Authors: Daniel Mendoza (CU Boulder, LASP) Steven Cranmer ( CU Boulder, LASP)

There are many methods available for extrapolating the Sun’s magnetic field from the photosphere to the heliosphere, such as the classic Potential Field Source Surface method (PFSS) and 3D-MHD simulations. These two methods represent extreme cases of trade-offs between physical realism and computational speed. Specifically, PFSS becomes the method of choice for space weather predictions due to its efficient implementation and inexpensiveness, but it fails to accurately recreate coronal streamers and match total solar eclipse observations. MHD simulations are computationally expensive and complex, but they more accurately depict the magnetic field in the corona, albeit not perfectly. 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 magnetofriction method from Rice & Yeates, make quantitative comparisons with field-line directions observed during a solar cycle’s worth of total eclipses and identify optimal parameters for the extrapolation. In addition, we plan to trace magnetic fields 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 hope this will 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.