HR: 0800h
AN: SM21A-0452    [Abstracts]
TI: The Origin and Evolution of Deep Plasmaspheric Notches
AU: * Gallagher, D L
EM: dennis.l.gallagher@nasa.gov
AF: NASA Marshall Space Flight Center, NSSTC/SD50 320 Sparkman Drive, Huntsville, AL 35805 United States
AU: Adrian, M L
EM: mark.l.adrian@msfc.nasa.gov
AF: University of Alabama in Huntsville, NSSTC/SD50 320 Sparkman Drive, Huntsville, AL 35805 United States
AU: Liemohn, M W
EM: liemohn@umich.edu
AF: University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 United States
AB: Deep plasmaspheric notches can extend over more than 2 RE in radial distance and 3 hours MLT in the magnetic equatorial plane. They appear to be among the largest evacuated features in the exterior plasmaspheric boundary. They can last for days and exhibit varying structure. It appears the origin of notches is shared by low-density channels that result from entrainment of the plasmaspheric convection plume during storm-time recovery. Notches rather than channels result from differences in the location and population of the plume due to differences in the strength of the storm-time convection electric field. Strong convection tends to result in low-density channels, while weaker convection and limited erosion results in notches. Over the 18 events in 2000 have been analyzed. Among these events, notches were found to drift as slowly as 72% of corotation. In only one case was a notch found to drift at the corotation rate with measurement error. On average, notches drift at about 21.5 hours per day or 90% of the corotational rate. Notches also sometimes exhibit interior structures, in particular what appears to be an extended "finger" of dense plasma that forms a W-like feature in IMAGE/EUV images when viewed from Earth-center. Evidence exists such features may be caused by localized, small-scale potential structures caused by injected ring current plasma.
DE: 2730 Magnetosphere--inner
DE: 2760 Plasma convection
DE: 2768 Plasmasphere
DE: 2778 Ring current
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting