Spaceborne GPS remote sensing for atmospheric research

On April 3, 1995, a small radio receiver was launched into a 750 km low- earth orbit and 70 degree inclination. As this receiver orbits, occultations occur when the radio link between any one of the 24 GPS transmitters and the low-earth orbiting (LEO) receiver progressively descends or ascends through the earth's atmosphere. With the current constellation of GPS transmitters, approximately 500 such occultations occur in each 24-hour period per LEO receiver.

Several hundred occultations have been analyzed to date, where some type of confirmational data has been available (i.e., radiosonde, satellite, numerical analysis gridded data). In this paper, we present a brief outline of the method followed by a few typical temperature soundings that have been obtained.