To study of preflare plasma.
Short-wave polarization inversion
Fig.10   A study of preflare plasma in flare-productive active region (FPAR) using spectral and
polarization data.  One dimensional scans of AR 9393 (located near the meridian) at several
wavelength is presented. The short-wave polarization inversion is observed one day before power
flare occured at 10h 15m UT in AR 9393.