GCOS-GOOS-WCRP Ocean Observations Panel for Climate
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Essential Ocean Variables (EOVs)

In response to the Framework for Ocean Observing, the panels of the Global Ocean Observing System will identify the Essential Ocean Variables for physics (OOPC), biogeochemistry and biology/ecosystems. For OOPC, many of these have already been established as ocean based Essential Climate Variables. However, there are requirements for physics observations beyond those just for climate, particularly in relation to coastal inundation and hazards. It is also timely to review the Ocean ECV's in terms of both their fitness for purpose, and implementation status.

OOPC has developed specification sheets for each of the Physics EOVs. (pdfs)

Temperature. Surface, Interior

Salinity. Surface, Interior

Currents. Surface, Interior

Sea Surface Height

Sea Ice

Sea State

Ocean Surface Vector Stress (new)

Sensible and Latent Heat Fluxes (proposed)

Those for Biogeochemistry can be found at www.ioccp.org/foo, and those for biology are under development.

Essential Climate Variables (ECVs)

The Global Climate Observing System identifies Essential Climate Variables, that are both currently feasible for global implementation, and are required to support the work of the Intergovernmental Panel on Climate Change (IPCC) and the UN Framework Convention on Climate Change (UNFCCC). OOPC assesses requirements for, and reviews implementation of the ocean ECVs, and also works with the Atmospheric Observations Panel for Climate (AOPC) requirements for variables at the air-sea interface. As our knowledge and capabilities develop, new variables may be added to the ECVs.

Atmosphere surface:

Air temperature




Air pressure, sea level pressure (SLP)


Surface radiation budget


Wind speed and direction


Water vapour



Ocean surface:

Sea surface temperature (SST)


Sea surface salinity (SSS)


Sea level


Sea state


Sea ice




Ocean colour (for biological activity)


Carbon dioxide partial pressure (pCO2)



Ocean subsurface:











Ocean tracers



Essential Variables 

Defining requirements for observations.

Essential Variables

Figure: Conceptual Overlap of Essential Ocean Variables in a Venn diagram. Essential Variables defined by the WMO for weather forecasting inspired the Essential Climate Variables later defined by GCOS. The concept has been adopted for Essential Biodiversity Variables on land by GEOBON. The Framework for Ocean Observing processes will define ocean observing EOVs. Overlap among these groups is shown, which argues for the need to adopt a consistent approach. (Source: Framework for Ocean Observing).





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