Applying the Weighted Horizontal Magnetic Gradient Method to a Simulated Flaring Active Region

Abstract

Here, we test the weighted horizontal magnetic gradient (W G M ) as a flare precursor, introduced by Korsós et al. (2015), by applying it to a magnetohydrodynamic (MHD) simulation of solar-like flares (Chatterjee et al. 2016).The pre-flare evolution of the W G M and the behavior of the distance parameter between the area-weighted barycenters of opposite polarity sunspots at various heights is investigated in the simulated δ-type sunspot. Four flares emanated from this sunspot. We found the optimum heights above the photosphere where the flare precursors of the W G M method are identifiable prior to each flare. These optimum heights agree reasonably well with the heights of the occurrence of flares identified from the analysis of their thermal and Ohmic heating signatures in the simulation. We also estimated the expected time of the flare onsets from the duration of the approaching-receding motion of the barycenters of opposite polarities before each single flare. The estimated onset time and the actual time of occurrence of each flare are in good agreement at the corresponding optimum heights. This numerical experiment further supports the use of flare precursors based on the W G M method.

Flare-productive active regions

“…The strong cancellation between the two spots manifests as a series of flare eruptions with magnitudes comparable to GOES C- and B-class events (Korsós et al. 2018 ). Through the creation of a -spot and the flaring activity, they observed the repeated formation of cool dense filaments above the PIL and the ejection of helical flux ropes.…”

Solar Flare Prediction Using Magnetic Field Diagnostics above the Photosphere

“…Motivated by the case studies of Korsós et al (2018aKorsós et al ( , 2018b, we now extend the application of the WG M method to more ARs by constructing a data catalog of sunspots using 3D PF and NLFFF extrapolations. An extrapolation example from the collected data catalog is shown in Figure 1.…”

“…They introduced and applied two flare precursors, part of the WG M method (Korsós et al 2019): one is related to the inverted V-shape feature of the WG M proxy and the other is obtained from the U-shape of the so-called distance parameter prior to each investigated flare at a certain height range in the solar atmosphere. Korsós et al (2018a) further conjectured the existence of the so-called optimal height, where the U-shape manifests itself earlier and reaches its minimum value earlier than in the photosphere. In their modeling study it was also shown that these optimal heights agreed reasonably well with the heights of flare occurrence identified by an analysis of thermal and ohmic heating signatures enabled by the magnetohydrodynamic (MHD) simulations of Korsós et al (2018a).…”

“…Korsós et al (2018a) further conjectured the existence of the so-called optimal height, where the U-shape manifests itself earlier and reaches its minimum value earlier than in the photosphere. In their modeling study it was also shown that these optimal heights agreed reasonably well with the heights of flare occurrence identified by an analysis of thermal and ohmic heating signatures enabled by the magnetohydrodynamic (MHD) simulations of Korsós et al (2018a). Next, for NOAA AR 11429, Korsós et al (2018b) used PF extrapolation to construct the 3D magnetic field above the photosphere and studied the preflare evolution of this AR prior to two M-class flares.…”

“…Another potentially insightful approach may be the numerical simulation of AR from the subphotosphere to their emergence and evolution in the lower solar atmosphere. With the aim of testing flare prediction with simulated data, a flaring AR with δ-sunspots was modeled by Korsós et al (2018a). They introduced and applied two flare precursors, part of the WG M method (Korsós et al 2019): one is related to the inverted V-shape feature of the WG M proxy and the other is obtained from the U-shape of the so-called distance parameter prior to each investigated flare at a certain height range in the solar atmosphere.…”