Modeling of Magnetic Non-Potentiality of Active Region using a 3D Data-Driven Active Region Evolution Model: Seeking Necessary and Sufficient Conditions for Solar Eruption

One of the major interesting problems for space weather forecasting is to have the capability of predicting solar eruptive events. To achieve this goal, we must investigate the evolution of an Active Region. In this presentation, we will present an analysis of magnetic field structures of the productive AR10720 of January 15, 2005 using a data-driven 3D MHD model. The measured magnetic field from Big Bear Solar Observatory (BBSO) digital vector magnetogram (DGVM) was used to model the non-potential magnetic field changes. The numerical results include the change of magnetic flux, the net electric current, the length of magnetic shear of the main neutral line, and the flux normalized measure of the field twist. From these results we found the above four non-potential magnetic parameters increase and decrease before and after solar eruption. In other words, these four parameters are necessary conditions for solar eruption. Then we reveal a particular feature: "the fragmented neutral line". This fragmented neutral line could be interpreted as the variability of the shear angle (angle between the observed and potential horizontal field) along the neutral line. It may be an additional condition for eruption. This suggest that the active region probability of producing an eruption is not only dependent on active region free energy but also on the variability of the shear angle which appears to correspond to the fragmented neutral line