CoAuthors

Craig Donlon (European Space Agency, The Netherlands); Pierre Femenias (European Space Agency, Italy); Constantin Mavrocordatos (European Space Agency, The Netherlands); Demitris Galanakis (Space Geomatica P.C., Greece); Tommaso Parrinello (European Space Agency, Italy); Francois Boy (CNES, France); Ilias Tziavos (Aristotle University of Thessaloniki, Greece); George Vergos (Aristotle University of Thessaloniki, Greece); Xenofon Frantzis (Technical University of Crete, Greece); Achilles Tripolitsiotis (Space Geomatica P.C., Greece)

This work describes the absolute and relative bias estimation of satellite altimeters using different and independent techniques at the Permanent Facility for Altimeter Calibration in west Crete, Greece. Both absolute direct (i.e., transponder) but also absolute indirect (i.e., sea-surface) calibrations are implemented for Sentinel-3, and Jason-3 satellites. Independent Cal/Val techniques are compared to each other, attaining fiducial reference measurement standards with well documented procedures, for the same satellite orbit, and maximizing the reliability for the Jason-3 and Sentinel-3 Cal/Val results.

As Jason-3 moves from north over the transponder, it continues on its south-east orbit and passes over an open sea area, west of the Gavdos Cal/Val facility. The opposite happens for the Sentinel-3A. It takes off its ascending path from the south with sea-surface calibration, while it reaches the CDN1 transponder Cal/Val site along its ascending norther pass. The Jason-3 descending Pass No.18 and Sentinel-3A ascending pass No.14 are both calibrated at the transponder CDN1 Cal/Val site.

Sea-surface calibration results for the ascending Jason-3 Pass No.109 and the descending No.18, as well as Sentinel-3 ascending No.14 but also descending No.335 passes will be presented. Transponder Cal/Val results will also be presented for both satellites in the LRM and SAR modes. CryoSat-2 is also calibrated at the CDN1 Cal/Val site. Finally, relative calibration against other altimetry missions at crossover locations will be also shown.