USU GAIM: Validation of the Ionospheric Forecasting Model (IFM) Using the TOPEX TEC Measurements

As a part of the validation program in the USU GAIM project, a newly improved Ionospheric Forecasting Model (IFM) was systematically validated by using a large database of the TOPEX TEC measurements. The TOPEX data used for the validation is for the period from August 1992 to March 2003 and the total number of 18-second averaged data is close to 11 million. This model validation work covers a wide range of seasonal (winter, summer, equinox) and solar (low, median, and high F10.7) conditions as well as all UT variations. The validation results indicate that the features of the spatial distrubution of the IFM TEC are systematically consistent to those of the TOPEX TEC. The differences between the IFM TEC and the TOPEX are within 20% for almost all locations and conditions. In many conditions, the differences are even below 10%. This validation work further proves the validity of the IFM for the ionospheric assimilation in the USU GAIM project.