CoAuthors

Craig Donlon (ESTEC/European Space Agency, The Netherlands); Constantine Mavrocordatos (ESTEC/European Space Agency, The Netherlands); Pierre Féménias (ESRIN/European Space Agency, Italy); Demitris Galanakis (Space Geomatica P.C., Greece); Ilias Tziavos (Aristotle University of Thessaloniki, Greece); Francois Boy (Centre National d'études Spatiales (CNES), France); George Vergos (Aristotle University of Thessaloniki, Greece); Ole Andersen (Danish Space Center, Denmark); Xenofon Frantzis (Tecnical University of Crete, Greece); Mingsen Lin (National Satellite Ocean Application Service, China); Achilles Tripolitsiotis (Space Geomatica P.C., Greece)

This work presents the updated results for the calibration & validation of several altimeter satellites (Jason-2, Jason-3, Sentinel-3, CryoSat-2, HY-2, SARAL/AltiKa) determined at the permanent facility for altimetry calibration, west Crete, Greece. These absolute Cal/Val results are obtained using sea-surface and transponder techniques followed by uncertainty budgets at metrology standards. This new concept of Fiducial Reference Measurement (FRM) for Altimetry is recommended by ESA to start producing Earth observation results for the future in terms of well-characterized SI units, so they are reliable, comparable world-wide and also linked to other areas of science and technology.
The latest Cal/Val absolute bias results are given at first for the Jason-2 & Jason-3 based upon the descending Pass No.18 but also on the ascending No.109, with GDR-D data at sea and on land with the transponder at the CDN1 Cal/Val site. Biases are also provided for the Sentinel-3A (baseline-2) with the ascending orbit No.14 setting out with the transponder in the mountains of Crete and continuing on the same orbit with the sea-surface infrastructure in the south of Gavdos island. Altimeter results are also produced for Sentinel-3A based on descending pass No. 335 passing over Gavdos. Using the CRS1 Cal/Val site in west Crete, results for the bias of the Chinese HY-2 satellite altimeter bias is also presented using S-GDR data (T) for its descending Pass No.280 (Cycles 1-101). Relative biases are also presented at crossover locations for several altimeters in the vicinity of the permanent facility for altimeter calibration. Future plans for the upscaling of this infrastructure and for improving the derived results will also be presented.