IONOSPHERE TOMOGRAPHY WITH DATA FROM SATELLITE RECEPTION OF GLOBAL NAVIGATION SATELLITE SYSTEM SIGNALS AND GROUND RECEPTION OF NAVY NAVIGATION SATELLITE SYSTEM SIGNALS

GPS/MET, a multichannel Global Positioning System (GPS) receiver onboa rd the small research satellite MicroLab 1, is the first example of a research tool of great importance for ionospheric research. In the nea r future, other satellites with GPS/GLONASS (Global Navigation Satelli te System (also GNSS)) receivers will be launched. Their main purpose is lower atmosphere research, but because of the necessity to correct for plasma influences, ''ionospheric'' data will be available as a sid e product. The occultation of GNSS signals offers the possibility to g ain very good quality height profiles of electron density by means of classical inversion techniques. The profiles are averaged horizontally . This paper concentrates on the possibility to complement inversion r esults with electron content data gained on the ground using beacon si gnals of low orbiting satellites (e.g., the U.S. Navy Navigation Satel lite System (NNSS)). The data combination offers several possibilities for ionospheric tomography. Several GNSS scanning satellite scenarios are assessed, and their ionospheric imaging/tomography merits are dis cussed. An example result for the inversion of GPS/MET data, is shown. The results of simulations with model ionosphere data are used to dem onstrate tomographic reconstruction techniques based on the combinatio n of ''space'' and ''ground'' electron content. The simulation results have direct applicability to observed data.