Standard names: *how to interpret names for certain tide parameters*

[matthiaslankhorst]

Hi,

looking at the following established standard names, I have a clarification question, below:

sea_surface_height_amplitude_due_to_earth_tide
sea_surface_height_amplitude_due_to_equilibrium_ocean_tide
sea_surface_height_amplitude_due_to_geocentric_ocean_tide
sea_surface_height_amplitude_due_to_non_equilibrium_ocean_tide
sea_surface_height_amplitude_due_to_pole_tide

What is meant by "amplitude"? If I have a time series of any of these properties, e.g. a time series of the solid-earth tide at a given location, is this standard name appropriate for the data variable that holds the entire time series, or only for the single number calculated as maximum minus minimum of my time series?

There seem to be no equivalent standard names without the "amplitude" wording.

What I really want is this: I have data with some of these variables, expressed as time series at several stations. I want to know whether I can use these standard names for the time series. If not, I am just as happy describing my data using "long_name" and without a "standard_name". Just want to make sure I am doing it right.

Regards, Matthias

--

---

Dr. Matthias Lankhorst
Scripps Institution of Oceanography
9500 Gilman Drive, Mail Code 0230
La Jolla, CA 92093-0230
USA

Phone: +1 858 822 5013
E-Mail: mlankhorst@ucsd.edu

[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 @matthiaslankhorst

That's a good question. There is one other existing standard name which mentions amplitude viz. amplitude_of_global_average_sea_level_change, whose description says, "Amplitude is the magnitude of a wave modelled by a sinusoidal function." I think that's the idea in the sea_surface_height_amplitude_due_toX standard names, and I'd suggest to @eileenhertwig-dkrz et al. that it would be useful to copy the definition of amplitude into their descriptions. Also, it would be better not to mention "wave" in these sea level quantities, because they're not thought of as waves. We could say, "Amplitude is the magnitude of a periodic variation modelled by a sinusoidal function." What do you think? For maximum minus minimum, CF has the cell method of range.

If my interpretation is correct, for your purpose you need corresponding new standard names. I would suggest change_in_sea_surface_height_due_to_X, because SSH is always wrt some datum. It doesn't have an "absolute" meaning, so "SSH due to X" would seem unsatisfactory to me. Including change_in would be consistent with the existing standard name change_in_sea_surface_height_due_to_change_in_air_pressure.

Best wishes

Jonathan

[matthiaslankhorst]

Thanks, that was a thoughtful response which basically confirms that I should not be using the "...amplitude..." standard names for my time series.

I am listing the variables that I am dealing with below. These are from moored buoys that sway about in a watch circle of multiple miles diameter. The buoys have precision GPS devices to measure sea surface height, and most of these variables are ancillary information (from models) interpolated to the actual buoy positions to help interpret the sea surface height data. I.e. even things like geoid and mean sea surface height are given as time series with non-constant values (because the buoy positions change over time).

I consider this a one-off, so my first question is: Is it even worth creating new standard names for this use case? I can describe the data using "long_name" instead.

• Buoy measurements of SSH. I am using the existing standard name, sea_surface_height_above_reference_ellipsoid, no change needed.
• Geoid, I am using the existing standard name, geoid_height_above_reference_ellipsoid, no change needed.
• Load tide, I am using the existing standard name, change_in_sea_floor_height_above_reference_ellipsoid_due_to_ocean_tide_loading (that's a mouthful!)
• Ocean tide, I will use existing standard name, tidal_sea_surface_height_above_mean_sea_level
• Mean sea surface height, I am unsure whether I should use the existing standard name height_above_reference_ellipsoid (because it does not specify the height of what???). I could not figure out proper cell methods either (which would denote that the data are a mean in time, but since my buoy changes location, it sees changes with time).
• Solid earth tide, I will not use sea_surface_height_amplitude_due_to_earth_tide. Jonathan's suggestion for a new name (if we even want it) would thus be, change_in_sea_surface_height_due_to_earth_tide.
• Pole tide, I will not use sea_surface_height_amplitude_due_to_pole_tide. Again, we might consider creating change_in_sea_surface_height_due_to_pole_tide.

Any advice on the last three bullets is welcome!

Thanks, Matthias

[JonathanGregory]

Dear @matthiaslankhorst

I think it's fine for those quantities to be spatiotemporally dependent with appropriate standard names. They're all geophysically well-defined quantities.

For mean SSH, you can again use the existing name sea_surface_height_above_reference_ellipsoid. To indicate that it's a time-mean, you would put cell_methods="TIME: mean", where TIME is a scalar or size-1 time coordinate variable with bounds to indicate the time period. Is that what you need?

If so, it appears you need to propose just two standard names, which follow existing patterns.

Best wishes

Jonathan

[eileenhertwig-dkrz]

Dear @matthiaslankhorst and @JonathanGregory,

To summarize: the definition of "amplitude" needs to be changed, which implies that the description of 6 existing terms need to changed as well:

1. amplitude_of_global_average_sea_level_change: https://cfeditor.ceda.ac.uk/proposal/5816/
   Global average sea level change is due to change in volume of the water in the ocean, caused by mass and/or density change, or to change in the volume of the ocean basins, caused by tectonics etc. It is sometimes called "eustatic", which is a term that also has other definitions. It differs from the change in the global average sea surface height relative to the centre of the Earth by the global average vertical movement of the ocean floor. Zero sea level change is an arbitrary level. Amplitude is the magnitude of a periodic variation modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. Because global average sea level change quantifies the change in volume of the world ocean, it is not calculated necessarily by considering local changes in mean sea level.
   Unit: m
2. sea_surface_height_amplitude_due_to_earth_tide: https://cfeditor.ceda.ac.uk/proposal/5817/
   "Sea surface height" is a time-varying quantity. Amplitude is the magnitude of a periodic variation modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Tides are a significant contributor to the observed sea surface height; earth tide means the solid earth tide.
   Unit: m
3. sea_surface_height_amplitude_due_to_equilibrium_ocean_tide: https://cfeditor.ceda.ac.uk/proposal/5818/
   "Sea surface height" is a time-varying quantity. Amplitude is the magnitude of a periodic variation modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Tides are a significant contributor to the observed sea surface height; equilibrium ocean tide refers to the long period ocean tide.
   Unit: m
4. sea_surface_height_amplitude_due_to_geocentric_ocean_tide: https://cfeditor.ceda.ac.uk/proposal/5819/
   "Sea surface height" is a time-varying quantity. Amplitude is the magnitude of a periodic variation modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Tides are a significant contributor to the observed sea surface height; geocentric ocean tide means the sum total of ocean tide and load tide.
   Unit: m
5. sea_surface_height_amplitude_due_to_non_equilibrium_ocean_tide: https://cfeditor.ceda.ac.uk/proposal/5820/
   "Sea surface height" is a time-varying quantity. Amplitude is the magnitude of a periodic variation modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Tides are a significant contributor to the observed sea surface height; non equilibrium ocean tide refers to the long period ocean tide.
   Unit: m
6. sea_surface_height_amplitude_due_to_pole_tide: https://cfeditor.ceda.ac.uk/proposal/5821/
   "Sea surface height" is a time-varying quantity. Amplitude is the magnitude of a periodic variation modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Tides are a significant contributor to the observed sea surface height; the pole tide occurs due to variations in the earth's rotation.
   Unit: m

Furthermore, 2 new standard names are needed, which follow already existing patterns:

1. change_in_sea_surface_height_due_to_earth_tide: https://cfeditor.ceda.ac.uk/proposal/5822/
   "Sea surface height" is a time-varying quantity. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Tides are a significant contributor to the observed sea surface height; earth tide means the solid earth tide.
   Unit: m
2. change_in_sea_surface_height_due_to_pole_tide: https://cfeditor.ceda.ac.uk/proposal/5823/
   "Sea surface height" is a time-varying quantity. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Tides are a significant contributor to the observed sea surface height; the pole tide occurs due to variations in the earth's rotation.
   Unit: m

Does everything look alright?

Best regards,
Eileen

[JonathanGregory]

Yes, I think that's right. Thanks, @eileenhertwig-dkrz

[eileenhertwig-dkrz]

Thanks @JonathanGregory.

@matthiaslankhorst are you happy with the two new terms as they are now?

Best regards,
Eileen

[matthiaslankhorst]

Hi, yes, these are great and meet all my needs. Sorry for not responding sooner, I am out at sea, Thank you for moving this along so quickly! Regards, Matthias

…

On Wed, Apr 15, 2026 at 4:32 AM eileenhertwig-dkrz ***@***.***> wrote: *eileenhertwig-dkrz* left a comment (cf-convention/vocabularies#304) <https://urldefense.com/v3/__https://github.com/cf-convention/vocabularies/issues/304*issuecomment-4251623158__;Iw!!Mih3wA!E4m5sPthNdNMHfbqnaSgIIf5Mb3tTt-Mskk8PmN81KyMZ-CjJvTVKlzBrmHcNqdG1QpIxcMUgYZ6q03SJ7j8hAJ3dA$> Thanks @JonathanGregory <https://urldefense.com/v3/__https://github.com/JonathanGregory__;!!Mih3wA!E4m5sPthNdNMHfbqnaSgIIf5Mb3tTt-Mskk8PmN81KyMZ-CjJvTVKlzBrmHcNqdG1QpIxcMUgYZ6q03SJ7jwD1ZE8A$> . @matthiaslankhorst <https://urldefense.com/v3/__https://github.com/matthiaslankhorst__;!!Mih3wA!E4m5sPthNdNMHfbqnaSgIIf5Mb3tTt-Mskk8PmN81KyMZ-CjJvTVKlzBrmHcNqdG1QpIxcMUgYZ6q03SJ7jFRdbURA$> are you happy with the two new terms as they are now? Best regards, Eileen — Reply to this email directly, view it on GitHub <https://urldefense.com/v3/__https://github.com/cf-convention/vocabularies/issues/304*issuecomment-4251623158__;Iw!!Mih3wA!E4m5sPthNdNMHfbqnaSgIIf5Mb3tTt-Mskk8PmN81KyMZ-CjJvTVKlzBrmHcNqdG1QpIxcMUgYZ6q03SJ7j8hAJ3dA$>, or unsubscribe <https://urldefense.com/v3/__https://github.com/notifications/unsubscribe-auth/AEWDTFIXENQL2TX6TFGF5XD4V5XOPAVCNFSM6AAAAACW7HBTJ2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DENJRGYZDGMJVHA__;!!Mih3wA!E4m5sPthNdNMHfbqnaSgIIf5Mb3tTt-Mskk8PmN81KyMZ-CjJvTVKlzBrmHcNqdG1QpIxcMUgYZ6q03SJ7jLCLggsw$> . You are receiving this because you were mentioned.Message ID: ***@***.***>

--

_______________________________________ Dr. Matthias Lankhorst Scripps Institution of Oceanography 9500 Gilman Drive, Mail Code 0230 La Jolla, CA 92093-0230 USA Phone: +1 858 822 5013 E-Mail: ***@***.***

[eileenhertwig-dkrz]

Thanks for your answer!

I think, everything is taken care of now and I can put the 7-days label on this issue. If no more comments are received in the next 7 days, these 2 new terms will be accepted as well as the new descriptions for the existing terms.

Best regards,
Eileen