Observation and simulation of direct and reflected GPS signals in radio occultation experiments

GPS/MET radio occultation observations are analyzed with the radio holographic method. Using the Multiple Signal Classification algorithm power spectra of 2038 radio holograms observed Between 2 February and 16 February 1997 are calculated. In about 28% of the analyzed L1-band spectra secondary frequency components are found at power levels of about 10-20 dB below the main component. These secondary components are interpreted as signatures of GPS signals reflected at Earth's surface. Results from geometrical ray tracing simulations support our interpretation.