[CF-metadata] New standard names for NEMO ocean model output

[Kevin Marsh]

Hello all,
We are working with some NEMO ocean model output data and would like to request new standard names for a number of the NEMO variables.


The list of these variables is below, in the form:

NEMO variable name :

proposed CF Standard name

proposed definition. proposed units.

#----------------------------------------------------------------


sobpheig:

bottom_pressure_equivalent_height

Difference between the sea level height and the ocean steric height. (units = m)


somixhgt:

ocean_turbocline_depth

The turbocline depth is similar to the mixed layer depth but is estimated in models as the depth at which the vertical eddy diffusivity coefficient (resulting from the vertical physics alone) fall below a given value defined locally. (units = m)


vostheig:

ocean_steric_height

The steric measures the height by which a column of water with standard temperature T=0°C and salinity S=35.0 expands if its temperature and salinity are changed to the observed values (units = m)


vosthsal:

ocean_steric_thickness_due_to_salinity

Contribution of the salinity of the water column to the Ocean steric height. (units = m)


vosthtem:

ocean_steric_thickness_due_to_temperature

Contribution of the temperature of the water column to the Ocean steric height. (units = m)


vottrdmp:

temperature_profile_anomaly_correction

Correction term estimated as the deviation the local sea water potential temperature from an ocean model wrt to an observation-based climatology (eg World Ocean Database) multiplied by an user-specified relaxation coefficient. The relaxation coefficient depends on the timescale on which the correction is applied. (units = K/s)


vostrdmp:

practical_salinity_profile_anomaly_correction

Correction term estimated as the deviation the local sea water salinity from an ocean model wrt to an observation-based climatology (eg World
Ocean Database) multiplied by an user-specified relaxation coefficient. The relaxation coefficient depends on the timescale on which the correction is applied. (units = s-1)


sosal[300,700]:

integral_of_sea_water_practical_salinity_wrt_depth (units = m )

This quantity is calculated as the integral, of the sea water salinty wrt depth, over the specified layer of the ocean from the surface to the level indicated by the vertical coordinate or scalar coordinate variable. "integral_of_Y_wrt_X" means int Y dX. The data variable should have an axis for X specifying the limits of the integral as bounds. "wrt" means with respect to. "Layer" means any layer with upper and lower boundaries that have constant values in some vertical coordinate. There must be a vertical coordinate variable indicating the extent of the layer(s). If the layers are model layers, the vertical coordinate can be model_level_number, but it is recommended to specify a physical coordinate (in a scalar or auxiliary coordinate variable) as well. Depth is the vertical distance below the surface.

Practical Salinity, S_P, is a determination of the salinity of sea water, based on its electrical conductance. The measured conductance, corrected for temperature and pressure, is compared to the conductance of a standard potassium chloride solution, producing a value on the Practical Salinity Scale of 1978 (PSS-78). This name should not be used to describe salinity observations made before 1978, or ones not based on conductance measurements. Conversion of Practical Salinity to other precisely defined salinity measures should use the appropriate formulas specified by TEOS-10. Other standard names for precisely defined salinity quantities are sea_water_absolute_salinity (S_A); sea_water_preformed_salinity (S_*), sea_water_reference_salinity (S_R); sea_water_cox_salinity (S_C), used for salinity observations between 1967 and 1977; and sea_water_knudsen_salinity (S_K), used for salinity observations between 1901 and 1966. Salinity quantities that do not match any of the precise definitions should be given the more general standard name of sea_water_salinity. Reference: www.teos-10.org; Lewis, 1980 doi:10.1109/JOE.1980.1145448.


sosalbtm:

integral_of_sea_water_practical_salinity_wrt_total_depth

This quantity is calculated as the integral, of the sea water salinty, over of the ocean from the sea surface to the sea bed. "integral_of_Y_wrt_X" means int Y dX. The data variable should have an axis for X specifying the limits of the integral as bounds. "wrt" means with respect to. "Layer" means any layer with upper and lower boundaries that have constant values in some vertical coordinate. There must be a vertical coordinate variable indicating the extent of the layer(s). If the layers are model layers, the vertical coordinate can be model_level_number, but it is recommended to specify a physical coordinate (in a scalar or auxiliary coordinate variable) as well. Depth is the vertical distance below the surface.

Practical Salinity, S_P, is a determination of the salinity of sea water, based on its electrical conductance. The measured conductance, corrected for temperature and pressure, is compared to the conductance of a standard potassium chloride solution, producing a value on the Practical Salinity Scale of 1978 (PSS-78). This name should not be used to describe salinity observations made before 1978, or ones not based on conductance measurements. Conversion of Practical Salinity to other precisely defined salinity measures should use the appropriate formulas specified by TEOS-10. Other standard names for precisely defined salinity quantities are sea_water_absolute_salinity (S_A); sea_water_preformed_salinity (S_*), sea_water_reference_salinity (S_R); sea_water_cox_salinity (S_C), used for salinity observations between 1967 and 1977; and sea_water_knudsen_salinity (S_K), used for salinity observations between 1901 and 1966. Salinity quantities that do not match any of the precise definitions shoul d be given the more general standard name of sea_water_salinity. Reference: www.teos-10.org; Lewis, 1980 doi:10.1109/JOE.1980.1145448.

#----------------------------------------------------------------

Many Thanks,
Kevin

----------------------------------------------------
Kevin Marsh
ECMWF
----------------------------------------------------

[a***@stfc.ac.uk]

Dear Kevin,

Thank you for your proposals and apologies for the delay in responding. Your proposals have all been added to the CEDA vocabulary editor and can be viewed at the following link: http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=&proposerfilter=Marsh&descfilter=&unitfilter=&yearfilter=&commentfilter=&filter+and+display=Filter.

Please see below for my detailed comments on each name.

1. bottom_pressure_equivalent_height (m)
'Difference between the sea level height and the ocean steric height.'

Units of m are fine. Thinking first about the definition, in CF standard names we always use 'sea level' to mean mean sea level and 'steric' is defined in sea level change names as 'Global average steric sea level change is caused by changes in sea water density due to changes in temperature (thermosteric) and salinity (halosteric).' From this I would understand your quantity to be the difference between mean sea level and the local sea level due to the temperature and salinity of the water column. Is that correct?
If so, then as a non-ocean expert I find the name rather confusing and I'd prefer something more explicit, e.g., difference_of_ocean_steric_height_from_sea_level and we'd add a sentence to the definition explaining that 'steric height' refers to temperature and salinity effects on the density of the water column. Does that sound OK?

2. ocean_turbocline_depth (m)
'The turbocline depth is similar to the mixed layer depth but is estimated in models as the depth at which the vertical eddy diffusivity coefficient (resulting from the vertical physics alone) fall below a given value defined locally.

I think the name and units look fine. If you wanted to also be able to specify what value of the vertical eddy diffusivity coefficient was used to calculate the turbocline depth, it could be specified in a scalar coordinate variable and I'd suggest adding some words to the definition along those lines:
'The turbocline depth is similar to the mixed layer depth but is estimated in models as the depth at which the vertical eddy diffusivity coefficient (resulting from the vertical physics alone) fall below a given value defined locally. A coordinate variable or scalar coordinate variable with standard name ocean_vertical_diffusivity can be specified to indicate the value of the coefficient that was used to calculate the turbocline depth.'

ocean_vertical_diffusivity already exists as a standard name and is defined as ' "Vertical diffusivity" means the vertical component of diffusivity due to motion which is not resolved on the grid scale of the model.'

OK?

3. ocean_steric_height (m)
'The steric measures the height by which a column of water with standard temperature T=0°C and salinity S=35.0 expands if its temperature and salinity are changed to the observed values.'

To make this name consistent with proposals 4 and 5 below, I'd call this one ocean_steric_thickness because it's really referring to changes in the thickness of the water column rather than a height above any particular surface. Then the definition could read:
'The quantity with standard name ocean_steric_thickness is a measure of the change in thickness that would be undergone by a column of water of standard temperature T=0°C and practical salinity S=35.0 if its temperature and salinity were changed to the locally observed values. Thickness is the extent of a vertical column or layer.'

OK?

4. ocean_steric_thickness_due_to_salinity (m)
'Contribution of the salinity of the water column to the Ocean steric height.'

In an off list discussion prior to the submission of these names I suggested 'due_to_salinity' for this name, but I am now having a rethink because most often we use the phrase 'due_to' to refer to some process in the model (e.g. due_to_convection) which isn't quite the case here. Also, when reading through our existing steric sea level change names the definitions refer to thermosteric and halosteric components, which do apply to this case. Hence, I'd suggest changing the name to ocean_halosteric_thickness which also has the advantage of being shorter. Then the definition could read:
'The quantity with standard name ocean_halosteric_thickness is a measure of the change in thickness that would be undergone by a column of water of standard temperature T=0°C and practical salinity S=35.0 if its salinity were changed to the locally observed value. Thickness is the extent of a vertical column or layer. There are also standard names for ocean_steric_thickness and ocean_halosteric_thickness.'

OK?

5. ocean_steric_thickness_due_to_temperature (m)
'Contribution of the temperature of the water column to the Ocean steric height.'
As per my comments on proposal 4, I suggest changing this name to 'ocean_thermosteric_thickness' and then the definition would be:
'The quantity with standard name ocean_thermosteric_thickness is a measure of the change in thickness that would be undergone by a column of water of standard temperature T=0°C and practical salinity S=35.0 if its temperature were changed to the locally observed value. Thickness is the extent of a vertical column or layer. There are also standard names for ocean_steric_thickness and ocean_thermosteric_thickness.'

OK?

6. temperature_profile_anomaly_correction (K s-1)
'Correction term estimated as the deviation the local sea water potential temperature from an ocean model wrt to an observation-based climatology (eg World Ocean Database) multiplied by an user-specified relaxation coefficient. The relaxation coefficient depends on the timescale on which the correction is applied.'

I think the pattern of this name is consistent with existing anomaly and correction names (although we've never had them both in one name before!). The units are fine. Am I correct in thinking that the relaxation coefficient is calculated at each level in the profile? If so, then that should be explained in the definition.

7. practical_salinity_profile_anomaly_correction (s-1)
'Correction term estimated as the deviation the local sea water salinity from an ocean model wrt to an observation-based climatology (eg World Ocean Database) multiplied by an user-specified relaxation coefficient. The relaxation coefficient depends on the timescale on which the correction is applied.'

My comments on proposal 6 also apply to this one. The definition should say 'practical salinity' rather than just 'salinity' for consistency with the name. For completeness, we could then also add the text from the definition of sea_water_practical_salinity as I see you have already done in proposals 8 and 9.

I'd like to take proposals 8 and 9 together as they are closely related:
8. integral_of_sea_water_practical_salinity_wrt_depth (m)
'This quantity is calculated as the integral, of the sea water salinty wrt depth, over the specified layer of the ocean from the surface to the level indicated by the vertical coordinate or scalar coordinate variable. "integral_of_Y_wrt_X" means int Y dX. The data variable should have an axis for X specifying the limits of the integral as bounds. "wrt" means with respect to. "Layer" means any layer with upper and lower boundaries that have constant values in some vertical coordinate. There must be a vertical coordinate variable indicating the extent of the layer(s). If the layers are model layers, the vertical coordinate can be model_level_number, but it is recommended to specify a physical coordinate (in a scalar or auxiliary coordinate variable) as well. Depth is the vertical distance below the surface.

Practical Salinity, S_P, is a determination of the salinity of sea water, based on its electrical conductance. The measured conductance, corrected for temperature and pressure, is compared to the conductance of a standard potassium chloride solution, producing a value on the Practical Salinity Scale of 1978 (PSS-78). This name should not be used to describe salinity observations made before 1978, or ones not based on conductance measurements. Conversion of Practical Salinity to other precisely defined salinity measures should use the appropriate formulas specified by TEOS-10. Other standard names for precisely defined salinity quantities are sea_water_absolute_salinity (S_A); sea_water_preformed_salinity (S_*), sea_water_reference_salinity (S_R); sea_water_cox_salinity (S_C), used for salinity observations between 1967 and 1977; and sea_water_knudsen_salinity (S_K), used for salinity observations between 1901 and 1966. Salinity quantities that do not match any of the precise definitions should be given the more general standard name of sea_water_salinity. Reference: www.teos-10.org; Lewis, 1980 doi:10.1109/JOE.1980.1145448.'

9. integral_of_sea_water_practical_salinity_wrt_total_depth (m)
'This quantity is calculated as the integral, of the sea water salinty, over of the ocean from the sea surface to the sea bed. "integral_of_Y_wrt_X" means int Y dX. The data variable should have an axis for X specifying the limits of the integral as bounds. "wrt" means with respect to. "Layer" means any layer with upper and lower boundaries that have constant values in some vertical coordinate. There must be a vertical coordinate variable indicating the extent of the layer(s). If the layers are model layers, the vertical coordinate can be model_level_number, but it is recommended to specify a physical coordinate (in a scalar or auxiliary coordinate variable) as well. Depth is the vertical distance below the surface.

Practical Salinity, S_P, is a determination of the salinity of sea water, based on its electrical conductance. The measured conductance, corrected for temperature and pressure, is compared to the conductance of a standard potassium chloride solution, producing a value on the Practical Salinity Scale of 1978 (PSS-78). This name should not be used to describe salinity observations made before 1978, or ones not based on conductance measurements. Conversion of Practical Salinity to other precisely defined salinity measures should use the appropriate formulas specified by TEOS-10. Other standard names for precisely defined salinity quantities are sea_water_absolute_salinity (S_A); sea_water_preformed_salinity (S_*), sea_water_reference_salinity (S_R); sea_water_cox_salinity (S_C), used for salinity observations between 1967 and 1977; and sea_water_knudsen_salinity (S_K), used for salinity observations between 1901 and 1966. Salinity quantities that do not match any of the precise definitions shoul d be given the more general standard name of sea_water_salinity. Reference: www.teos-10.org; Lewis, 1980 doi:10.1109/JOE.1980.1145448.

Essentially, proposals 8 and 9 are describing the same concept with the only difference being that the first is integrated over a layer from the sea surface to some specified depth while 9 is integrated over the whole ocean depth. We have existing names that refer to atmosphere and ocean layers (also permafrost and soil layers) but we generally try to avoid using the word 'total' in standard names. Based on these considerations I'd suggest that proposal 8 should be integral_of_sea_water_practical_salinity_wrt_depth_in_ocean_layer and proposal 9 should be ocean_integral_of_sea_water_practical_salinity_wrt_to_depth where the use of the word 'ocean' implies integration over the entire water column, consistent with its use in existing names. What do you think?

Best wishes,
Alison

------
Alison Pamment Tel: [phone]
Centre for Environmental Data Analysis Email: ***@stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Campus, Didcot, OX11 0QX, U.K.

[Antonio S. Cofiño]

Hi Alison and Kevin,

Post by a***@stfc.ac.uk
Essentially, proposals 8 and 9 are describing the same concept with the only difference being that the first is integrated over a layer from the sea surface to some specified depth while 9 is integrated over the whole ocean depth. We have existing names that refer to atmosphere and ocean layers (also permafrost and soil layers) but we generally try to avoid using the word 'total' in standard names. Based on these considerations I'd suggest that proposal 8 should be integral_of_sea_water_practical_salinity_wrt_depth_in_ocean_layer and proposal 9 should be ocean_integral_of_sea_water_practical_salinity_wrt_to_depth where the use of the word 'ocean' implies integration over the entire water column, consistent with its use in existing names. What do you think?

[@Alison, a minor typo is the 'to' on
ocean_integral_of_sea_water_practical_salinity_wrt_to_depth it's already
in the 'wrt']

Just to mention that for NEMO there are already (from 2008, see [1])
some standard_name definitions which are not coherent with Alison's
proposal about the layer:

integral_of_sea_water_potential_temperature_wrt_depth_expressed_as_heat_content

Post by a***@stfc.ac.uk
"integral_of_Y_wrt_X" means int Y dX. The data variable should have an
axis for X specifying the limits of the integral as bounds. "wrt"
means with respect to. "expressed_as_heat_content" means that this
quantity is calculated as the (assumed constant) specific heat
capacity times density of sea water multiplied by the integral, over
the specified layer of the ocean, of the sea water potential
temperature wrt depth.

and following Alison's suggestion it should be read as:

integral_of_sea_water_potential_temperature_wrt_depth_in_ocean_layer_expressed_as_heat_content

should be propose new one standard_name?

Post by a***@stfc.ac.uk
9. integral_of_sea_water_practical_salinity_wrt_total_depth (m)
'This quantity is calculated as the integral, of the sea water salinty, over of the ocean from the sea surface to the sea bed. "integral_of_Y_wrt_X" means int Y dX. The data variable should have an axis for X specifying the limits of the integral as bounds. "wrt" means with respect to. "Layer" means any layer with upper and lower boundaries that have constant values in some vertical coordinate. There must be a vertical coordinate variable indicating the extent of the layer(s). If the layers are model layers, the vertical coordinate can be model_level_number, but it is recommended to specify a physical coordinate (in a scalar or auxiliary coordinate variable) as well. Depth is the vertical distance below the surface.

what ever is the final standard_name, it would convenient to remove axis requirement for the X (i.e. depth). The reason is because the interval limits (bounds) are not constant along every grid point. What do you think?Best regards

Antonio

[1] http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2008/052500.html

Post by a***@stfc.ac.uk
Best wishes,
Alison
------
Alison Pamment Tel: [phone]
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Campus, Didcot, OX11 0QX, U.K.
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--
Antonio S. Cofiño
Associate Professor and Researcher
Grupo de Meteorología de Santander
Dep. of Applied Mathematics and Computer Sciences
Universidad de Cantabria (Spain)

Academic Visitor
National Centre for Atmospheric Science
Department of Meteorology
School of Mathematical, Physical and Computational Sciences
University of Reading (UK)

http://antonio.cofino.es