HR: 16:40h
AN: SM54A-02    [Abstracts]
TI: Phase- and group-velocity in the aurora and its relationship to laboratory plasma wave dispersion
AU: * Semeter, J
EM: jls@bu.edu
AF: Boston University, 8 Saint Mary's St., Boston, MA 02215, United States
AB: The dispersion of inertial-scale Alfven waves in the near-Earth magnetosphere produces field-aligned electron populations with sufficient energy to excite the optical aurora. In these cases, luminous structure should reflect structure in the overlying wave field, thus providing a framework for comparison of auroral imagery with laboratory measurements of Alfven wave dispersion. The challenge lies in collecting images at sufficient cadence and resolution. An analysis of narrow-field video recorded at 50 images/s has revealed two distinct motions in dynamic aurora: a group motion associated with a translating wave packet, and a phase motion associated with the periodic substructure. The latter appears to be consistent with a standing wave pattern. Our working hypothesis is that these ephemeral field patterns result from a rapid drift between the wave source and the background plasma, which would produce Airy-like patterns in the auroral fine structure.
DE: 2704 Auroral phenomena (2407)
DE: 2716 Energetic particles: precipitating
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly