Accuracies of Atmospheric Profiles Obtained from GPS Occultations

Kenneth R. Hardy, George A. Hajj and E. Robert Kursinski

Abstract:	Radio occultation studies of the terrestrial atmosphere are possible through use of signals transmitted by satellites of the Global Positioning System (GPS) and received by one or more other satellites in low earth orbit (LEO). The perturbed phase of the occulted signal gives direct information on the refractivity profile in the region of occultation, from which vertical profiles of density, pressure, and temperature can be retrieved. The technique requires the use of the dual GPS frequencies in order to isolate and remove most of the ionospheric effect. Analysis of the effect of the ionosphere and methods of removing it will be presented. For the recovery of atmospheric profiles, two major issues are addressed. The first is how accurately can refractivity be retrieved for a region in which there is a large horizontal refractivity gradient; the second considers the separation of temperature and moisture in the lower troposphere. Based on model simulations, the capability of GPS to provide atmospheric profiles is assessed.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	1545 - 1556
Cite this article:	Hardy, Kenneth R., Hajj, George A., Kursinski, E. Robert, "Accuracies of Atmospheric Profiles Obtained from GPS Occultations," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 1545-1556.
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