HR: 13:40h
AN: SM23B-01 INVITED     [Abstracts]
TI: Steady Magnetospheric Convection: A Review
AU: * Fairfield, D H
EM: Donald.H.Fairfield@nasa.gov
AF: NASA Goddard Space Flight Center, Code 695 NASA/GSFC, Greenbelt, MD 20771 United States
AB: On occasion, solar wind energy enters Earth's magnetosphere yet the common discrete energy-dissipation events known as magnetospheric substorms fail to occur. During these times, the magnetotail assumes a configuration where earthward of about 12 Re the tail remains in a stretched tail-like state with a thin current sheet similar to the substorm growth phase. At the same time the more distant tail attains a more relaxed configuration with a thick plasma sheet, weak lobe field and enhanced northward Bz, similar to the substorm recovery phase. Simultaneously, (1) auroral zone currents remain strong and assume a two cell DP 2 convection pattern; (2) the auroral oval is wide and optically active, particularly at its poleward and equatorward edges; (3) polar cap area remains constant and energetic particle boundaries are stable, (4) earthward plasma flow persists near the center of the tail as implied by the name steady magnetospheric convection (SMC) except that it occurs on a time scale of minutes and the flow remains bursty. These small scale flows in the tail correspond to auroral streamers that form near the poleward boundary of the oval and propagate equatorward in a few minutes time. Although SMC events have some substorm-like characteristics, such as Pi2's, particle injections and region 1-type field aligned currents with their associated westward ionospheric currents, such phenomena occur on much shorter time and spatial scales and with much smaller amplitudes than actual substorms. Modeling the global magnetic field for several specific SMC events suggest that a minimum in the equatorial tail field Bz magnitude exists near 12 Re which may correspond to the one known equilibrium field configuration that can avoid the pressure catastrophe that may correspond to substorms. This unique field configuration may permit the return of magnetic flux to the dayside that allows the persistence of the steady state field configuration.
DE: 2704 Auroral phenomena (2407)
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2760 Plasma convection
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting