HR: 17:00h
AN: SA24A-05    [Abstracts]
TI: Conversion of Electromagnetic Power to Auroral and Cusp Ion Outflows
AU: * Lotko, W
EM: wlotko@dartmouth.edu
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755 United States
AU: Gagne, J
SA24A-05 AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755 United States
AU: Murr, D
SA24A-05 AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755 United States
AU: Lyon, J
SA24A-05 AF: Dartmouth College, Department of Physics and Astronomy, Hanover, NH 03755 United States
AB: Earthward-directed Poynting fluxes generated in the outer magnetosphere are absorbed at low altitude through Joule heating of the lower ionosphere and the production of particle beams and heat by collisionless wave-particle interactions. Satellite observations indicate that field-aligned Poynting fluxes flowing near the dayside and nightside polar cap boundary, in the passband encompassing 6-180 s variability, are almost completely absorbed at low altitude ( Keiling et al., 2003). These regions are also the sites of suprathermal electron precipitation and large ion outflows, which intensify during active periods. We have used the LFM global magnetospheric MHD model ( Lyon et al., 2004), coupled with an empirical model relating outflow to low-altitude field-aligned Poynting and electron precipitation fluxes ( Strangeway et al., 2005), to study the causal forcing of auroral ion outflows and bulk characteristics of their evolution and fate in the magnetosphere. We find, for example, for a relatvely quiet interval, that the auroral outflow is a minor constituent of the total magnetospheric and magnetotail plasma; at the same time, it appears to be the dominant source of plasma within geostationary orbit. Keiling et al., The global morphology of wave Poynting flux: Powering the aurora, Science, 299, 383, 2003. Lyon et al., The Lyon-Fedder-Mobarry (LFM) global MHD magnetospheric simulation code, J. Atmos. Solar-Terr. Phys., 66, 1333-1350, 2004. Strangeway et al., Factors controlling ionospheric outflows as observed at intermediate altitudes, J. Geophys. Res., 110, A03221, doi:10.1029/2004JA010829, 2005.
DE: 2409 Current systems (2721)
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2704 Auroral phenomena (2407)
DE: 2706 Cusp
DE: 2736 Magnetosphere/ionosphere interactions (2431)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005