HR: 1340h
AN: SM23A-0493    [Abstracts]
TI: The Influence of Geomagnetic Storms on the D-Region at Mid-Latitudes
AU: * Peter, W B
EM: wpeter@stanford.edu
AF: STARLab, Stanford University, 350 Serra Mall Packard Building, Room 351, Stanford, CA 94305
AU: Inan, U S
EM: inan@nova.stanford.edu
AF: STARLab, Stanford University, 350 Serra Mall Packard Building, Room 351, Stanford, CA 94305
AB: Subionospherically propagating Very Low Frequency (VLF) signals have long been used to detect perturbations of the upper atmosphere. In this paper, we examine the effects of several geomagnetic storms, including the Halloween storm (late October of 2003), on the D-region of the ionosphere using several VLF/LF signal paths in both the northern and southern hemispheres. The amplitudes of the received VLF signals exhibit rapid fluctuations following increased geomagnetic activity, with the fluctuations persisting several days after the advent of the geomagnetic storm. We examine the frequency content of these rapid fluctuations, as well as the location and timing of the disturbances, using multiple VLF/LF signal paths. The occurrence rate of lightning-induced electron precipitation (LEP) events, as recorded on several VLF/LF signals, was seen to be highly variable with geomagnetic activity. Comparison of LEP event occurrence rates with measurements of energetic electron flux levels from the NOAA-POES satellite supports the notion that this variability in the number of LEP events detected is largely due to increases in the energetic electron population in the slot region with the advent of geomagnetic activity. Finally, the modulation of the amplitude of received VLF/LF signals at ULF frequencies, possibly due to the Field Line Resonance (FLR) effect, is explored.
DE: 2435 Ionospheric disturbances
DE: 2443 Midlatitude ionosphere
DE: 2483 Wave/particle interactions
DE: 2716 Energetic particles, precipitating
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting