Table 1-01-03 New variable - Sea level

[champikagallage]

Initial request

We are requesting to add the new variable Sea level which is part of ESAC-Ocean requirement in the RRR process.

Amendment details

Name: Sea level Definition: New variable - The Height of the Ocean Surface relative to a reference geoid or an agreed regional datum Note: Sea level includes all components of change and is broader than Ocean dynamic topography (ODT)

Requestor(s)

ESAC-Ocean

Stakeholder(s)

GOOS, OCG, OceanOPS

Applications or Systems

• [X] OSCAR/Surface
• [X] OSCAR/requirements
• [ ] Radar/DB
• [X] OceanOPS
• [ ] WHOS
• [ ] WDQMS
• [ ] GBON Compliance Monitor
• [ ] Other

Expected impact of change

None

Collaborators

No response

References

No response

Comments

No response

Publication(s)

Manual on Codes (WMO-No. 306), Volume I.3, WMO Codes Registry - WMDR

Validation

No response

[amilan17]

would the path be Ocean/Physical Properties? And how does this differ from Sea Surface Height?

[amilan17]

@champikagallage were you going to ask about the difference between this request for "sea level" and SSH?

[champikagallage]

I am in the process of consulting the ESAC-Ocean PoCs to get their view on SSH and Sea Level. I will update this as soon as I hear back from them.

Here is some information we gathered so far. But we have not come to a conclusion yet.

Further, SSH is measured with altimetry in the open ocean, and for forecasting, you use data from altimeters. But at the coast, we have tide gauges indicating how the sea level changes with respect to their local reference. We do not use altimeters to understand the tide, nor for harbour operations. With altimeters one cannot understand whether there is going to be an intrusion of salty water in freshwater reservoirs, because that depends on the local subsidence too.

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/Meeting.2025.06.12 notes:

Champika is still working with colleagues to get clarity; Washington noted that hydrology has a different definition/perspective for water level height

[champikagallage]

After consulting the experts, the decision is to hold this request for the moment as SSH can be used in some applications. There are discussions ongoing in the OOPC (Ocean Observations Physics and Climate) Panel on Sea Level variable. We will come back to this group once there is a clear decision on this variable from OOPC: therefore, I request to hold this item until further notice.