SOLARNET Conference: The Many Scales of the Magnetic Sun

The X1.6 flare observed on 22 October 2014 was one of the strongest flares observed in the complex active region NOAA 12192. We report on observations acquired in the Fe I 617.30 nm and Ca II 854.2nm line profiles by the Interferometric BIdimensional Spectropolarimeter (IBIS) immediately after the peak of the X1.6 flare. We focused on the chromospheric signals and studied the temporal variation of the line of sight (LOS) magnetic field, using the Weak-Field Approximation (WFA). Our results show that stepwise variations occurred at specific locations along the eastern flare ribbon, during the tail of the flare impulsive phase. This result was validated by the STiC inversion of the pixels used for the WFA analysis. We also investigated the photospheric magnetic field obtaining that the LOS magnetic field did not exhibit the same stepwise changes observed in the chromosphere in the selected pixels. Finally, we found no clear evidence of changes along the polarity inversion line around a magnetic polarity intrusion, which is almost cospatial to the area affected by the initial energy release.