GPS Sounding of the ionosphere onboard CHAMP

Abstract

Space based GPS measurements onboard Low Earth Orbiting (LEO) satellites provide a unique possibility for exploring the ionosphere on a global scale. Both the radio occultation measurements in the limb sounding mode and the navigation measurements using a zenith viewing GPS antenna provide the Total Electron Content (TEC) along numerous ray paths that may effectively be used for reconstructing the spatial and temporal distribution of the electron density in the ionosphere and plasmasphere. Reported are results obtained from radio occultation measurements on CHAMP which have provided more than 180,000 vertical electron density profiles so far. These observations contribute for better understanding the regular behavior of the global 3D ionosphere. Furthermore, the radio occultation measurements indicate irregular and/or wavelike structures in the ionosphere which may have severe impact on the functionality of radio systems. A three-dimensional imaging of the electron density distribution near the CHAMP orbit plane between CHAMP and GPS orbit height is performed by using link related TEC data derived from dual frequency navigation measurements (zenith antenna) onboard CHAMP. This type of measurements provides a good measure of the interaction of the solar wind with the global Earth’s atmosphere, thus providing a good opportunity for studying this interaction via the magnetosphere.