Improving the Extraction Ability of Ionospheric Upper Transition Height Variations From C/NOFS measurements

Understanding the temporal and spatial variation of the upper transition height (UTH) is important for ionosphere modeling and ionosphere-plasmasphere coupling physics. In this study, we proposed an approach that combine the topside density profiles from Formosat-3/COSMIC (F3/C) Radio Occultation (RO) measurements with ion composition measurements from C/NOFS satellites to recalculate ionospheric UTH. The reliability of proposed approach was validated using observations from the ISR located in Jicamarca. The latitudinal, local time and seasonal variations of UTH from re-calculation, directly measurement and International Reference Ionosphere (IRI) model are investigated and compared. The results show that the UTH increases significantly with the solar activity condition. During low solar activity conditions, is in good agreement with the observational results is in good agreement with the observational results except for the winter hemisphere. During moderate and high solar activity conditions, the IRI model underestimates the UTH by about 10% and 14.5, respectively.