Optimization of Coronal Magnetic Field Models Using STEREO/COR-1 Coronagraph Images

Abstract:

Coronal magnetic field models are key for accurate space weather forecasting. Jones et al. have previously presented a method for using quasi-radial features detected in coronagraph images to improve coronal magnetic field models, in which the orientation of features seen in coronagraph images are compared to the projected orientation of the model field. The disagreement is then quantified and used to optimize the coronal magnetic field model. However, previous image-based constraint sets were derived from ground-based images, which limited the number of days for which images could be obtained, and a minimum of a half Carrington rotation was needed to collect constraints throughout the model volume, which neglects evolution of the coronal structure. The COR-1 coronagraphs onboard the twin spacecraft, STEREO A and B, observe the corona from different viewpoints. Early in the mission, the COR-1 instruments provided observations at a five-minute cadence, giving us the opportunity to construct volume-filling constraint sets in shorter time periods. For this reason, we use COR-1 images for this study. The preliminary results of this investigation will be discussed—including comparisons between the COR-1 constraints and the existing K-COR datasets, and the resulting magnetic field model optimizations—as well as plans for future work and improvements to the overall method.