HR: 0800h
AN: SM21A-0448 [Abstracts]
TI: Ionospheric and Solar Plasmas in Geospace Storms
AU: * Moore, T E
EM: thomas.e.moore@nasa.gov
AF: NASA's Goddard Space Flight Center, Lab for Extraterrestrial Physics
Code 692, Greenbelt, MD 20771
United States
AU: Fok, M H
EM: mei-ching.fok@nasa.gov
AF: NASA's Goddard Space Flight Center, Lab for Extraterrestrial Physics
Code 692, Greenbelt, MD 20771
United States
AU: Delcourt, D C
EM: dominique.delcourt@cetp.ipsl.fr
AF: Centre D'etudes des Environnements Terrestre et Planetaire, 4, Ave de Neptune, St. Maur, DC 94107
France
AU: Fedder, J A
EM: fedder@ppdmail.nrl.navy.mil
AF: George Mason University, 4400 University Dr., Fairfax, VA 22030
United States
AU: Liemohn, M W
EM: liemohn@engin.umich.edu
AF: University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109
United States
AU: Slinker, S P
EM: slinker@ppdmail.nrl.navy.mil
AF: Naval Research Laboratory, 4400 Overlook Dr. SW, Washington, DC 20375
United States
AB:
We consider the formation of ring current plasmas in the inner magnetosphere in moderately active conditions that
precondition the plasma sheet and ring current-like region for full fledged geospace storms. We seek to better understand
recent IMAGE energetic neutral atom observations of the ring current, showing that proton injection is relatively smooth and
continuous, while O+ injection is episodic in close association with multiple substorms. We use a modeling framework of
collisionless test particle motions in magnetospheric fields from a magnetohydrodynamic simulation. The simulation is used to
generate bulk properties and detailed velocity distributions at key locations, for comparison with observations. Particles
are initiated in regions representative of the solar wind proton source upstream of the bow shock, the polar wind proton
source, and the auroral zone enhanced outflows of O+, or
AŸ’'A+ƒ_TAŸƒ_sA,A›AŸ’'A,A›AŸA›A›ƒ_sAªA.AAŸƒ_sA,AªAŸ’'A›ƒ,ªAÝAŸA›A›ƒ_sAªA.ƒ_oauroral
windAŸ’'A+ƒ_TAŸƒ_sA,A›AŸ’'A,A›AŸA›A›ƒ_sAªA.AAŸƒ_sA,AªAŸ’'A,A_AŸƒ_sA,A¨AŸƒ_sA,A«. Trajectories are run up to 24 hours to
assure a complete circumnavigation of the Earth. Results reflect steady growth phase conditions after 45 minutes of southward
interplanetary field, Bz = -5 nT (By=0). Solar wind protons enter the ring current principally through the dawn low
latitude boundary layer, while polar wind protons and auroral wind O+ enter the ring current through the midnight plasma
sheet. Thus, solar wind and ionospheric plasmas take very different transport paths to the ring current region. Accordingly,
they should be expected to respond differently to substorm dynamics of the magnetotail, as recently observed. Polar wind
protons make a minor contribution to ring current pressure under steady conditions, but auroral wind O+ has the potential to
dominate the ring current, when dayside outflow is strongly enhanced as it is observed to be during periods of enhanced solar
wind dynamic pressure fluctuations.
UR: http://tem692.gsfc.nasa.gov/public/AGUFM04
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2760 Plasma convection
DE: 2778 Ring current
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting