L. A. Tarr, D. W. Longcope
The Minimum Current Corona (MCC) model provides a way to estimate stored
coronal energy using the number of field lines connecting regions of positive
and negative photospheric flux. This information is quantified by the net flux
connecting pairs of opposing regions in a connectivity matrix. Changes in the
coronal magnetic field, due to processes such as magnetic reconnection,
manifest themselves as changes in the connectivity matrix. However, the
connectivity matrix will also change when flux sources emerge or submerge
through the photosphere, as often happens in active regions. We have developed
an algorithm to estimate the changes in flux due to emergence and submergence
of magnetic flux sources. These estimated changes must be accounted for in
order to quantify storage and release of magnetic energy in the corona. To
perform this calculation over extended periods of time, we must additionally
have a consistently labeled connectivity matrix over the entire observational
time span. We have therefore developed an automated tracking algorithm to
generate a consistent connectivity matrix as the photospheric source regions
evolve over time. We have applied this method to NOAA Active Region 11112,
which underwent a GOES M2.9 class flare around 19:00 on Oct.16th, 2010, and
calculated a lower bound on the free magnetic energy buildup of ~8.25 x 10^30
ergs over 3 days.
View original:
http://arxiv.org/abs/1202.0075
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