Longitudinal Hemispheric Differences During Geomagnetic Storm Times Examined with GITM

Work by Immel and Mannucci [2013] has indicated that geomagnetic storms cause larger effects on the ionospheric TEC (Total Electron Count) in the American sector than anywhere else on the planet, suggesting that there is a longitude dependent (UT) effect which is important for correctly understanding the impact, structure and timing of geomagnetic storms. Using Global Ionosphere-Thermosphere Model (GITM) [Ridley et al., 2006] coupled with realistic transport, we examine the underlying mechanisms of the longitude-dependent storm enhancements. We accomplish this by using a case study storm observed on 5 August 2011 and then conducting model experiments with GITM by shifting the storm onset time over the course of 24 hours. TEC measurements, the Dst index, and IMF are used in conjunction with model output.