A New Code for Nonlinear Force-Free Field Extrapolation of the Global Corona

Abstract

Reliable measurements of the solar magnetic field are still restricted to the photosphere, and our present knowledge of the three-dimensional coronal magnetic field is largely based on extrapolation from photospheric magnetogram using physical models, e.g., the nonlinear force-free field (NLFFF) model as usually adopted. Most of the currently available NLFFF codes have been developed with computational volume like Cartesian box or spherical wedge while a global full-sphere extrapolation is still under developing. A high-performance global extrapolation code is in particular urgently needed considering that Solar Dynamics Observatory (SDO) can provide full-disk magnetogram with resolution up to $4096\times 4096$. In this work, we present a new parallelized code for global NLFFF extrapolation with the photosphere magnetogram as input. The method is based on magnetohydrodynamics relaxation approach, the CESE-MHD numerical scheme and a Yin-Yang spherical grid that is used to overcome the polar problems of the standard spherical grid. The code is validated by two full-sphere force-free solutions from Low & Lou's semi-analytic force-free field model. The code shows high accuracy and fast convergence, and can be ready for future practical application if combined with an adaptive mesh refinement technique.

Accepted by ApJ, 26 pages, 10 figures

References in corpus (5)

• Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
• The solar magnetic field
• Nonlinear force-free modeling of the solar coronal magnetic field
• Computing nonlinear force-free fields in spherical geometry
• Magnetic Connectivity between Active Regions 10987, 10988, and 10989 by Means of Nonlinear Force-Free Field Extrapolation

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• Nonlinear Force-Free Field Extrapolation of a Coronal Magnetic Flux Rope Supporting a Large-Scale Filament from Photospheric Vector Magnetogram
• Preprocess the Photospheric Vector Magnetograms for NLFFF Extrapolation using a Potential Field Model and an Optimization Method
• Comparison of Two Coronal Magnetic Field Models for Reconstructing a Sigmoidal Solar Active Region With Coronal Loops
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• Efficient, Divergence-Free, High Order MHD on 3D Spherical Meshes with Optimal Geodesic Meshing
• APSARA: A multi-dimensional unsplit fourth-order explicit Eulerian hydrodynamics code for arbitrary curvilinear grids
• Testing a Solar Coronal Magnetic Field Extrapolation Code with the Titov-Demoulin Magnetic Flux Rope Model