[PEM19-P02] Case study of wavelength 2791.6 Å at flare ribbons by IRIS
The upward and downward motions of chromospheric plasma, which are called chromospheric evaporation and condensation, can be observed during solar flares. The Mg II lines of IRIS provide a good opportunity to study the evolution of chromospheric plasma. Here we particularly focus on the emission property of Mg II triplet line 2791.6 Å in the 2014/10/27 M7.1 flare. To understand the behaviors of Mg II lines, two localized areas with flare brightening feature are selected for analysis. The Mg II h and k lines are also used for comparison. By combining with IRIS, GOES, and RHESSI observations, we find that the 2791.6 Å has different evolution profiles at these two areas. Possible explanations will be discussed in this study.