AN OVERVIEW OF EXISTING ALGORITHMS FOR RESOLVING THE 180DEGREE AMBIGUITY IN
VECTOR MAGNETIC FIELDS: QUANTITATIVE TESTS WITH SYNTHETIC DATA 

Thomas Metcalf Submitted: 20060601 10:12
We report here on the present stateoftheart in algorithms used for resolving
the 180^{circ} ambiguity in solar vector magnetic field measurements. With
present observations and techniques, some assumption must be made about the
solar magnetic field in order to resolve this ambiguity. Our focus is the
application of numerous existing algorithms to test data for which the correct
answer is known. In this context, we compare the algorithms quantitatively and
seek to understand where each succeeds, where it fails, and why. We have
considered five basic approaches: comparing the observed field to a reference
field or direction, minimizing the vertical gradient of the magnetic pressure,
minimizing the vertical current density, minimizing some approximation to the
total current density, and minimizing some approximation to the field's
divergence. Of the automated methods requiring no human intervention, those
which minimize the square of the vertical current density in conjunction with
an approximation for the vanishing divergence of the magnetic field show the
most promise.
Authors: Metcalf, Leka, Barnes, Lites, Georgoulis, Pevtsov, Gary, Jing, Balasubramaniam, Li, Liu, Wang, Abramenko, Yurchyshyn, Moon
Projects: None

Publication Status: Solar Physics, In Press
Last Modified: 20060601 20:43




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