HR: 1330h
AN: SH42B-0519    [PDF]
TI: Evolution of CME Magnetic Field from the Sun to 1 AU
AU: * Chen, J
EM: chen@ppd.nrl.navy.mil
AF: Plasma Physics Division, Naval Research Laboratory Code 6790, 4555 Overlook Avenue, SW, Washington, DC 20375 United States
AB: Theoretical modeling of the dynamics of coronal mass ejections (CMEs) has progressed to the point where calculated CME acceleration and speed can be quantitatively compared with observed data (e.g., TRACE, MK3, and C1--C2 data). However, the coronal magnetic fields underlying CMEs and their evolution have not been accurately observed. Nevertheless, the magnetic fields of CMEs are indirectly known by {\it in situ} measurements of their presumed interplanetary counterparts. Anticipating improved future measurements and the increasing importance of the CME phenomenon in terms of Sun-Earth connection, we investigate the magnetic fields of CMEs and their evolution to 1 AU. For this purpose, we use a flux-rope model of CMEs that has been extensively tested against observed CMEs with good agreement: (1) we will construct an ensemble of equilibrium flux ropes imbedded in a range of overlying coronal magnetic field; (2) we then allow the flux ropes to erupt and propagate to 1 AU through the corona and the interplanetary medium. We calculate the initial magnetic field of a CME based on its geometrical size (e.g., using the length of a magnetic neutral line obtained from magnetogram data as a proxy for the footpoint separation distance). For various scenarios with or without injection of poloidal magnetic flux into the initial flux rope, we quantitatively determine the range of coronal magnetic field that yields realistic CME dynamics within 30 $R_\odot$ and that results in magnetic fields at 1 AU that are consistent with those of observed magnetic clouds. We discuss predicted magnetic field signatures in the photosphere, the corona, and at 1 AU for a number of distinct scenarios. \noindent Work supported by ONR and NASA
DE: 7509 Corona
DE: 7524 Magnetic fields
DE: 7594 Instruments and techniques
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting