Fiducial Reference Measurements (FRM)


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The definition of the Fiducial Reference Measurement (FRM)  as provided in the preface on page xiii of the [Banks et al. 2020] is adapted from the original idea of [Donlon et al. 2013, 2014a, 2014b] for Sea Surface Temperature measurements, whereby the defining mandatory characteristics of a FRM are as follows.

The FRM must:

  • have documented traceability to SI units (via an unbroken chain of calibrations and comparisons);
  • be independent from the satellite retrieval process;
  • be accompanied by a complete estimate of uncertainty, including contributions from all FRM instruments and all data acquisition and processing steps[1];
  • follow well-defined protocols/community-wide management practices and;
  • be openly available for independent scrutiny.

[1] Here, guided by the International Vocabulary of Metrology (VIM) [BIPM et al. 2012], the original phrase has been truncated with the removal of the second part “[An uncertainty budget for all FRM ... measurements,] traceable where appropriate to the International System of Units/Système International d’unités (SI), ideally through a National Metrology Institute”. It is the measurement result that must be traceable to SI (as noted in the first mandatory characteristic), not the uncertainty estimate.


BIPM, IEC, IFCC, ILAC, ISO, IUPAC, IUPAP and OIML (JCGM), International Vocabulary of Metrology — Basic and General Concepts and Associated Terms (VIM), JCGM, 2012.

Banks, A.C.; Vendt, R.; Alikas, K.; Bialek, A.; Kuusk, J.; Lerebourg, C.; Ruddick, K.; Tilstone, G.; Vabson, V.; Donlon, C.; et al. Fiducial Reference Measurements for Satellite Ocean Colour (FRM4SOC), Remote Sens. 2020, 12, 1322, doi:10.3390/rs12081322.

Donlon, C.; Goryl, P. Fiducial Reference Measurements (FRM) for Sentinel-3. In Proceedings of the Sentinel-3 Validation Team (S3VT) Meeting, ESA/ESRIN, Frascati, Italy, 26–29 November 2013.

Donlon, C.J.; Wimmer, W.; Robinson, I.; Fisher, G.; Ferlet, M.; Nightingale, T.; Bras, B. A., Second-Generation Blackbody System for the Calibration and Verification of Seagoing Infrared Radiometers. J. Atmospheric Ocean. Technol. 2014, 31, 1104–1127, doi:10.1175/JTECH-D-13-00151.1.

Donlon, C.J.; Casal, T., Sentinel-3 Scientific Validation Team Implementation Plan, EOP-SM/2641/CD-cd, ESA, EUMETSAT, 2014

Zibordi, G. and Donlon, C.J.; Chapters  3 and 5, vol. 47, Zibordi, G. and Donlon, C.J., and Parr, A. C. Eds. Academic Press, 2014.