TIME-IGGCAS model validation: Comparisons with empirical models and observations

The TIME-IGGCAS (Theoretical Ionospheric Model of the Earth in Institute of Geology and Geophysics, Chinese Academy of Sciences) has been developed recently on the basis of previous works. To test its validity, we have made comparisons of model results with other typical empirical ionospheric models (IRI, NeQuick-ITUR, and TItheridge temperature models) and multi-observations (GPS, Ionosondes, Topex, DMSP, FORMOSAT, and CHAMP) in this paper. Several conclusions are obtained from our comparisons. The modeled electron density and electron and ion temperatures are quantitatively in good agreement with those of empirical models and observations. TIME-IGGCAS can model the electron density variations versus several factors such as local time, latitude, and season very well and can reproduce most anomalistic features of ionosphere including equatorial anomaly, winter anomaly, and semiannual anomaly. These results imply a good base for the development of ionospheric data assimilation model in the future. TIME-IGGCAS underestimates electron temperature and overestimates ion temperature in comparison with either empirical models or observations. The model results have relatively large deviations near sunrise time and sunset time and at the low altitudes. These results give us a reference to improve the model and enhance its performance in the future. Supported by the KIP Pilot Project of CAS (Grant No. kzcx2-yw-123), National Natural Science Foundation of China (Grant Nos. 40636032 and 40725014), and National Key Basic Research Project of China (Grant No. 2006CB806306)