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.