Recovering Photospheric Velocities from Vector Magnetograms by Using a Three-dimensional, Fully Magnetohydrodynamic Model

• Published in: The Astrophysical journal Vol. 674; no. 1; pp. L57 - L60
• Main Authors: Wang, A. H, Wu, S. T, Liu, Yang, Hathaway, D
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 10.02.2008; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; MHD model; Sun: magnetic fields; Magnetogram; Sun : atmospheric motions; MHD; Sun : activity; Magnetic fields; Sun; Atmospheric movements
• ISSN: 1538-4357; 0004-637X; 1538-4357
• DOI: 10.1086/528844

We use a numerical simulation method for recovering the photospheric velocity field from the vector magnetograms. The traditional method is local correlation tracking (LCT), which is based on measuring the relative displacements of features in blocks of pixels between successive white-light images or magnetograms. Within this method, there are a variety of implementations. One of recently developed implementations is induction local correlation tracking (ILCT) as described by Welsch and coworkers. They employ the normal component of magnetic induction equation as a constraint to assure consistent solutions. Our numerical method uses the fully three-dimensional MHD equations to recover the photospheric velocity field with individual vector magnetograms. We compare our method to the ILCT method using NOAA AR 8210 as an example. The differences and similarities are discussed in detail.