Authors: Maurice Wilson (NCAR HAO), Steve Tomczyk (NCAR HAO), Sarah Gibson (NCAR HAO), Joan Burkepile (NCAR HAO), Giuliana de Toma (NCAR HAO), Ben Berkey (NCAR HAO), Marc Cotter (NCAR HAO), Michael Galloy (NCAR HAO), Enrico Landi (University of Michigan), Lisa Perez-Gonzalez (NCAR HAO)

The mechanism for the storage and release of magnetic energy in coronal mass ejections (CMEs) remains a major unsolved problem of Heliophysics. Thus, observations of the coronal magnetic field before, during, and after the eruption are important both for scientific progress and space weather predictions. We use the newly built Upgraded Coronal Multichannel Polarimeter (UCoMP) instrument from the Mauna Loa Solar Observatory (MLSO) to study the magnetic and thermodynamic morphology of CME precursors and eruptions. With this coronagraph’s 20-cm aperture and field of view extending from 1.05 to 2.0 solar radii, we determine the magnetic field orientation of pre- and post-CME coronal loops using Stokes Q and U parameters as derived from the linearly polarized radiation observed from the Fe XIII 1074 nm spectral line. To ascertain the density, temperature, and ionization distribution of the hot plasma, we compare and contrast the structures seen at 1074 nm with the coronal features observed by UCoMP at the Fe X 637 nm line, the Fe XV 706 nm line, the Fe XI 789 nm line, and the Fe XIII 1079 nm line. In this study, we use several CME precursors and eruptions as examples for showcasing the unique capabilities of UCoMP, which will inform the future of ground-based coronograph polarimeter observations that will eventually be performed with the COronal Solar Magnetism Observatory (COSMO).