Analyses of magnetic field structures for active region 10720 using a data-driven 3D MHD model

In order to understand solar eruptive events (flares and CMEs) we need to investigate the changes at the solar surface. Thus, we use a data-driven, three-dimensional magnetohydrodynamic (MHD) model to analyze a flare and coronal mass ejection productive active region, AR 10720 on January 15, 2005. The measured magnetic field from Big Bear Solar Observatory (BBSO) digital vector magnetograph (DGVM) was used to model the non-potential coronal magnetic field changes and the evolution of electric current before and after the event occurred. The numerical results include the change of magnetic flux (Φ), the net electric current (IN), the length of magnetic shear of the main neutral line (Lss), the flux normalized measure of the field twist (α=μINΦ) with μ being the magnetic permeability. The current helicity (Hc) injected into the corona and the photospheric surface velocity are also computed. The characteristic parameters of the buildup process before the event and the decay process after the event are investigated and the amount of magnetic energy converted to drive the event is estimated.