Flare Productivity of Major Flaring Solar Active Regions: A Time-Series Study of Photospheric Magnetic Properties

Abstract

A solar active region (AR) that produces at least one M-or X-class major flare tends to produce multiple flares during its passage across the solar disk. It will be interesting if we can estimate how flare-productive a given major flaring AR is for a time interval of several days, by investigating time series of its photospheric magnetic field properties. For this, we studied 93 major flaring ARs observed from 2010 to 2016 by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). More specifically, for each AR under study, the mean and fluctuation were calculated from an 8-day time series of each of 18 photospheric magnetic parameters extracted from the Spaceweather HMI Active Region Patch (SHARP) vector magnetogram products at 12-min cadence. We then compared these with the AR's 8-day flare index, which is defined as the sum of soft X-ray peak fluxes of flares produced in the AR during the same interval of the 8-day SHARP parameter time series. As a result, it is found that the 8-day flare index is well correlated with the mean and/or fluctuation values of some magnetic parameters (with correlation coefficients of 0.6-0.7 in log-log space). Interestingly, the 8-day flare index shows a slightly better correlation with the fluctuation than the mean for the SHARP parameters associated with the surface integral of photospheric magnetic free energy density. Lee et al.We also discuss how the correlation varies if the 8-day flare index is compared with the mean or fluctuation calculated from an initial portion of the SHARP parameter time series.

Magnetic Helicity Flux across Solar Active Region Photospheres: II. Association of Hemispheric Sign Preference with Flaring Activity during Solar Cycle 24

“…On the other hand, a positive correlation exists between the average Φ and the average F idx with the linear PCC = 0.65 (refer to panel (b) of Figure 5). Such correlation of Φ with flaring activity in "individual" ARs has been reported in many previous studies (e.g., Leka & Barnes 2003Park et al 2010;Liu et al 2017;Lee et al 2018), but it is reported here for the first time on this larger spatial scale of the HRs over a much longer period of solar cycle 24. As shown in Figure 5(c), a negative, although weak, correlation appears between the HSP and the average Φ with the linear PCC = −0.36.…”

“…Here N j is the total number of j-class flares assigned to the given AR sample during τ , and M j i is the magnitude (i.e., digit multipliers from 1.0 to 9.9) of the j-class flares. Simply put, F idx refers to the sum of GOES soft X-ray peak fluxes of all flares assigned to the given AR during τ , and it is often considered to measure flare productivity of an AR for a target interval (e.g., Abramenko 2005;Park et al 2010;Lee et al 2018).…”

The characteristics of flare- and CME-productive solar active regions

“…It should be noted in passing that various combinations of the many parameters utilized by Leka et al [2018] performed similarly well, within the error margins. Lee et al [2018] used a Detrended Fluctuation Analysis to remove persistent patterns and quantify the random variations in consecutive non-overlapping segments of time series. The detrended fluctuation and the time series averages were positively correlated with the imminent 8-day flare index.…”

Relationship between Successive Flares in the Same Active Region and SHARP Parameters

“…It also provides a data product named Space-weather HMI Active Region Patch (SHARP), which offers a series of key parameters derived from the magnetic field in ARs (Bobra et al 2014;Hoeksema et al 2014). Lee et al (2018) applied I 8d , the sum of the GOES soft X-ray peak fluxes of flares in the same AR for 8 days, to investigate the correlation between SHARP parameters and flare productivity in time series, concluding that the SHARP parameters are to some extent related to flare productivity. Wang et al (2019) calculated the SHARP parameters in the polarity inversion line area of an AR, and employed a support vector machine algorithm to perform flare prediction with the modified SHARP parameters.…”