Using New Acoustically-Derived Solar Far-Side Magnetic-Flux Maps for Data Assimilation in Flux Transport Models

Abstract:

The Sun's far-side magnetic field is important to space weather forecasting and solar wind modeling, but currently it is not directly observed. The far-side magnetic field can be approximated using (a) flux transport models, which are incapable of predicting growth or new emergence of active regions; (b) conversion from STEREO EUV observations, which are only available for a limited time period; or (c) helioseismic far-side acoustic images, which provide general active region sizes and locations, but not magnetic flux. Recently, Zhao et al.[2019] and Chen et al.[in prep] developed an approach that calculates far-side acoustic images and calibrates them into far-side magnetic-flux maps in near-real-time, using machine-learning and STEREO EUV observations as a bridge. These far-side acoustically-derived magnetic-flux maps are starting to be tested as assimilated data in multiple flux transport models. In this work, we show examples of the results from two different models, and discuss the implications of the fully-assimilated global models of synchronic magnetic flux as operational input for coronal or solar wind models.