Authors: Daniel Mendoza (University of Colorado Boulder), Steven Cranmer (University of Colorado Boulder)

Extrapolation models such as Potential Field Source Surface (PFSS) and 3D magnetohydrodynamic (MHD) simulations allow for the tracing of the Sun’s magnetic field lines. Doing so is critical for the ability to predict solar weather and use what we know from the Sun to gain insight into how other stellar systems may impact exoplanets. PFSS and MHD represent extreme cases of trade-offs between physical realism and computational speed. There are methods attempting to bridge the gap between PFSS and MHD (e.g., techniques using current sheets or magnetofrictional relaxation), but their relative agreement with coronal field shapes has not been tested comprehensively. In this work, we explore a magnetofrictional method from Rice and Yeates and make quantitative comparisons with field line directions observed during a solar cycle’s worth of total eclipses and identify optimal parameters for the extrapolation (including a radial prescription for the outflow speed based on models that include turbulent dissipation). In addition, we trace magnetic field lines from the heliosphere to the solar surface using several different field-line extrapolation methods and study the relative variances in the derived footpoint locations. We intend for this to provide useful constraints on the uncertainties inherent in the footpoint-tracing process that is often used to identify coronal source regions of solar wind parcels measured with in-situ instrumentation.