Fifteen years of Cal/Val service to reference altimetry missions: calibration of satellite altimetry at the permanent facilities in Gavdos and Crete, GreeceFifteen years of Cal/Val service to reference altimetry missions: calibration of satellite altimetry at the permanent facilities in Gavdos and Crete, Greece Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2019-06-032018enSatellite altimetry provides exceptional means for absolute and undisputable monitoring of changes in sea level and inland waters (rivers and lakes), over regional to global scales, with accuracy and with respect to the center of mass of the Earth. Altimetry system's responses have to be continuously monitored for their quality, biases, errors, drifts, etc. with calibration. Absolute calibration of altimeters is achieved by external and independent to satellite facilities on the ground. This is the mainstay for a continuous, homogenous, and reliable monitoring of the earth and its oceans. This paper describes the development of the Permanent Facility for Altimetry Calibration in Gavdos/Crete, Greece, as of 2001 along with its infrastructure and instrumentation. Calibration results are presented for the reference missions of Jason-1, Jason-2, and Jason-3. Then, this work continues with the determination of relative calibrations with respect to reference missions for Sentinel-3A, HY-2A, and SARAL/AltiKa. Calibration results are also given for Jason-2 and Jason-3 altimeters using the transponder at the CDN1 Cal/Val site on the mountains of Crete, with simultaneous comparisons against sea-surface calibration and during their tandem mission. Finally, the paper presents procedures for estimating uncertainties for altimeter calibration to meet the Fiducial Reference Measurement standards.http://creativecommons.org/licenses/by/4.0/Remote Sensing1010Mertikas_et_al_Remote Sens._10(10)_2018.pdfChania [Greece]Library of TUC2019-05-31application/pdf17.5 MBfree Mertikas Stylianos Μερτικας Στυλιανος Donlon Craig Féménias Pierre Mavrocordatos Constantin Galanakis Dimitrios Γαλανακης Δημητριος Tripolitsiotis Achilleas Τριπολιτσιωτης Αχιλλεας Frantzis Xenofon Φραντζης Ξενοφων Tziavos, Ilias N Vergos George Guinle Thierry MDPI Altimetry Calibration Fiducial reference measurements Jason Sea surface Transponder