UNESCO IOC GOOS
Essential Ocean Variables - Global Ocean Observing System
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To be able to deliver ocean forecasts and early warnings, climate projections and assessments and protect ocean health and its benefits, it is vital to measure Essential Ocean Variables (EOVs).
GOOS EOVs are defined as the minimum set of ocean variables that are needed to assess ocean state and variability for important global ocean phenomena (see
GOOS phenomena list
), and to provide essential data for applications that support societal benefit.
They are derived from sustained individual measurements, or combinations of measurements, that can be undertaken at global scale and in a cost-effective manner.
Because EOVs are perennial, they allow the observing system to change and develop around them as technology and capability evolve.
Our GOOS Expert Panels identify the EOVs based on:
Impact
: the variable addresses climate, operational ocean services and ocean health and also contributes to understanding from a scientific perspective or application from a service perspective.
Feasibility
: it is technically, politically and economically feasible to observe or derive the variable on a global scale using proven, scientifically understood methods.
When EOVs are identified, our Expert Panels create and share a series of recommendations. These include what measurements are made, observing options and data management guidelines.
The majority of EOVs are also
Essential Climate Variables
(ECVs) defined by the
Global Climate Observing System
. ECVs cover atmospheric, oceanic, and terrestrial domains. A number of GOOS ocean observing networks measure atmospheric and oceanic ECVs.
Related links:
EOV Adoption process
EOV Publication in Frontiers in Marine Science
GOOS phenomena list
Graphical abstract of the recent publication “GOOS Essential Ocean Variables: the backbone of a sustained and evolving global ocean observing system” in Frontiers in Marine Science (Martín Miguez & Heslop et al. 2026)
EOV specification sheets
Click on the items in the list below to download each EOV specification sheet for details on requirements, tracing through from applications to phenomena to observing, and for authors for queries. The columns indicate the GOOS Expert Panel that has lead responsibility for each EOV.
A guide on how to use the EOV specification sheets can be downloaded
here
Note: The EOV specification sheets are currently under revision and will be updated soon.
Physics
Biochemistry
Biology and Ecosystems
Sea state
Ocean surface stress
Sea ice
Sea surface height
Sea surface temperature
Subsurface temperature
Surface currents
Subsurface currents
Sea surface salinity
Subsurface salinity
Ocean surface heat flux
Ocean bottom pressure
Turbulent diapycnal fluxes (*pilot)
Oxygen
Nutrients
Inorganic carbon
Transient tracers
Particulate matter
Nitrous oxide
Stable carbon isotopes
Dissolved organic carbon
Phytoplankton biomass and diversity
Zooplankton biomass and diversity
Fish abundance and distribution
Sea turtles abundance and distribution
Seabirds abundance and distribution
Marine mammal abundance and distribution
Coral cover and composition
Seagrass cover and composition
Macroalgal canopy cover and composition
Mangrove cover and composition
Microbe biomass and diversity (*pilot)
Benthic invertebrate abundance and distribution (*pilot)
Cross-disciplinary (including human impact)
Ocean sound
Ocean colour
Marine debris (*pilot)
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Who makes up GOOS
Find out about the Global Ocean Observing System community.
Click here
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