Nonlinear force-free and potential field models of active-region and global coronal fields during the Whole Heliospheric Interval

Abstract

Between 2008/3/24 and 2008/4/2, the three active regions NOAA active regions 10987, 10988 and 10989 were observed daily by the Synoptic Optical Long-term Investigations of the Sun (SOLIS) Vector Spectro-Magnetograph (VSM) while they traversed the solar disk. We use these measurements and the nonlinear force-free magnetic field code XTRAPOL to reconstruct the coronal magnetic field for each active region and compare model field lines with images from the Solar Terrestrial RElations Observatory (STEREO) and Hinode X-ray Telescope (XRT) telescopes. Synoptic maps made from continuous, round-the-clock Global Oscillations Network Group (GONG) magnetograms provide information on the global photospheric field and potential-field source-surface models based on these maps describe the global coronal field during the Whole Heliospheric Interval (WHI) and its neighboring rotations. Features of the modeled global field, such as the coronal holes and streamer belt locations, are discussed in comparison with extreme ultra-violet and coronagraph observations from STEREO. The global field is found to be far from a minimum, dipolar state. From the nonlinear models we compute physical quantities for the active regions such as the photospheric magnetic and electric current fluxes, the free magnetic energy and the relative helicity for each region each day where observations permit. The interconnectivity of the three regions is addressed in the context of the potential-field source-surface model. Using local and global quantities derived from the models, we briefly discuss the different observed activity levels of the regions.

Accepted for publication in the Solar Physics Whole Heliospheric Interval (WHI) topical issue. We had difficulty squeezing this paper into arXiv's 15 Mb limit. The full paper is available here ftp://gong2.nso.edu/dsds_user/petrie/PetrieCanouAmari.pdf

References in corpus (6)

• Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection
• Nonlinear force-free modeling of the solar coronal magnetic field
• Observational Test of Coronal Magnetic Field Models I. Comparison with Potential Field Model
• A self-consistent nonlinear force-free solution for a solar active region magnetic field
• A Comparative Study of Magnetic Fields in the Solar Photosphere and Chromosphere at Equatorial and Polar Latitudes
• Nonlinear force-free modelling: influence of inaccuracies in the measured magnetic vector

Cited by in corpus (6)

• First 3D Reconstructions of Coronal Loops with the STEREO A+B Spacecraft: IV. Magnetic Modeling with Twisted Force-Free Fields
• Photospheric Magnetic Evolution in the WHI Active Regions
• SIP-IFVM: Efficient time-accurate magnetohydrodynamic model of the corona and coronal mass ejections
• Time-evolving coronal modelling of the solar maximum around the solar storms in May 2024 by COCONUT
• Reconstruction of Coronal Magnetic Fields Using a Poloidal-Toroidal Representation
• A comparison of coronal mass ejection models with observations for two large CMEs detected during the Whole Heliosphere Interval