Title: Reversal of Magnetic Shear as a Trigger Mechanism of Solar Flares

Author_list: K.Kusano, T.Maeshiro, T.Yokoyama, and T.Sakurai

Abstract: Based on the three-dimensional numerical simulations, we
propose a new model of solar flare trigger mechanism, that the reversal
of magnetic shear near magnetic neutral line may lead to the onset of
solar flares. The simulation results clearly demonstrate that the
resistive tearing mode instability slowly growing on the shear inversion
layer can consequently cause the collapse of magnetic arcade and the
sudden release of magnetic energy. Also the formation of sigmoid-like
structure in pre-flare phase can be explained by this new model. The
prediction of the model was carefully examined using the vector
magnetograms observed by Solar Flare Telescope at National Astronomical
Observatory in Japan.