Sentinel-2.  Image: ESA/ATG medialab.

Fiducial Reference Measurements for Vegetation (FRM4VEG) is a European Space Agency (ESA) managed project focused on establishing the protocols required for traceable in-situ measurements of vegetation-related parameters, to support the validation of Copernicus products from Sentinel-2, -3, and PROBA-V.

FRMs are ‘the suite of independent ground measurements that provide the maximum return on investment 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’.  FRMs should:

  • Have documented SI traceability (or conform to appropriate international community standards).
  • Be independent from the satellite geophysical retrieval process.
  • Be accompanied by an uncertainty budget for all instruments and derived measurements.
  • Adhere to community-agreed, published and openly-available measurement protocols/ procedures and management practices.
  • Be accessible to other researchers allowing independent verification of processing systems.

The project aims to develop techniques for applying, insofar as is possible, the FRM concept to in-situ measurements of three vegetation-related parameters.  These are surface reflectance, the fraction of absorbed photosynthetically active radiation (FAPAR) and canopy chlorophyll content.

Phase 1 of the FRM4VEG project took place between 2018 and 2019, involving the definition of protocols, procedures and validation methodologies, which were then applied over two field campaigns.

Phase 2 will involve the consolidation of the protocols, procedures and validation methodologies developed in Phase 1, additional field campaigns, a round robin exercise, and detailed consideration of permanent instrumentation for deployment over validation supersites.