The Evolutional Characteristics of Magnetic and Velocity Fields in the Photosphere and Chromosphere and the Relation to the Large Flares in AR6659

AR6659 is one of the most Important active region, which erupted the strongest energy events in Cycle 22. The two-dimensional configuration of the region and the evolutional characteristics of the magnetic and velocity fields of the region are analysed in this paper using the photospheric and chromospheric fine structure pictures of Yunnan Observatory and the magnetic field and velocity field data of Beijing Astronomical Observatory. The four large flares occured at the area of N-polarity with the large magnetic field gradient near the neutral line and the red-shift-area of velocity field in the chromospheric. The off-band observation shown that the material of the flares moved forward to the red end. The flare waves propagated along the horizontal field and stimulated inductive flares at the distance of about 100 thousand km from the sunspot group. There were often flare loops between original flares and inductive ones. In addition, the macroscopic instability of the plasma in the active region before the flare eruption is discussed from the point of view of the evolutional characteristics.