Validation of Radio Occultation Techniques Using Ground Digital Ionosonde Measurements in the Polar Regions

Radio Occultation using Global Positioning System (GPS) satellites and Low Earth Orbit (LEO) satellites are widely used for ionospheric studies and are a powerful tool for monitoring the Earths ionosphere. In this dissertation I present the results of the validation of the retrieved electron density profiles of the Ionospheric Radio Occultation (IRO) measurements on board CHAMP (CHAllenging Minisatellite Payload), using 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). I compared the key ionospheric parameters such as the critical frequency of the F layer (foF2) and the maximum height of the F layer (hmF 2) for a three-year period, 2004 to 2006. CHAMP derived foF2 agrees well with the ionosonde derived foF2 for both the stations whereas the hmF2 agreement is not that acceptable. The hmF 2 from vertical sounding showed less spread than the CHAMP hmF2. Reasons for this disagreement are investigated.