An Overview of Existing Algorithms for Resolving the 180° Ambiguity in Vector Magnetic Fields: Quantitative Tests with Synthetic Data

By T. Metcalf, K. Leka, G. Barnes, B. Lites, Manolis K. Georgoulis, A. Pevtsov, K. Balasubramaniam, G. A. Gary, J. Jing, Jing Li and 5 more. 2006

269 citations recorded by the source corpus.

Subfields: Artificial Intelligence, Astronomy and Astrophysics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/7f46ca7b322fe494c437075da77ba93b61b521e8

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Citations in the corpus

How Should One Optimize Nonlinear Force-Free Coronal Magnetic Field Extrapolations from SDO/HMI Vector Magnetograms? (2012, methodology): “The 180◦ azimuthal ambiguity in the transverse field is resolved by an improved version of the minimum energy algorithm (Metcalf, 1994; Metcalf et al., 2006; Leka et al., 2009).”
COEXISTING FLUX ROPE AND DIPPED ARCADE SECTIONS ALONG ONE SOLAR FILAMENT (2010, background): “…the observed and modeled magnetic fields, the vertical gradient of the magnetic pressure, the vertical current density, some approximations to the total current density or the field’s divergence, or the combination of the quantities listed above (Metcalf et al. 2006, and references therein).”
Resolving the 180° Ambiguity in Solar Vector Magnetic Field Data: Evaluating the Effects of Noise, Spatial Resolution, and Method Assumptions (2009, methodology): “The Minimum Energy Method The Minimum Energy method (Metcalf, 1994; Metcalf et al., 2006) was a workin-progress by our late colleague Dr. Thomas R. Metcalf, and additional options and features had been recently added or were being tested at the time of his death.”
The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance (2014, methodology): “This method has been shown to be among the best performing on a wide range of tests on synthetic data for which the answer is known (Metcalf et al., 2006; Leka et al., 2009).”
Photospheric Magnetic Field Properties of Flaring versus Flare-quiet Active Regions. IV. A Statistically Significant Sample (2007, methodology): “…of the University of Hawai‘i approach, which minimizes the vertical current and the divergence of the mag- netic field (Canfield et al. 1993; Metcalf et al. 2006): the first resolution is based on a linear force-free field constructed using the image-plane data and the force-free…”
Nonlinear Force-free Field Modeling of a Solar Active Region around the Time of a Major Flare and Coronal Mass Ejection (2007, methodology): “The algorithm applied includes the enhancements described in Metcalf et al. (2006) and was the top-performing automated method among those compared in that same study.”
EVOLUTION OF MAGNETIC FIELD AND ENERGY IN A MAJOR ERUPTIVE ACTIVE REGION BASED ON SDO/HMI OBSERVATION (2011, methodology): “The 180◦ azimuthal ambiguity in the transverse field is resolved by an improved version of the “minimum energy” algorithm (Metcalf 1994; Metcalf et al. 2006; Leka et al. 2009).”
Comparison of Line-of-Sight Magnetograms Taken by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager and Solar and Heliospheric Observatory/Michelson Doppler Imager (2012, methodology): “The Stokes parameters [I, Q, U, V ] are computed from those measurements, and are further inverted (Borrero et al., 2011) and SOLA: hmilosmag_v0315.tex; 16 March 2012; 9:08; p. 2 disambiguated (Metcalf et al., 2006; Leka et al., 2009) to retrieve the vector magnetic field.”
Driving major solar flares and eruptions: A review (2008, background): “Problems abound (see, e.g., Klimchuk et al. 1992, McClymont et al. 1997, Schrijver et al. 2006a, Metcalf et al. 2006, Metcalf et al. 2008; Schrijver et al. 2008, and DeRosa et al. 2009): nonlinear force-free field (NLFFF) models or virial-theorem applications based on photospheric vector fields…”
The Helioseismic and Magnetic Imager (HMI) Investigation for the Solar Dynamics Observatory (SDO) (2012, methodology): “A further product is computed as the final vector field by applying a field direction disambiguation technique, since the Stokes parameters cannot distinguish the polarity of the component of the field normal to the line-of-sight (Metcalf, 1994; Metcalf et al., 2006; Leka et al., 2009).”
Solar Force-free Magnetic Fields (2012, methodology): “Let us remark that Metcalf et al. (2006) introduced more comparison metrics, which, however, do not influence the relative rating of the discussed ambiguity algorithms.”
A CRITICAL ASSESSMENT OF NONLINEAR FORCE-FREE FIELD MODELING OF THE SOLAR CORONA FOR ACTIVE REGION 10953 (2009, methodology): “…algorithms to do this, we chose as an alternative to AZAM to employ the automated University of Hawai‘i Iterative Method (UHIM) (Canfield et al. 1993) because it has been used extensively in the literature and also scored highly amongst other ambiguity resolution algorithms (Metcalf et al. 2006).”