Evolution of Magnetic Flux Rope in the Active Region NOAA 9077 on 14 July 2000

The finite energy force-free magnetic fields of the active region NOAA 9077 on 14 July 2000 above the photosphere were reconstructed. We study the evolution of the 3D magnetic field structures in AR 9077 and compare the reconstructed field lines with TRACE EUV 171 Å flare loops during the flare maximum, which confirms the process that flaring loops extended from lower sheared level to higher arcades. We also demonstrate the 3D magnetic field evolution before the 3B/X5.7 flare on 14 July and the magnetic structure after the flare on 15 July. This shows that the helical magnetic structures were significantly changed, suggesting that the flux rope was indeed erupted during the energetic flare at 10:24 UT on 14 July.