Measuring Active-Region Global Magnetic Twist for Prediction of Earthward Coronal Mass Ejections and their Geoeffectiveness

University Of Alabama In Huntsville, Huntsville AL

Investigators

Abstract

Elimination of the need for painstaking alignment of coronal X-ray images with vector magnetograms and for expert scrutiny of the X-ray structure of the core field is an important step toward practical operational forecasting of Earth-directed Coronal Mass Ejections (CMEs) and their geoeffectiveness from vector magnetographs. An empirical evaluation of the reliability of core magnetic field determinations based upon three distinct methods will be carried out. These magnetogram-alone methods of resolving the 180 degree ambiguity in the direction of the transverse magnetic field in cases of strong shear and twist will be tested with a set of 20-30 active regions where coeval X-ray data can be used to define the field direction. The active regions that have strongly sheared core magnetic fields are most likely to produce CMEs, and knowledge of the orientation of this core field is important for anticipating the direction of the Interplanetary Magnetic Field (IMF) at Earth.