p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica}Rapid transformations of sunspot structures usually can be observed duringthe flare eruption. However, it is still controversial that if the transformations areinduced by the flare eruption or not. In this paper, we present the observations andanalysis of the reversal transformations of sunspot in two flare events, proving thatthe coronal flare eruption can affect the sunspot structures in the photosphere.In the case of the flare SOL2015-06-25T08:16 (M7.9), we reported that theoriginally decayed penumbra showed a sudden reappearance along the flaring polarityinversion line (PIL). On the other hand, the small umbra, where the reappearingpenumbra rooted, had a sudden northeastward motion, toward the northpart of a large sunspot located in the other side of PIL. These observations canbe well understood as a result of coronal fields contraction, which can be deducedfrom the nonlinear force-free field extrapolation model.In the case of the flare SOL2013-11-03T05:22 (M5.0), we reported that a largepenumbral area experiencing two kinds of transformations during the eruption.One penumbral segment decayed and transformed into a small pore when sweptby the flare ribbon. At the same time, an adjacent penumbral segment expandedpermeating into the granular area along the flaring magnetic polarity inversion line.EUV and X-ray observations indicated that the penumbral enhancement area wasclose to the flare center, while the penumbral decay area was on the relatively outerside. By tracking the magnetic motions and local magnetic field changes, we foundthat the magnetic transformations within two regions were totally different duringthe flare. The central penumbral enhancement area was accompanied by the fieldcollapsing down, whereas the outer penumbral decay area was associated with thefield lifting up towards the upper flare center. Particularly, following the upliftmotion of the magnetic fields in the outer region, the magnetic flux in the decayingpenumbra decreased and that in the forming pore subsequently increased. Theseresults implied that the rearrangement of magnetic field during the flare would bethe reason that resulted in the variations of the sunspot structures.
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