Journal ArticleDOI
An Overview of Existing Algorithms for Resolving the 180° Ambiguity in Vector Magnetic Fields: Quantitative Tests with Synthetic Data
Thomas R. Metcalf,K. D. Leka,Graham Barnes,Bruce W. Lites,Manolis K. Georgoulis,Alexei A. Pevtsov,Krishnan Balasubramaniam,G. Allen Gary,Ju Jing,Jing Li,Yang Liu,Huaning Wang,Valentyna Abramenko,Vasyl Yurchyshyn,Yong-Jae Moon +14 more
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TLDR
In this article, the authors report on the state-of-the-art in algorithms used for resolving the 180° ambiguity in solar vector magnetic field measurements and compare them quantitatively and seek to understand where each succeeds, where it fails and why.Abstract:
We report here on the present state-of-the-art in algorithms used for resolving the 180° 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.read more
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Journal ArticleDOI
Extremely Large Extreme-ultraviolet Late Phase Powered by Intense Early Heating in a Non-eruptive Solar Flare
TL;DR: In this paper, the authors analyzed and modeled an M1.2 non-eruptive solar flare on 2011 September 9, and revealed the existence of a magnetic null point, a fan-spine structure, and two flux ropes embedded in the fan dome.
Journal ArticleDOI
Algorithms of the Potential Field Calculation in a Three-Dimensional Box
TL;DR: In this paper, the potential field inside a three-dimensional box with the normal magnetic field component given on all boundaries is calculated to estimate important quantities related to the magnetic field, such as free energy and relative helicity.
Journal ArticleDOI
Magnetic flux ropes: Fundamental structures for eruptive phenomena
Tahar Amari,J. J. Aly +1 more
TL;DR: In this article, the authors consider the possibility to show the presence of a twisted magnetic flux ropes (TFR) in a pre-eruptive configuration by using a model along with observational informations provided by a vector magnetograph and discuss the issues of the energy and helicity contents of an erupting configuration.
Journal ArticleDOI
Plasma Motions and Turbulent Magnetic Diffusivity of Active Region AR 12158 Using a Minimum Energy Functional and Non-Force-Free Reconstructions of Vector Magnetograms
Benoit Tremblay,Alain Vincent +1 more
TL;DR: Hu et al. as discussed by the authors presented a generalization of the resistive minimum energy fit (MEF-R) for non-force-free (NFF) magnetic fields, which can be used as boundary conditions in data-driven simulations or in data assimilation.
Journal ArticleDOI
Automated Driving for Global Nonpotential Simulations of the Solar Corona
TL;DR: In this paper , an automated technique for active region emergence in coronal magnetic field models, based on the inversion of the electric field locally from a single line-of-sight magnetogram for each region.
References
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The Solar Oscillations Investigation — Michelson Doppler Imager
Philip H. Scherrer,R. S. Bogart,R. I. Bush,J. T. Hoeksema,Alexander G. Kosovichev,Jesper Schou,W. Rosenberg,L. Springer,T. D. Tarbell,A. M. Title,C. J. Wolfson,I. Zayer +11 more
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