Comparison of electron density profiles from CHAMP data with NeQuick model

Vertical electron density profiles (EDP) derived from ionospheric radio occultation (IRO) measurements onboard the German CHAMP satellite are calculated by the Institute of Communications and Navigation of DLR on a regular basis since 11 April 2001. In order to validate the ionospheric radio occultation data obtained from this satellite. any systematic comparison with independent measurements but also with results from ionospheric models should help to get a better feeling about the quality of the data. On the other hand, if the IRO data quality is sufficient, the data may contribute to evaluate the accuracy of the ionospheric models. In this study we compare CHAMP EDP data derived in 2002/03 with the NeQuick model, which is one of the three electron density models developed at the Abdus Salam ICTP in Trieste (Italy) and the Institute for Meteorology and Geophysics in Graz (Austria). We discuss results of this comparison, showing changes in bias and deviation with latitude and local time. The best agreement between both types of data was found above a height of 300 km.