New variable - Tsunami wave amplitude

[champikagallage]

Initial request

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

Amendment details

Name: Tsunami wave amplitude Definition: 1) absolute value of the difference between a particular peak or trough of the tsunami and sea level at that time, or 2) half the difference between an adjacent trough and peak and can be corrected for the change of tide between that trough and peak.

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

[PaoloLeoniIT]

If we consider the pure definition of amplitude: The amplitude of a periodic variable is a measure of its variation within a single period (such as a time or spatial period). The amplitude of a non-periodic signal refers to its magnitude relative to a reference value. There are various definitions of amplitude (see below), all of which relate to the magnitude of the differences between the variable’s extreme values. In older texts, the phase of a periodic function is sometimes referred to as the amplitude. (Knopp, Konrad; Bagemihl, Frederick (1996). Theory of Functions, Parts I and II. Dover Publications. p. 3. ISBN 978-0-486-69219-7)

Therefore, the first definition is preferable to the second one. "absolute value of the difference between a particular peak or trough of the tsunami and sea level at that time"

[champikagallage]

On behalf of ESAC-Ocean, agree with the above suggestion. Please move this to the next step.

[amilan17]

@champikagallage will you please update the amendment details in the first comment to reflect this decision?

[amilan17]

Should the path be Ocean/Currents? or Physical Properties?

[champikagallage]

I have updated the definition to reflect what Paolo suggested. The path should be Ocean/Physical Properties.

[amilan17]

@PaoloLeoniIT Can you update the branch?

[PaoloLeoniIT]

@PaoloLeoniIT Can you update the branch? Sorry @amilan17 ! How can I update the branch?

[amilan17]

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

@champikagallage please review branch

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/Meeting.2025.07.01 notes:

the team discussed the definition and noted that "at that time" sounds like a comparison of the tsunami to itself

@champikagallage the team suggests this revision:

"Absolute value of the difference between a particular peak or trough of the tsunami wave and the expected undisturbed sea level at that time."

[amilan17]

for reference:

[champikagallage]

We agree with the definition: "Absolute value of the difference between a particular peak or trough of the tsunami wave and the undisturbed sea level at that time." However, our experts do not have a strong reservation about adding "expected" either.