HR: 0800h
AN: SA21A-0269    [Abstracts]
TI: The Longitudinal Dependence of the Mid-Latitude ionospheric Effect of Large Geomagnetic Storms
AU: * David, M
EM: michael@sim2.cass.usu.edu
AF: Center for Atmospheric and Space Sciences, Utah State University 4405 Old Main Hill, Logan, UT 84322-4405 United States
AU: Sojka, J J
EM: fasojka@sojka.cass.usu.edu
AF: Center for Atmospheric and Space Sciences, Utah State University 4405 Old Main Hill, Logan, UT 84322-4405 United States
AU: Schunk, R W
EM: schunk@cc.usu.edu
AF: Center for Atmospheric and Space Sciences, Utah State University 4405 Old Main Hill, Logan, UT 84322-4405 United States
AB: In recent years much attention has been given to the effect of large geomagnetic storms over the region of the USA. Enhancements of TEC by a factor of two or more have been reported, and, of very special interest from the GPS point of view, very steep ionospheric density gradients have been reported in the American sector. A survey of recent literature on this subject leaves one to wonder whether these storm effects are confined to the longitudes of the North American continent, or whether such effects might be present around the globe. We address this question with both a modeling approach and a systematic analysis of ionosonde data from the last 20 years. In our analysis of the observations we look for the presence or absence of four specific characteristics: a dusk effect, a positive storm phase, a negative storm phase, and a steep density gradient. We have previously reported on our success in modeling the TEC enhancements and high density gradients in the American sector by introducing a penetrating electric field that induces an upward vertical drift in the dayside mid-latitude ionosphere. Here we employ the same modeling approach at other longitudes, and compare the results with ionosonde observations obtained from the SPIDR data base for stations in the magnetic latitude range of 40-50 deg.
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2443 Midlatitude ionosphere
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005