Nonlinear Force-Free Magnetic Field Fitting to Coronal Loops with and without Stereoscopy

Abstract

We developed a new nonlinear force-free magnetic field (NLFFF) forward-fitting algorithm based on an analytical approximation of force-free and divergence-free NLFFF solutions, which requires as input a line-of-sight magnetogram and traced 2D loop coordinates of coronal loops only, in contrast to stereoscopically triangulated 3D loop coordinates used in previous studies. Test results of simulated magnetic configurations and from four active regions observed with STEREO demonstrate that NLFFF solutions can be fitted with equal accuracy with or without stereoscopy, which relinquishes the necessity of STEREO data for magnetic modeling of active regions (on the solar disk). The 2D loop tracing method achieves a 2D misalignment of ${\mu }_2=2.7^{\circ }\pm 1.3^{\circ }$ between the model field lines and observed loops, and an accuracy of $\approx 1.0$ for the magnetic energy or free magnetic energy ratio. The three times higher spatial resolution of TRACE or SDO/AIA (compared with STEREO) yields also a proportionally smaller misalignment angle between model fit and observations. Visual/manual loop tracings are found to produce more accurate magnetic model fits than automated tracing algorithms. The computation time of the new forward-fitting code amounts to a few minutes per active region.

ApJ, Febr 2013, (in press), 11 Figures

References in corpus (4)

• Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection
• A self-consistent nonlinear force-free solution for a solar active region magnetic field
• Guiding Nonlinear Force-Free Modeling Using Coronal Observations: First Results Using a Quasi Grad-Rubin Scheme
• First 3D Reconstructions of Coronal Loops with the STEREO A+B Spacecraft: IV. Magnetic Modeling with Twisted Force-Free Fields

Cited by in corpus (25)

• Solar Force-free Magnetic Fields
• Global Energetics of Solar Flares: I. Magnetic Energies
• Magnetic Field Extrapolations in the Corona: Success and Future Improvements
• Probing the Physics of the Solar Atmosphere with the Multi-slit Solar Explorer (MUSE): II. Flares and Eruptions
• The Magnetic Field of Active Region 11158 During the 2011 February 12-17 Flares : Differences between Photospheric Extrapolation and Coronal Forward-Fitting Methods
• The Vertical Current Approximation Nonlinear Force-Free Field Code - Description, Performance Tests, and Measurements of Magnetic Energies Dissipated in Solar Flares
• Optimization of Curvi-Linear Tracing Applied to Solar Physics and Biophysics
• Solar Flare Arcade Modelling: Bridging the gap from 1D to 3D Simulations of Optically Thin Radiation
• Tracing the Chromospheric and Coronal Magnetic Field with AIA, IRIS, IBIS, and ROSA Data
• Comparison of Two Coronal Magnetic Field Models for Reconstructing a Sigmoidal Solar Active Region With Coronal Loops
• Towards a Quantitative Comparison of Magnetic Field Extrapolations and Observed Coronal Loops
• Solar Sector Structure
• Blind Stereoscopy of the Coronal Magnetic Field
• Application of a magnetic-field-induced transition in Fe X to solar and stellar coronal magnetic field measurements
• Nonlinear force-free coronal magnetic stereoscopy
• Helical Twisting Number and Braiding Linkage Number of Solar Coronal Loops
• Torsional Alfvénic Oscillations Discovered in the Magnetic Free Energy During Solar Flares
• On the Area Expansion of Magnetic Flux-Tubes in Solar Active Regions
• Global Energetics of Solar Flares. IX. Refined Magnetic Modeling
• Optimizing Global Coronal Magnetic Field Models Using Image-Based Constraints
• Toward a fast and consistent approach to model solar magnetic fields in multiple layers
• Tracing the magnetic field topology of the quiet corona using propagating disturbances
• Population of Bright Plume Threads in Solar Polar Coronal Holes
• Equilibrium models of coronal loops that involve curvature and buoyancy
• Forward Modeling of Solar Coronal Magnetic Field Measurements Based on a Magnetic-field-induced Transition in Fe X