Standard names: *Friction Velocity in Sea Water*

[abiardeau]

Hello,
I am Aurore BIARDEAU from Mercator Ocean international, working for Copernicus Marine service.
Date : 13-05-2024

We are in the process of implementing a new variable in the Copernicus Marine service and we would be happy to have your feedback on our proposal :

standard_name : eastward_friction_velocity_in_sea_water (same for northward)
(Inspired by existing standard_name eastward_friction_velocity_in_air)

unit : m s-1

I can provide more information from my expert colleagues if needed,
Kind regards,
Aurore

[github-actions]

Thank you for your proposal. These terms will be added to the cfeditor (http://cfeditor.ceda.ac.uk/proposals/1) shortly. Your proposal will then be reviewed and commented on by the community and Standard Names moderator.

[JonathanGregory]

Dear Aurore @abiardeau

For friction velocity in sea water, I suppose we ought to specify that it's a surface friction velocity, because the concept applies to the sea floor as well.

Best wishes

Jonathan

[abiardeau]

Dear @JonathanGregory

Thanks for your answer. You're right, should we say : eastward_friction_velocity_at_sea_water_surface ?

[JonathanGregory]

Yes, at_sea_water_surface is a phrase we've used before, so that would work. Another possibility is surface_eastward_friction_velocity_in_sea_water.

[abiardeau]

Thanks, both would work for us. If there is any preference from your side we we'll go with it

[efisher008]

Dear Aurore,

I have added your proposed name eastward_friction_velocity_in_sea_water to the editor, and will wait for more discussion on the format before proceeding (including the change to one of the above suggestions). It would be useful to have a description for this name to help clarify its use.

Best regards,
Ellie

[efisher008]

Hello Aurore @abiardeau,

Looking back at this issue, I am wondering if it would be more descriptive to use the form eastward_friction_velocity_at_sea_water_surface/northward_friction_velocity_at_sea_water_surface for the names. This would specify that it is a surface quantity as @JonathanGregory had mentioned, and there is some precedent in the standard names table for using at_sea_water_surface.

If you could provide a description for the names, that would be very useful. I have added the description for eastward ("Eastward" indicates a vector component which is positive when directed eastward (negative westward).") and northward (""Northward" indicates a vector component which is positive when directed northward (negative southward).") to them as a starting point.

Best wishes,
Ellie

[efisher008]

Hi Aurore @abiardeau,

I hope your summer is going well.
Now that your other batch of proposed standard names have been accepted, would you have any time to dedicate to progressing this proposal? It would be great to see it moving towards acceptance.

Best,
Ellie

[abiardeau]

Hello @efisher008
Thanks for your message.

I also prefer eastward_friction_velocity_at_sea_water_surface/northward_friction_velocity_at_sea_water_surface for the names.

About the definition, we propose this one, which is coherent with the definition of eastward_friction_velocity_in_air :

A velocity is a vector quantity.
"Eastward" indicates a vector component which is positive when directed eastward (negative westward).
Friction velocity is a reference ocean velocity derived from the relationship between ocean density and downward stress and is usually applied at a level close to the surface where stress is assumed to be independent of height and approximately proportional to the square of mean velocity.

[efisher008]

Hello @abiardeau,

Yes, this sounds reasonable. I have added those descriptions and altered the names in the editor, visible here:
eastward_friction_velocity_at_sea_water_surface - https://cfeditor.ceda.ac.uk/proposal/5340/edit
northward_friction_velocity_at_sea_water_surface - https://cfeditor.ceda.ac.uk/proposal/5419/edit

I have also added the definition of friction velocity in the context of air and sea water as stated to the CF phrasebank.

Are there any further comments on this issue? Otherwise I think we can start the 7-day countdown period to acceptance.

Best wishes,
Ellie

[abiardeau]

This is fine for me, thanks Ellie !

[github-actions]

This issue has had no activity in the last 30 days. Accordingly:

• If you proposed this issue or have contributed to the
  discussion, please reply to any outstanding concerns.
• If there has been little or no discussion, please comment
  on this issue, to assist with reaching a decision.
• If the proposal seems to have come to a consensus, please
  wait for the moderators to take the next steps towards
  acceptance.

Standard name moderators are also reminded to review @feggleton @japamment @efisher008