new and changed standard names for sea level to support IPCC AR7 and CMIP7

[JonathanGregory]

I would like to propose 11 new standard names and changes to 8 existing standard names, all relating to sea surface height and mean sea level. The aims of the proposal are

• To provide a set of standard names for quantities related to sea level that have been discussed and shown in previous IPCC assessment reports but which don't have standard names.
• To replace "average" with "mean" in the phrase "global average sea level change", because "mean" is more commonly used in the literature, as well as in CF vocabulary.
• To clarify the sign convention and definition in a few cases.

There are currently six other standard name proposals under discussion for sea level quantities, proposed by @abiardeau, @SwatiGehlot and @slawchune. The table below refers to the relevant open issues. In order to prevent confusion and complication, I think it would be better to delay discussion of my proposals until those ones are concluded, but I'm opening this issue now in case it's useful to see the set of names for related quantities. Comments are welcome, of course.

The following table shows the newly proposed names (new in the old standard name) column, the proposals for changed names, and for comparison some existing names that aren't proposed to be changed (unchanged). The new names will need definitions, which I'll fill in soon. I will base the definitions on those given by Gregory et al. (2019, https://dx.doi.org/10.1007/s10712-019-09525-z), which was used as a reference by the IPCC AR6. The column N in this table is the number of the quantity in that paper. All these quantities have m as canonical unit, except that the last one is m s-1. I attach here a PDF of the table, where it has a comments column as well. Note 16 Jul 2024 Table updated, but not the PDF.

N	standard name	old standard name
N2	sea_surface_height_above_reference_ellipsoid	unchanged
	sea_surface_height_above_geoid	unchanged
	sea_surface_height_above_geopotential_datum	unchanged
	sea_surface_height_above_mean_sea_level	unchanged
	square_of_sea_surface_height_above_geoid	unchanged
N3	mean_sea_level_height_above_reference_ellipsoid	new
−N4	sea_floor_depth_below_reference_ellipsoid	unchanged
N5	geoid_height_above_reference_ellipsoid	unchanged
N6	tidal_sea_surface_height_above_mean_sea_level	unchanged
N6	change_in_sea_floor_height_ above_reference_ellipsoid_ due_to_ocean_tide_loading	agreed in #41
−N7	change_in_sea_surface_height_ due_to_change_in_air_pressure	agreed in #38
−N7	change_in_mean_sea_level_ due_to_change_in_air_pressure	new
−N7	change in_sea_surface_height_ due_to_change_in_air_pressure_ and_wind_at_high_frequency	sea_surface_height_correction_ due_to_air_pressure_and_wind_at_high_frequency
−N7	change_in_sea_surface_height_ due_to_change_in_air_pressure_at_low_frequency	sea_surface_height_correction_ due_to_air_pressure_at_low_frequency
N10	sea_surface_[primary_|secondary_|tertiary_] swell_wave_significant_height	unchanged
N10	sea_surface_[wind_]wave_significant_height	unchanged
N10	sea_surface_wave_significant_period	unchanged
	sea_surface_height_above_reference_ellipsoid_ assuming_zero_air_pressure_anomaly_and_mean_tide	new
N11	ocean_dynamic_sea_level	agreed in #37
N13	change_in_ocean_dynamic_sea_level	new
N14	change_in_mean_sea_level_wrt_reference_ellipsoid	new
N15	change_in_mean_sea_level_wrt_solid_surface	agreed in #47
N16	[halo|thermo]steric_change_in_sea_surface_height	unchanged
N16	[halo|thermo]steric_change_in_mean_sea_level	unchanged
N17	global_mean_thermosteric_sea_level_change	global_average_thermosteric_sea_level_change
	global_mean_steric_sea_level_change	global_average_steric_sea_level_change
N18	manometric_change_in_sea_surface_height	new
N18	manometric_change_in_mean_sea_level	new
N19	global_mean_sea_level_change_ due_to_change_in_ocean_mass	agreed in #49
N20	sterodynamic_change_in_sea_level	new
N21	change_in_height_of_solid_surface_ wrt_reference_ellipsoid	new
N22	change_in_mean_sea_level_ due_to_change_in_geoid_and_solid_earth_deformation	new
	change_in_mean_sea_level_ due_to_change_in_global_ocean_mass_ and_geoid_and_solid_earth_deformation	new
N26	global_mean_sea_level_change	global_average_sea_level_change
N27	change_in_mean_sea_level_wrt_reference_ellipsoid with area: mean in cell_methods	same new name as for N14
	amplitude_of_global_mean_sea_level_change	amplitude_of_global_average_sea_level_change
	phase_of_global_mean_sea_level_change	phase_of_global_average_sea_level_change
	rate_of_global_mean_sea_level_change	tendency_of_global_average_sea_level_change

[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.

[efisher008]

Dear @JonathanGregory,

Thank you for your work in putting together this comprehensive list!

I've had a look through this list and tried to identify which of the "new" names you mentioned have just been accepted in issues #37, #38, #40, #41 and #49, and which were are being proposed for the first time here (so need adding to the editor).

Here are the newly accepted (i.e. existing) names I found from those issues:

• change_in_sea_surface_height_ due_to_change_in_air_pressure
• ocean_dynamic_sea_level
• tidal_sea_surface_height_above_mean_sea_level (first new name for tides, from #287)
• change_in_sea_floor_height_above_reference_ellipsoid_due_to_ocean_tide_loading (second new name for tides, from #288)
• global_average_steric_sea_level_change (question below)

Some points for discussion:

1. sea_surface_height_above_reference_ellipsoid_assuming_zero_air_pressure_anomaly_and_mean_tide hasn't been officially proposed in the issue Standard names: *Ocean surface elevation without the contributions of ocean tides nor atmospheric pressure forcing (invert barometer)* #37 (as mentioned in the table), but this can be added as a new name?

2. global_average_steric_sea_level_change has just been accepted in Standard names: *Global average sea level change due to water mass budget* #49. To be clear, you're proposing that this be changed to global_mean_steric_sea_level_change. Should it be published first, then an alias created, to retain the old name?
   The same goes for global_mean_sea_level_change_due_to_change_in_ocean_mass which is currently accepted under global_average_sea_level_change_due_to_change_in_ocean_mass.

Thanks again and looking forward to the reply.

Best regards,
Ellie

[JonathanGregory]

Dear Ellie

Thanks for your careful checking! That's helpful.

• tidal_sea_surface_height_above_mean_sea_level and global_average_steric_sea_level_change are existing standard names.

• I agree that ocean_dynamic_sea_level, change_in_sea_floor_height_above_reference_ellipsoid_due_to_ocean_tide_loading and change_in_sea_surface_height_due_to_change_in_air_pressure are new standard names that we've just accepted. Sorry about the hazardous space in the last of those, which was there only so that the table above folds itself into fewer lines.

• global_average_sea_level_change_due_to_change_in_ocean_mass is a newly accepted standard name, as you say. You are right that I would prefer global_mean_... in this and some existing names, but that's only my proposal, which we have not yet discussed. Since Stéphane and colleagues may start using this name immediately, we should maybe introduce an alias for it, even if that happens in the same version of the table as its initial appearance, but I don't know if that's the best thing to do.

• Stéphane and Aurore didn't need sea_surface_height_above_reference_ellipsoid_assuming_zero_air_pressure_anomaly_and_mean_tide in the end, but I'll keep it in this proposal.

I have updated the table at the top of the issue to accord with these points.

Best wishes

Jonathan

[taylor13]

I also vote for "mean", as opposed to "average".

[efisher008]

Dear Jonathan,

Thank you for pointing out the existing names tidal_sea_surface_height_above_mean_sea_level and global_average_steric_sea_level_change. These have been removed from the corresponding issues #40 and #49. I've removed the extra spaces from these names.

I will update the editor with proposed changes to the existing names now. The 10 new names are visible here:

• change_in_height_of_solid_surface_wrt_reference_ellipsoid: https://cfeditor.ceda.ac.uk/proposal/5366/edit
• manometric_change_in_mean_sea_level: https://cfeditor.ceda.ac.uk/proposal/5364/edit
• manometric_change_in_sea_surface_height: https://cfeditor.ceda.ac.uk/proposal/5363/edit
• change_in_mean_sea_level_wrt_reference_ellipsoid: https://cfeditor.ceda.ac.uk/proposal/5362/edit
• change_in_mean_sea_level_due_to_change_in_air_pressure: https://cfeditor.ceda.ac.uk/proposal/5360/edit
• change_in_ocean_dynamic_sea_level: https://cfeditor.ceda.ac.uk/proposal/5361/edit
• mean_sea_level_height_above_reference_ellipsoid: https://cfeditor.ceda.ac.uk/proposal/5359/edit
• sterodynamic_change_in_sea_level: https://cfeditor.ceda.ac.uk/proposal/5365/edit
• change_in_mean_sea_level_due_to_change_in_global_ocean_mass_and_geoid_and_solid_earth_deformation: https://cfeditor.ceda.ac.uk/proposal/5368/edit
• change_in_mean_sea_level_due_to_change_in_geoid_and_solid_earth_deformation: https://cfeditor.ceda.ac.uk/proposal/5367/edit

I've removed the extra spaces in your PDF from these names.

Best wishes,
Ellie

[efisher008]

Dear Jonathan,

The 8 changes to existing standard names are now in the CF editor as 'under discussion', see the entries below:

• change in_sea_surface_height_due_to_change_in_air_pressure_and_wind_at_high_frequency: https://cfeditor.ceda.ac.uk/proposal/5370/edit
• change_in_sea_surface_height_due_to_change_in_air_pressure_at_low_frequency: https://cfeditor.ceda.ac.uk/proposal/5371/edit
• global_mean_thermosteric_sea_level_change: https://cfeditor.ceda.ac.uk/proposal/5373/edit
• global_mean_steric_sea_level_change: https://cfeditor.ceda.ac.uk/proposal/5372/edit
• global_mean_sea_level_change: https://cfeditor.ceda.ac.uk/proposal/5374/edit
• amplitude_of_global_mean_sea_level_change: https://cfeditor.ceda.ac.uk/proposal/5375/edit
• phase_of_global_mean_sea_level_change: https://cfeditor.ceda.ac.uk/proposal/5376/edit
• rate_of_global_mean_sea_level_change: https://cfeditor.ceda.ac.uk/proposal/5377/edit

Please note I have not included the proposed change of global_average_sea_level_change_due_to_change_in_ocean_mass to global_mean_sea_level_change_due_to_change_in_ocean_mass at this time as this has yet to be published under the previous name and further discussion is needed around whether an alias would then be required.

Best wishes,
Ellie

[JonathanGregory]

Thanks, Ellie @efisher008. I will soon write down the reasons for proposing these new and changed names, and the descriptions for them.

[efisher008]

Hi @JonathanGregory,

@japamment and I have been looking through your list of new names and term changes. Thank you again for the detailed review. We had a few questions which you would hopefully be able to answer.

1. For your changes to the following names:
   sea_surface_height_correction_due_to_air_pressure_and_wind_at_high_frequency
   -> change in_sea_surface_height_ due_to_change_in_air_pressure_ and_wind_at_high_frequency
sea_surface_height_correction_due_to_air_pressure_and_wind_at_high_frequency
   -> change_in_sea_surface_height_ due_to_change_in_air_pressure_at_low_frequency
   Does the height_correction phrase in the "old" names refer to a numerical calculation component i.e. for a process not accounted for in a model? It is implied that this is the case in the name description, as opposed to the new phrase change_in...due_to reading as reflecting a change in the quantity due to a physical process. With this I am checking that the phrase usage is consistent with its application in context.

Note: If these names are changed they would also need to be changed in the descriptions for the existing altimeter_range_correction names as well.

2. Alison and I were unclear about the wording of the descriptions for sea_surface_height_correction names and how these relate to altimeter_range / the altimeter_range_correction names. From reading the description, it appears as though altimeter_range is clearly an instrumental measurement, for which a range correction might be appropriate (and there are standard names to this end). But for expressing variability in physical/modelled sea surface height quantities (where we are not aiming to quantify the instrumental error), is altimeter_range acting as a proxy for sea surface height, or should the text read that the correction should be added to a relevant sea_surface_height name instead? The sea_surface_height_correction quantity (equating to variation in sea surface topography) is not really correcting the distance between the instrument and the sea surface (i.e. the range), is it? If you could explain your thinking a little more here, it would be really appreciated.

3. For your names manometric_change_in_sea_surface_height and manometric_change_in_mean_sea_level:
   If these are not instantaneous quantities (i.e. they are time means, as stated in N18 of your 2019 paper), what is the period over which this quantity should be/is commonly calculated?

4. For manometric_change_in_mean_sea_level, is the manometric change calculation consistent with the "arbitrary" period over which the inputted "starting" value for mean sea level would be calculated (following the phrase mean_sea_level in names such as air_pressure_at_mean_sea_level": "Mean sea level" means the time mean of sea surface elevation at a given location over an arbitrary period sufficient to eliminate the tidal signals)? Are there implications for the quantity if the two averaging periods are different, or am I misunderstanding how the calculation is performed?

5. Would you be able to differentiate between manometric and barystatic sea level change to support mine and @japamment's understanding of these terms? From my perspective, manometric = addition of mass to a local column (?) of ocean water resulting in a (time averaged) increase/decrease in elevation of the sea surface height relative to a reference level, and barystatic = a change in sea level due to the addition to ocean volume from land/atmospheric water storage (e.g. through river outflow, ice melt & release from the atmospheric store)?
   A broader question might also be, how do we disambiguate this from other quantities in the standard name table (i.e. how to be explicit about the differences between manometric, barystatic etc. for non-specialists).

Please let me know if you would like me to clarify/rephrase any of these questions.

Best regards,
Ellie

[github-actions]

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