Hélène Roinard (Collecte Localisation Satellite, France); Nicolas Picot (CNES, France); Thierry Guinle (CNES, France)

On August 10 1992, the TOPEX/POSEIDON satellite was successfully launched into orbit by an Ariane 42P rocket from the French Guiana launch site. For the next 13½ years, the two radar altimeters on board the platform, the NASA Altimeter (ALT) and SSALT (or POSEIDON-1), successfully collected valuable oceanographic data. Since both altimeters operated at the same frequency and used the same antenna, a sharing plan of the antenna was established which allowed operation of the ALT 90% of the time with the remaining 10% devoted to POSEIDON-1 operation.

We propose in this paper to report on the POSEIDON-1 reprocessing activity that was performed by CNES/CLS teams. It included the reprocessing of all internal calibration sequences, the retracking of the waveforms and the update of the instrumental corrections. POSEIDON-1 proved to have an excellent instrumental stability (drift internal path delay below 0.6 mm/yr) making it valuable to contribute to the TOPEX‐A drift on going analysis. In addition to being useful for the Global Mean Sea Level determination, this reprocessing also offered the possibility to secure the POSEIDON-1 data set and to enrich the long term altimetry records with homogenized data set.