The Air Force Geophysics Laboratory (AFGL) computer program SARRA (Short Arc Reduction of Radar Altimetry) has been used for geoid determination with altimetric observations from the GEOS-3 satellite. A unique feature of SARRA is the simultaneous recovery of the orbit parameters and the surface coefficients as defined by the kernel function analysis. Orbits good to approximately 20 meters are adequate for precise geoid determinations by virtue of the orbital adjustment in the reductions. Alimetric data over adjacent areas of the Indian and South Pacific Oceans and a portion of the North Atlantic have been processed with the SARRA program. Preliminary results indicate that highly accurate reference orbits are not a stringent requirement for the AFGL SARRA reductions. The recovered geoid in the GEOS-3 calibration area shows good agreement with gravimetric geoids in that area. |