective characteristic of the flare [1,18].…”

“…For 12.07.2012 flare X-ray index XI is equal to XI = 1.4E −4 • 6480 = 0.907(J/m 2 ) (XI0.907E0) and the energy of this flare is equal to E 0.1−0.8 = 0.792J/m 2 . Thus, the value of XI can be successfully used as a preliminary estimate of the total energy E 0.1−0.8 , which in turn is the most important 10 geoeffective characteristic of the flare [1,18].…”