Analyses of Vector Magnetograms

Abstract

Abstract(1) Current techniques may now permit an acceptable resolution of the 180 degree ambiguity in determining the direction of transverse fields. (2) The non-potentiality of active regions can be described by parameters of angular shear, source field, line-of-sight current, force-free factor and force-free current. A 2-dimensional description of angular shear is necessary, and an alternative, FFT method of calculating the line-of-sight current seems recommendable. (3) For a sampling region, the degree of non-potentiality quantified by all the parameters shows great enhancement right before a 1M flare, and reduces somehow during the flare. (4) A highly intermittent distribution of force-free factor with fully mixed signs is obtained, consistent with a theoretical approach.