Flare Ribbon Expansion and Energy Release
 
Asai, A., Yokoyama, T., Shimojo, M., Masuda, S., Shibata, K.

  We report a detailed examination about the relationship between the
evolution of the H-alpha flare ribbons and the released magnetic
energy during a flare.
  In the H-alpha images, several bright kernels are observed in the
flare ribbons.  We identified the conjugated footpoints, by analyzing
the lightcurves at each H-alpha kernels, and we confirmed the
connectivity from post-flare loop structures observed in the EUV
images.
  Based on the magnetic reconnection model, we also calculated
quantitatively the released energy was by using the photospheric
magnetic field strengths and separation speeds of the fronts of the
H-alpha flare ribbons.  The estimated energy release rate
reconstructed well the bursts in the lightcurves of nonthermal
emission and the spatial distribution of the radiation sources.
  Then, we examined the downward motions which are observed at the
H-alpha kernels.  The "red-asymmetry" is generated by the
precipitation of the nonthermal particles and/or thermal conduction
into the chromospheric plasma.  We found that the stronger the
red-asymmetry is, the brighter the H-alpha kernel is.