HR: 09:15h
AN: SA11B-05    [Abstracts]
TI: Two Components of Ionospheric Plasma Structuring at Mid-latitudes during Large Magnetic Storms
AU: * Basu, S
EM: sbasu@bu.edu
AF: Boston University, Center for Space Physics, Boston, MA 02215 United States
AU: Basu, S
EM: basu@ppd.nrl.navy.mil
AF: AFRL (VSBXI), 29 Randolph Road, Hanscom AFB, MA 01731 United States
AU: Makela, J
EM: jmakela@ssd5.nrl.navy.mil
AF: NRL, 4555 Overlook Avenue, Washington, DC 20375 United States
AU: Sheehan, R
EM: robert.sheehan@hanscom.af.mil
AF: Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 United States
AU: MacKenzie, E
EM: eileen.mackenzie@hanscom.af.mil
AF: Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 United States
AU: Keskinen, M
EM: keskinen@ppd.nrl.navy.mil
AF: NRL, 4555 Overlook Avenue, Washington, DC 20375 United States
AU: Pallamraju, D
EM: raju@cawses.bu.edu
AF: Boston University, Center for Space Physics, Boston, MA 02215 United States
AU: Paxton, L
EM: larry.paxton@jhuapl.edu
AF: JHU/APL, Johns Hopkins Road, Laurel, MD 20723 United States
AB: Analysis of VHF amplitude scintillation and GPS phase fluctuation data in conjunction with global GPS total electron content (TEC) maps, ground-based measurements of daytime aurora and TIMED GUVI images have indicated that there are two distinct plasma processes that give rise to mid-latitude ionospheric irregularities during large magnetic storms. One is associated with auroral plasma processes and the other with storm enhanced density (SED) features which have been shown to be the ionospheric signatures of plasmaspheric tails (Foster et al., GRL, 2002). The auroral nature of one class of events is observed either during local daytime or nighttime conditions depending on the time of storm commencement and the fast rate of decrease of the SYM-H index which is generally an indicator of the rapid development of the ring current and an equatorward movement of the plasmapause. The second class of events is associated with the ionospheric density gradients seen at the edges of SEDs, which frequently occur in conjunction with large northward and westward plasma convection, and are observed primarily in the afternoon-dusk sector. Examples of both classes of events are provided from the large storms that occurred during October 29-31, 2003 and March 31, 2001. Initial results have been published on the SED associated plasma structuring by an ion temperature gradient convective instability (Keskinen et al., GRL, 2004).
DE: 2411 Electric fields (2712)
DE: 2439 Ionospheric irregularities
DE: 2471 Plasma waves and instabilities
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2788 Storms and substorms
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting