Context
The oceanographic community deals with a wide variety of different quantities and uses very different techniques to measure EOVs.
Oceanographic research institutions are well organised in Europe and internationally — and cover most EOVs. However, an institutional infrastructure to cover the metrological needs is not established within those structures. It is therefore essential that communities such as NMIs/DIs and oceanographic scientists combine efforts to establish a metrological infrastructure to address the metrological requirements for EOVs.
The table summarises the actions needed to ensure the longterm comparability of ocean observation data and the metrological references necessary to cover the GCOS/GOOS quality requirements for the EOVs.
Measurement challenges
- Defining adequate traceability for measurands and fit-for-purpose high order and working standards to ensure unbroken SI-traceable calibration chains, preferably traceable to the SI. Currently, some ocean ECVs and EOVs are not defined in terms of SI units (e.g. pH, salinity, making it difficult to ensure their longterm comparability.
- Certified reference materials (CRMs) are tools to ensure the metrological traceability of results via the calibration of instruments, or to validate analytical measurement methods. Few reference materials exist for some ocean ECVs and EOVs (e.g., inorganic carbon variables, pCO2, TA, pH) and most of them are not certified by NMIs/DIs. Moreover, CRMs are often not used because of a lack of resources.
- On-board calibration for underwater instruments mounted on research vessels able to continuously measure oceanographic parameters such as temperature, salinity, pressure, sound speed, and bathymetry — to ensure traceability and accuracy of measurements over instrument lifetimes and account for environmental conditions and operation in dynamic mode.
Key stakeholders
- IOC-UNESCO, GOOS, GOA-ON, MINKE Starting community, IAPSO, JPI Oceans, ICOS, IOCCP, OBPS