Fiducial Reference Measurements for Vegetation (FRM4VEG) is a European Space Agency (ESA) funded 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’. Ideally, they should:

• Have documented SI traceability.
• 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.