Fiducial reference measurements for satellite altimetry calibration: The constituents

Abstract

This work defines the concept of Fiducial Reference Measurements (FRM) for altimetry calibration. It has emerged out of the requirement for reliable, consistent, standardized and undisputable Earth observation records. FRM observations are to become comparable worldwide, insensitive to instrument, satellite, setting, location and measurement conditions among others. At first, the paper singles out the various contributing error sources to the calibration error budget in altimetry. Secondly, it evaluates measurement uncertainty as it originates from each constituent in the error propagation chain. Third, it sets the foundation for connecting measurement uncertainty so that it could be traceable to international metrology standards (speed of light, atomic time, for example). Finally, this paper presents procedures, protocols and best practices for arriving at FRM standards in sea-surface but also in transponder calibration. This analysis is based on experience gained over the last 15 years of operation of the permanent facility for altimetry calibration in west Crete, Greece.