Comparison of the CHAMP radio occultation data with the Canadian advanced digital ionosonde in the Polar Regions

In this paper we present the results of the comparison of the retrieved electron density profiles of the Ionospheric Radio Occultation (IRO) experiment on board CHAMP (CHAllenging Minisatellite Payload), with the ground ionosonde profiles for the Polar Regions. IRO retrieved electron density profiles from CHAMP are compared with Canadian Advanced Digital Ionosonde (CADI) measurements at two vertical sounding stations well within the Polar Cap, Eureka (geog. 80°13′ N; 86°11′ W) and Resolute Bay (geog. 74°41′ N; 94°54′ W). We compared the ionospheric parameters such as the peak electron density of the F-layer (NmF₂) and the peak height of the F-layer (h_mF₂) for a 3-year period, 2004–2006. CHAMP derived NmF₂ shows reasonable agreement with the ionosonde retrieved NmF₂ for both the stations (0.76 and 0.71 correlation coefficient, for Eureka and Resolute Bay, respectively) whereas the h_mF₂ agreement is not that acceptable (0.25 and 0.37 correlation coefficient, respectively). The h_mF₂ from vertical sounding showed less spread than the CHAMP h_mF₂.