Resolving the Azimuthal Ambiguity in Vector Magnetogram Data with the Divergence-Free Condition: Application to Discrete Data |
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| Authors: | A D Crouch G Barnes K D Leka |
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| Institution: | 1.NorthWest Research Associates,Colorado Research Associates Division,Boulder,USA |
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| Abstract: | We investigate how the divergence-free property of magnetic fields can be exploited to resolve the azimuthal ambiguity present
in solar vector magnetogram data, by using line-of-sight and horizontal heliographic derivative information as approximated
from discrete measurements. Using synthetic data we test several methods that each make different assumptions about how the
divergence-free property can be used to resolve the ambiguity. We find that the most robust algorithm involves the minimisation
of the absolute value of the divergence summed over the entire field of view. Away from disk centre this method requires the
sign and magnitude of the line-of-sight derivatives of all three components of the magnetic field vector. |
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