1ST ASSESSMENT OF GPS-BASED REDUCED DYNAMIC ORBIT DETERMINATION ON TOPEX POSEIDON

The reduced dynamic GPS tracking technique has been applied for the fi rst time as part of the GPS experiment on TOPEX/Poseidon. This techniq ue employs local geometric position corrections to reduce orbit errors caused by the mis-modeling of satellite forces. Results for a 29-day interval in early 1993 are evaluated through postfit residuals and for mal errors, comparison with GPS and laser/DORIS dynamic solutions, com parisons on 6-hr overlaps of adjacent 30-hr data arcs, altimetry closu re and crossover analysis. Reduced dynamic orbits yield slightly bette r crossover agreement than other techniques and appear to be accurate in altitude to about 3 cm RMS.