HR: 09:30h
AN: SA41B-07 INVITED     [Abstracts]
TI: Magnetospheric and Ionospheric Electric Fields During Superstorms
AU: * Wolf, R A
EM: rawolf@rice.edu
AF: Rice University, Physics and Astronomy Dept., Rice University MS108, P.O. Box 1892, Houston, TX 77251-1892 United States
AU: Hill, T W
EM: hill@rice.edu
AF: Rice University, Physics and Astronomy Dept., Rice University MS108, P.O. Box 1892, Houston, TX 77251-1892 United States
AU: Sazykin, S
EM: sazykin@rice.edu
AF: Rice University, Physics and Astronomy Dept., Rice University MS108, P.O. Box 1892, Houston, TX 77251-1892 United States
AU: Hairston, M R
EM: hairston@utdallas.edu
AF: University of Texas at Dallas, W.B. Hanson Center for Space Sciences, P.O.Box 830688 FO22, Richardson, TX 75083-0688 United States
AB: In the strongest magnetic storms, magnetospheric and ionospheric electric fields develop in ways that clearly differ from linear extrapolations from normal behavior. We will review observations and possible theoretical explanations of several specific superstorm-electric-field phenomena that have received considerable research attention recently. The observed polar-cap potential drop saturates at 200-250 kV, rather than increasing linearly with the solar-wind electric field, and the observed potential drops are in remarkably good agreement with a simple analytic theory (Hill-Siscoe model). Apparently the intense magnetosphere-ionosphere currents deform the magnetic field and flow near the dayside magnetopause, reducing the reconnection rate. Mass-loading and field-aligned potential drops may also play a role. Details are being investigated using global MHD simulations. Superstorms give rise to a very different phenomenon near the equatorward edge of the nightside auroral zone, where strong electric-field regions called SubAuroral Polarization Streams (SAPS) are observed. The corresponding fast magnetospheric flows affect plasmaspheric erosion and ring-current injection. Strong magnetospherically generated electric fields penetrate to the equatorial ionosphere, causing massive uplift of the F-layer on the day side and near dusk. SAPS and equatorial penetration events affect the structure of the mid- and low-latitude ionosphere and apparently have dramatic effects on Total Electron Content observed by GPS.
DE: 2411 Electric fields (2712)
DE: 2443 Midlatitude ionosphere
DE: 2730 Magnetosphere--inner
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2760 Plasma convection
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting