Chromospheric magnetic field: A comparison of He I 10830 A observations with nonlinear force-free field extrapolation

Abstract

The nonlinear force-free field (NLFFF) modeling has been extensively used to infer the three-dimensional (3D) magnetic field in the solar corona. One of the assumptions in the NLFFF extrapolation is that the plasma beta is low, but this condition is considered to be incorrect in the photosphere. We examine direct measurements of the chromospheric magnetic field in two active regions through spectropolarimetric observations at He I 10830 A, which are compared with the potential fields and NLFFFs extrapolated from the photosphere. The comparisons allow quantitative estimation of the uncertainty in the NLFFF extrapolation from the photosphere. Our analysis shows that observed chromospheric magnetic field may have larger non-potentiality compared to the photospheric magnetic field. Moreover, the large non-potentiality in the chromospheric height may not be reproduced by the NLFFF extrapolation from the photospheric magnetic field. The magnitude of the underestimation of the non-potentiality at chromospheric heights may reach 30-40 degree in shear signed angle in some locations. This deviation may be caused by the non-force-freeness in the photosphere. Our study suggests the importance of the inclusion of measured chromospheric magnetic fields in the NLFFF modeling for the improvement of the coronal extrapolation.

accepted in ApJ

References in corpus (11)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs -- Space-weather HMI Active Region Patches
• Ideal kink instability of a magnetic loop equilibrium
• Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
• Advanced Forward Modeling and Inversion of Stokes Profiles Resulting from the Joint Action of the Hanle and Zeeman Effects
• High-resolution observations of flare precursors in the low solar atmosphere
• Radiative diagnostics in the solar photosphere and chromosphere
• Inference of the chromospheric magnetic field orientation in the Ca II 8542 A line fibrils
• Three-dimensional magnetic structure of a sunspot: comparison of the photosphere and upper chromosphere
• The Height of Chromospheric Loops in an Emerging Flux Region
• Extrapolation of Three-dimensional Magnetic Field Structure in Flare-productive Active Regions with Different Initial Conditions

Cited by in corpus (6)

• A Comparative Study of Solar Active Region 12371 with Data-constrained and Data-driven MHD Simulations
• An Evolution and Eruption of the Coronal Magnetic Field through a Data-Driven MHD Simulation
• Testing a Data-driven Active Region Evolution Model with Boundary Data at Different Heights from a Solar Magnetic Flux Emergence Simulation
• The magnetic topology of the inverse Evershed flow
• Determining the Magnetic Field in the Atmosphere of a Solar Active Region Observed by the CLASP2.1 Sounding Rocket Experiment
• Observational Comparison Between Confined and Eruptive Flares: Magnetohydrodynamics Instability Parameters in a Similar Magnetic Configuration