The magnetic fields in the solar atmosphere structure the plasma, store free
magnetic energy and produce a wide variety of active solar phenomena, like
flare and coronal mass ejections(CMEs). The distribution and strength of
magnetic fields are routinely measured in the solar surface(photosphere).
Therefore, there is considerable interest in accurately modeling the 3D
structure of the coronal magnetic field using photospheric vector magnetograms.
Knowledge of the 3D structure of magnetic field lines also help us to interpret
other coronal observations, e.g., EUV images of the radiating coronal plasma.
Nonlinear force-free field (NLFFF) models are thought to be viable tools for
those task. Usually those models use Cartesian geometry. However, the spherical
nature of the solar surface cannot be neglected when the field of view is
large. In this work, we model the coronal magnetic field above multiple active
regions using NLFFF extrapolation code using vector magnetograph data from the
Synoptic Optical Long-term Investigations of the Sun survey (SOLIS)/ Vector
Spectromagnetograph (VSM) as a boundary conditions. We compare projections of
the resulting magnetic field lines solutions with their respective coronal
EUV-images from the Atmospheric Imaging Assembly (SDO/AIA) observed on October
11, 2011 and November 13, 2012. This study has found that the NLFFF model in
spherical geometry reconstructs the magnetic configurations for several active
regions which agrees with observations. During October 11, 2011 observation,
there are substantial number of trans-equatorial loops carrying electric
current.Comment: 3 Figures, Submitted to Astrophysics and Space Science Journa
