Verification of CHAMP Radio-Occultation Observations in the Ionosphere Using MIDAS

The MIDAS (Multi-Instrument Data Analysis System) algorithm performs a 4dimensional mathematical inversion. It is designed to assimilate a number of different measurement techniques, thus allowing the spatial and temporal factors to be accounted for in the inversion. In this study ionospheric data have been collected together from a number of observations in Europe. The MIDAS program incorporates these data into a single 4-D inversion and produces electron concentration maps. CHAMP occultations over Europe have been identified for comparison purposes and the data have been inverted using a newly developed technique. First results indicate excellent agreement between the specification of the ionospheric electron concentration using MIDAS and that calculated from CHAMP.