Time Reference, Calibration and Time Transfer Techniques for Satellite Altimetry

Synchronisation of a remote clock to a time reference can be challenging. Within the timing community these challenges have been addressed, and robust time transfer and calibration techniques have been developed offering differing levels of synchronization accuracy to the international time reference UTC, Coordinated Universal Time. These techniques can be applied to timing equipment at ground-based Cal/Val (Calibration/Validation) sites in Western Crete and elsewhere to achieve FRM (fiducial reference measurements) for altimetry, satisfying their requirement for SI (International System of units) traceability. Continuous monitoring of the remote sites is required to maintain traceability to the reference time, and a holdover clock may also be needed. This paper discusses how UTC or TAI (International Atomic Time) could be used as a time reference for timestamped measurements taken at Cal/Val sites, improving measurement uncertainty and linking fiducial reference measurements for satellite altimetry back to the SI unit of time: the second.