Fiducial Reference Measurements

The Sentinel-3 Validation Team (S3VT) has established the concept of Fiducial Reference Measurements (FRM) as:

“The suite of independent ground measurements that provide the maximum Return On Investment (ROI) 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.”

The defining mandatory characteristics for FRM are:

• FRM measurements have documented SI traceability (eg. via round-robin characterisation and regular (pre-and post deployment) calibration of instruments) using metrology standards (eg. [RD-4], [RD-8]).
• FRM measurements are independent from the satellite geophysical retrieval process.
• An uncertainty budget for all FRM instruments and derived measurements is available and maintained (eg. [RD-5]).
• FRM measurement protocols, procedures and community-wide management practices (measurement, processing, archive, documents etc.) are defined, published openly and adhered to by FRM instrument deployments.
• FRM are accessible to other researchers allowing independent verification of processing systems.

FRM are required to determine the on-orbit uncertainty characteristics of satellite geophysical measurements via independent validation activities.