Authors: D.A. Falconer, R.L. Moore, G.A. Gary, S. Balasubramanian
Affiliation: UAH / MSFC / NSSTC
We report further results from our ongoing assessment of magnetogram-based
measures of active-region nonpotentiality (magnetic shear and twist) and size
as predictors of coronal mass ejections (CMEs). From a set of 36 vector magnetograms
of bipolar active regions (Falconer, Moore, & Gary 2004, ApJ, submitted),
we have found that (1) each of our 5 measures of active-region nonpotentiality
has a 75-80% success rate in predicting whether an active region will produce
a CME within 2 days after the magnetogram, (2) the correlation of each of these
measures with CME production in this window is statistically significant (confidence
level > 95%), (3) our measure of active-region size has a 65% success rate
in predicting CMEs in this window, but (4) the correlation between active-region
size and CME productivity is not statistically significant (confidence level
~ 80%). As part of the work under our pending 2003 LWS TR&T proposal, we
will double our sample to ~70 active regions in order to demonstrate a statistically
significant correlation between active-region size and CME productivity, and
to determine whether this correlation is a byproduct of any Sun-produced correlation
between magnetic twist and size of active regions. Since the 2002 LWS Science
Workshop, we have found a measure of active-region nonpotentiality (the length
of strong-gradient neutral line) that can be measured from a line-of-sight magnetogram,
and we have generalized this measure and the corresponding measure from a vector
magnetogram (the length of strong-shear neutral line) so that they can be applied
to multiple-bipole complex active regions as well as to bipolar active regions.
Preliminary results will be presented from application of these two generalized
measures to our sample of bipolar active regions and to a new sample of multiple-bipole
active regions.
This work was funded by NASA through its LWS TR&T Program and its Solar
and Heliospheric Physics SR&T Program, and by NSF through its Space Weather
and SHINE Programs.