An observationally constrained 3D potential-field source-surface model for the evolution of longitude-dependent coronal structures

The challenge of creating synoptic maps of the photosphere that reliably reflect conditions at all locations concurrently is a major limitation to progress in this area. White-light coronal images, which contain morphological information about the 3D corona at the solar limb, have been largely overlooked as a resource for constraining or correcting synoptic maps.

We explore a complementary approach to traditional magnetogram-based coronal field solutions that makes use of these images. Applying a modified 3D potential-field source-surface (PFSS) model, we investigate the use of MLSO white-light coronal images for deriving 3D coronal morphology by empirically fitting model solutions with observations only. Applying an iterative technique to coronal image data from the solar minima preceding Cycles 22, 23, and 24, and the ascending phase of Cycle 23, we obtain model solutions as linear combinations of low order and degree spherical harmonics.