Evolution of Vertical Electric Currents and Flares in An Active Region

In this paper, solar active region (AR)6891 is studied.The long-term temporal (over a 8-day period)relationahip between vertical current evolution and flare are examined.We found that the day-to-day variation of the flare number in the active region is more closly associated with the variation of net current intensity than that of total current intensity.The increase in negative current in the weak following polarity area is due to the reduction in negative current in the strong preceding area.