Standard names: *suspended sediment concentration

[rlepper91]

Proposer's name Robert Lepper

Date 01 October 2025

- Term
sea_water_suspended_sediment_concentration
related: sea_surface_suspended_sediment_concentration and related: sea_water_suspended_sediment_concentration_at_sea_floor

- Description In the coastal sea, sediments can either be transported near the sea floor (bedload transport) or within the water body (suspended sediments). When modeling estuarine, riverine or coastal systems in hydrodynamic models, sediments are often of interest and their presence in the water body is expressed as a concentration. This parameter can physically be compared to sea_water_salinity and is essential in modeling near the coast. As the suspended sediment concentration is depth-dependent and can also be derived from satellite imagery or measured in the water column, it makes sense to include sea_surface and at_sea_floor. The existing standard name mass_concentration_of_suspended_matter_in_sea_water is misleading because suspended matter may also include organics or algae.

- Units kg m-3

[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.

[github-actions]

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

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

[eileenhertwig-dkrz]

Dear @rlepper91,

I have added your three new terms to the CF standard names editor, but I would propose some changes to be more in line with how standard names are usually constructed. I have also added some descriptions:

1. sea_water_suspended_sediment_concentration -> mass_concentration_of_suspended_sediment: Suspended sediment means undissolved solid particles. "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y.
   Unit: kg m-3
   (https://cfeditor.ceda.ac.uk/proposal/5741)
2. sea_surface_suspended_sediment_concentration -> mass_concentration_of_suspended_sediment_in_sea_water_at_sea_water_surface: Suspended sediment means undissolved solid particles. The phrase "sea water surface" means the upper boundary of the liquid portion of an ocean or sea, including the boundary to floating ice if present. "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y.
   Unit: kg m-3
   (https://cfeditor.ceda.ac.uk/proposal/5742/)
3. sea_water_suspended_sediment_concentration_at_sea_floor -> mass_concentration_of_suspended_sediment_in_sea_water_at_sea_floor: Suspended sediment means undissolved solid particles. The surface called "sea floor" means the lower boundary of the ocean. The parameter at the sea floor is that adjacent to the ocean bottom, which would be the deepest grid cell in an ocean model and within the benthic boundary layer for measurements. "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y.
   Unit: kg m-3
   (https://cfeditor.ceda.ac.uk/proposal/5743)

Do you have any comments? Are you happy with these changes and descriptions?

Best regards,
Eileen

[JonathanGregory]

Dear Robert @rlepper91 and Eileen @eileenhertwig-dkrz

Sorry you had to wait so long for a response, Robert, and thank you, Eileen, for answering.

I notice that there is an existing standard name mass_concentration_of_suspended_matter_in_sea_water - the only one with the word suspended, in fact. Is the same thing as "suspended sediment" now proposed? If it is, the existing name should be suitable for "mass concentration of suspended sediment", which also needs "in sea water", like 2 and 3. We could add something like "suspended matter may also be called suspended sediment" to its description, to make it easier to find. If it's not the same, we need some clarification of what "suspended matter" does not count as "suspended sediment".

I agree with Eileen's patterns for 2 and 3.

Best wishes

Jonathan

[eileenhertwig-dkrz]

Dear @JonathanGregory ,

You are of course right that mass_concentration_of_suspended_sediment would also need _in_sea_water like 2 and 3. I will change it in the CF editor, but let's hear what @rlepper91 says about mass_concentration_of_suspended_matter_in_sea_water and if this would also fit their purpose.

Best regards,
Eileen

[rlepper91]

Dear @eileenhertwig-dkrz , dear @JonathanGregory ,

thanks a lot for your suggestions. After internal review, we agree with mass_concentration_of_suspended_matter_in_sea_water (side note: matter can always be suspended in fresh or brackish water but let's not make it more complicated than it is). We would also like to see at_sea_floor or at sea_water_surface added to the CF conventions, if possible. The info that matter maybe also be sediment would definitely be appreciated.

Regards,
Robert

[ChrisBarker-NOAA]

side note: matter can always be suspended in fresh or brackish water but let's not make it more complicated than it is

This has come up in other contexts -- if these were brand new names, I"d advocate for some less-specific term, like "water".

But it seems the proposal is to add a couple more locations to an existing name, so no need to revisit that now.

I am a bit concerned with at_sea_floor or at sea_water_surface: we had a big discussion recently on antoher name, and it's tricky, cause you will get very different values depending on exactly how far from the surface or sea floor you measure / how thick a layer you are averaging over.

I don't see any other "at_sea_surface" names existing, though a lot of "surface".

Is there an existing name that has a similar concept of "at surface" or "at sea floor" ?

And/or are these terms commonly used and understood in your field?

[rlepper91]

I would think that these terms are understood as at (or near) sea surface/floor as it is very model dependent on how close one can model this entity. Internally, we used the terms "bottom" and "top" to refer to the location in the water column but I was unable to find an equivalent naming in the CF-conventions.

[JonathanGregory]

sea_water_surface would mean the top of the liquid water, thus the interface with air or floating ice, whichever is there. Is that what you intend?

I think _at_sea_floor is fine if it's not significantly dependent with how far above you are from the sea floor. We do have several existing standard names with this phrase e.g. sea_water_temperature_at_sea_floor.