Within this FRM4ALT project, to derive the instrument measurement uncertainty for altimetry calibration, the following tasks will be implemented at the Permanent Altimeter Calibration Facility (PFAC), located on the island of Gavdos and mainland West Crete, Greece, towards absolute direct (sea surface & transponder) and indirect calibration (cross-over at sea and on land) of altimeters:

• Modernisation of the PFAC infrastructure and field instrumentation for attaining the utmost quality for satellite calibration values;
• Periodic instrument characterization and calibration that will provide and update instrument's measurement coefficients. This instrument characterization/calibration program will be established taking into account the need for continuous PACF operation, in SI-traceable standards;
• Establishment of procedures for relative validation of instrument's performance under the same real-life conditions. For example, the performance of different types of tide gauges (i.e., radar, acoustic, pressure) installed at the same location will be monitored, evaluated and compared to conclude on reliable and robust measurement for satellite altimeter calibration;
• Establishment of documentation to report critical instrument parameters;
• Establishment of a standardised procedure for automated and in-situ data retrieval and archival.