A prospective method for predicting coronal mass ejections from vector magnetograms

Two quantitative measures of the global nonpotentiality of predominantly bipolar active regions are explored for their usefulness as indicators of whether an active region is likely to produce coronal mass ejections (CMEs). The two measures, length of strong-field strong-shear main neutral line (L-SS) and global net current (I-N), are obtained directly from vector magnetograms of the regions. From measurements of L-SS and I-N in four active regions for which the global nonpotentiality and CME productivity are assessed independently of L-SS and I-N, it appears that L-SS and I-N are each a useful indicator of an active region's likely CME productivity. The results also suggest that L-SS and I-N may be more reliable predictors of the CME productivity of active regions than is the presence or absence of sigmoidal structure in coronal X-ray images of the regions and that there might be threshold values of L-SS and I-N above which CME production is likely and below which CME production is unlikely. While these results need to be certified by an expansion of this pilot study to more active regions, they show the promise of L-SS and I-N as quantitative measures of global nonpotentiality for CME prediction.