The Whole Atmosphere Model Neutral Density Data Assimilation during the November 2003 Super Storm

The Whole Atmosphere Model (WAM) is used to simulate the thermospheric neutral density in the Iterative Driver Estimation and Assimilation (IDEA) data assimilation scheme during the November 2003 super storm. Two data sources were utilized and examined to enhance the neutral density specification. The first was the accelerometer estimates of neutral density aboard the Challenging Mini-Satellite Payload (CHAMP) satellite, and the second one was the neutral density retrieved by the Global Ultraviolet Imager (GUVI) airglow measurements aboard the Thermosphere Ionosphere Mesosphere Energy and Dynamics (TIMED) satellite. Results show that WAM effectively captured the CHAMP neutral density, with bias at 0.98, RMSe at 5.7%, STD at 5.3%, and followed the time dependence at the CHAMP satellite altitude throughout the storm period. To explore alternative data sources in the IDEA system, TIMED-GUVI neutral density was further utilized to cross-compare with WAM when CHAMP data was used in IDEA. In general, GUVI exhibits closest agreement, bias of 1, RMSe of 7%, and STD of 7%, with WAM at the altitudes ranging from 280-310 km, which suggests the GUVI neutral density at 300 km could equally be used to improve the forecasting capability of the WAM neutral density in the IDEA scheme. This study demonstrates the utility of the IDEA data assimilation system and that of physical models with data assimilation can contribute to neutral density specification for enhanced orbit determination and prediction of the low Earth orbit satellites