Modeling the Thermospheric Density Variations over Major Solar Storms using the Disturbance Storm-Time Index

There have been numerous major solar storms that have occurred over the last decade. Among them have been the Bastile Day 2000 storm, the April 2001 storm, and the Halloween storms of 2003 and 2004. Each of these storms has produced major X flares coupled with extremely large CMEs, which in turn produced major thermospheric density variations. Prior to 2008 thermospheric density models have used the geomagnetic index ap to model these density changes, with inconsistent and inaccurate results in all cases. A new empirical thermospheric density model, Jacchia-Bowman 2008 (JB2008), was developed using satellite observed density corrections and the Disturbance Storm-Time Dst index to accurately model storm time density variations. This presentation describes the modeling of the storms using this storm index, the accuracy of the modeling compared with the High Accuracy Satellite Drag Model data, and additionally uses the very accurate satellite accelerometer data from the CHAMP and GRACE satellites in the evaluation. The global densities observed by HASDM, CHAMP, and GRACE are presented for these four major storms, along with the modeled density values from the new JB2008 empirical model.