Craig Donlon (ESTEC/ESA, The Netherlands); Constantine Mavrocordatos (ESTEC/ESA, Netherlands); Pierre Féménias (ESRIN/ESA, Italy); Tommaso Parrinello (ESRIN/ESA, Italy); Nicolas Picot (CNES, France); Jean-Damien Desjonqueres (CNES, France); Ole Andersen (DTU Space, Denmark)

To establish a continuous, homogeneous and reliable monitoring of the ocean and its changes, altimetry observations have to be free of errors and biases, uninterrupted, but also tied from one mission to the next in an objective and absolute sense. Altimetry system’s responses have to be, thus, continuously monitored and controlled for their quality, biases, errors, drifts, although relations among different missions have to be established on a common and reliable earth-centered reference system, maintained over a long period of time.

The objective of this presentation is to set the ground for Fiducial Reference Measurements for Satellite Altimetry in Gavdos and West Crete, Greece to "establish and demonstrate SI-traceability of altimetry measurements and their use for satellite-derived altimeter calibration and validation".

The concept of Fiducial Reference Measurements has been defined by the European Space Agency as: "The suite of independent ground measurements that provide the maximum Return-On-Investment for a satellite mission by delivering, to users, the required confidence in data products, in the form of independent validation results and satellite measurement uncertainty estimation, over the entire end-to-end duration of a satellite mission."

Results from this fiducial reference site will be based on historic Cal/Val site records, and would be the yardstick for building up capacity for monitoring the climate change records. This ground facility will be capable of defining and assessing any satellite altimeter measurements to known, controlled and absolute reference heights, and signals with different techniques, processes and instrumentation.