[CF-metadata] Some standard name updates to improve consistency.

Alison Pamment - UKRI STFC alison.pamment at stfc.ac.uk
Thu Apr 25 12:17:01 MDT 2019

Dear Martin,

Thank you for this set of proposals. I am always in favour of improving consistency in standard names - it makes them easier both for users to find and for us to maintain.

1. You are right that the aerosol names should say "particles".

There was a lot of discussion of aerosol names in 2014 and Markus Fiebig pointed out that the text book definition of  "aerosol" means both aerosol particles and the gas that carries them. Standard names are usually concerned with the particulate component so it was agreed that both new and existing names should say "aerosol_particles" rather than simply "aerosol". Aliases were made for about 200 existing names, but it looks like a few were missed.

The following 3 aliases are accepted and will be added in the May update of the standard name table.

tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_expressed_as_sulfur_due_to_wet_deposition -> tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_particles_expressed_as_sulfur_due_to_wet_deposition
mass_fraction_of_mercury_dry_aerosol_in_air -> mass_fraction_of_mercury_dry_aerosol_particles_in_air
tendency_of_atmosphere_mass_content_of_mercury_dry_aerosol_due_to_emission ->  tendency_of_atmosphere_mass_content_of_mercury_dry_aerosol_particles_due_to_emission

2. Primary production vs. primary productivity

Roy's interpretation is correct: in standard names "productivity" is defined as "production per unit area". The land names say "productivity" because they are all quantifying the production of biomass in the horizontal area of a grid cell, whereas the ocean names are referring to production in a volume element. The ocean name definitions all say 'In the oceans, carbon production per unit volume is often found at a number of depths at a given horizontal location. That quantity can then be integrated to calculate production per unit area at the location. Standard names for production per unit area use the term "productivity." 

I think our existing names are using the appropriate term and units consistently throughout.

3. aerodynamic_resistance

This name again dates back to our aerosol discussions of 2014. It was originally proposed by Brigitte Koffi-Lefeivre for the HTAP2 project. Many names were discussed over a protracted period, but the aerodynamic_resistance discussion starts here: http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2014/017813.html (it appears as item 7 in some of the longer emails). At the time, I suggested names such as aerodynamic_drag_on_turbulent_deposition_of_aerosol_particles or aerodynamic_resistance_to_turbulent_deposition but it was argued (http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2014/017841.html) that simply "aerodynamic_resistance" was the term most generally used.

I agree that the name seems more specialized than the generic definition in the AMS glossary and your proposal of aerodynamic_resistance_of_planetary_boundary_layer is consistent with the standard name definition which emerged from the original discussion. My gut feeling is that it would be useful to do a bit more research into this one - I will get hold of a copy of the paper referenced in the definition. If any aerosol experts can help, that would also be much appreciated!

4. Litter and soil

Agreed - and thanks for spotting this! We should definitely have a standard order for listing the terms.

The following alias is accepted and will be added in the May update of the standard name table.

carbon_mass_flux_into_soil_and_litter_due_to_anthropogenic_land_use_or_land_cover_change -> carbon_mass_flux_into_litter_and_soil_due_to_anthropogenic_land_use_or_land_cover_change

5. Products

Agreed - and thanks again. 

The duplicate terms shouldn't simply disappear, so I will make aliases as follows:

1 and 2. product_of_specific_humidity_and_omega -> product_of_specific_humidity_and_lagrangian_tendency_of_air_pressure AND product_of_omega_and_specific_humidity -> product_of_specific_humidity_and_lagrangian_tendency_of_air_pressure
3. product_of_eastward_wind_and_omega -> product_of_eastward_wind_and_lagrangian_tendency_of_air_pressure
4. product_of_northward_wind_and_omega -> product_of_northward_wind_and_lagrangian_tendency_of_air_pressure
5 and 6. product_of_air_temperature_and_omega -> product_of_air_temperature_and_lagrangian_tendency_of_air_pressure AND product_of_omega_and_air_temperature -> product_of_air_temperature_and_lagrangian_tendency_of_air_pressure
7. product_of_geopotential_height_and_omega -> product_of_geopotential_height_and_lagrangian_tendency_of_air_pressure

These changes are accepted and will be added in the May update of the standard name table.

6. Use of "net_downward" in aerosol indirect radiative effect terms.

I agree that radiative forcing and radiative effect names should be treated consistently, and that aerosol radiative effect should be treated consistently with cloud radiative effect. I agree also with your statement  that "the sign convention is assumed to be that positive forcing/radiative effect is equivalent to a downward radiative flux" . This is certainly consistent with general usage in the literature.

As you point out, only the four ambient aerosol radiative effect names mention the sign convention. The other existing names make no mention of it and neither do their definitions. This strikes me as an omission. I'm fine with taking net_downward out of the aerosol names, but for absolute clarity I think we should add something to the definitions of all the radiative forcing and effect names. I suggest we add 'A positive radiative forcing or radiative effect is  equivalent to a downward radiative flux and contributes to a warming of the earth system.' What do you think?

7. Use of "downwelling" in attenuation coefficients

I agree with Karl's comment about this one, and with Martin's response. In the absence of more detailed information about how this name is being used, I think we are agreed not to change it.

8. Specification of air vs. ocean

I agree that backscattering_ratio should become backscattering_ratio_in_air.

This alias is accepted and will be added in the May update of the standard name table.

We also have the name histogram_of_backscattering_ratio_over_height_above_reference_ellipsoid. Again it is clearly an "in_air" quantity, so perhaps for consistency we should also make the following alias:
histogram_of_backscattering_ratio_over_height_above_reference_ellipsoid -> histogram_of_backscattering_ratio_in_air_over_height_above_reference_ellipsoid.

On the other hand, the fact that it is above_reference_ellipsoid already implies that this is an air quantity rather than a sea water one. What do you think?

9. cloud liquid water particle vs. particles and aerosol particle vs. particles.

We try to write standard names that are grammatically correct in English, so we need to retain the flexibility to use singular and plural versions of nouns where strictly necessary, but I agree that we should be consistent in deciding which to use in a particular circumstance. In the case of particle/particles I think we can standardize on the plural, at least for existing names.

In the cloud names, certainly "particles" should be used in all the number concentrations. Up to now, we've used the singular in effective radius names although I'm not sure why! These apply to a size distribution of many particles, so I think it actually makes more sense to use the plural.

The following aliases are accepted and will be included in the May update of the standard name table.

effective_radius_of_cloud_liquid_water_particle -> effective_radius_of_cloud_liquid_water_particles
effective_radius_of_cloud_liquid_water_particle_at_liquid_water_cloud_top -> effective_radius_of_cloud_liquid_water_particles_at_liquid_water_cloud_top
effective_radius_of_convective_cloud_liquid_water_particle -> effective_radius_of_convective_cloud_liquid_water_particles
effective_radius_of_convective_cloud_liquid_water_particle_at_convective_liquid_water_cloud_top -> effective_radius_of_convective_cloud_liquid_water_particles_at_convective_liquid_water_cloud_top
effective_radius_of_stratiform_cloud_liquid_water_particle -> effective_radius_of_stratiform_cloud_liquid_water_particles
effective_radius_of_stratiform_cloud_liquid_water_particle_at_stratiform_liquid_water_cloud_top -> effective_radius_of_stratiform_cloud_liquid_water_particles_at_stratiform_liquid_water_cloud_top
number_concentration_of_convective_cloud_liquid_water_particle_at_convective_liquid_water_cloud_top -> number_concentration_of_convective_cloud_liquid_water_particles_at_convective_liquid_water_cloud_top
number_concentration_of_stratiform_cloud_liquid_water_particle_at_stratiform_liquid_water_cloud_top -> number_concentration_of_stratiform_cloud_liquid_water_particles_at_stratiform_liquid_water_cloud_top

There are a number of other cloud particle effective radius names, which should be changed at the same time:
effective_radius_of_convective_cloud_ice_particle -> effective_radius_of_convective_cloud_ice_particles
effective_radius_of_convective_cloud_rain_particle -> effective_radius_of_convective_cloud_rain_particles
effective_radius_of_convective_cloud_snow_particle -> effective_radius_of_convective_cloud_snow_particles
effective_radius_of_stratiform_cloud_graupel_particle -> effective_radius_of_stratiform_cloud_graupel_particles
effective_radius_of_stratiform_cloud_ice_particle -> effective_radius_of_stratiform_cloud_ice_particles
effective_radius_of_stratiform_cloud_rain_particle -> effective_radius_of_stratiform_cloud_rain_particles
effective_radius_of_stratiform_cloud_snow_particle -> effective_radius_of_stratiform_cloud_snow_particles

One could argue about the reference to ice, rain and snow "particles" which is probably not the most obvious terminology, but I suspect we chose to treat the names this way for consistency with the liquid water names. Unless anyone objects I will also add these aliases in the May update.

Interestingly, there is one cloud effective radius name that already says "particles", effective_radius_of_cloud_condensed_water_particles_at_cloud_top, so that will no longer be the odd one out!

As you say, we already use "particles" in the vast majority of aerosol names. I can find only four that use the singular:

It is natural to use "particle" if the names are written as above, but I think it can also be argued that the diameter names should be constructed following a similar pattern to the effective radius names, i.e. diameter_of_particles rather than "particle_diameter". If we take this approach, the names would become:
(This also makes clear that the electrical mobility name refers to aerosol particles).

If we make these changes, then I think we shouldn't alter the radiative effect names to say "particle".

I'm putting this forward as a possible alternative, but would also be fine with your approach to the aerosol names. I'd be interested to know what you think.

Best wishes,

Alison Pamment                                                         Tel: +44 1235 778065
NCAS/Centre for Environmental Data Analysis    Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory     
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.

-----Original Message-----
From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> On Behalf Of Martin Juckes - UKRI STFC
Sent: 24 April 2019 13:42
To: CF-metadata (cf-metadata at cgd.ucar.edu) <cf-metadata at cgd.ucar.edu>
Subject: [CF-metadata] Some standard name updates to improve consistency.

Hello All,

The standard name table has a high degree of internal consistency across thousands of variables, but there are a few anomalies. I'd like to suggest a few changes below.  These are minor issues,

 1. Change "aerosol" to "aerosol_particles".

The overwhelming majority of aerosol terms refer to "aerosol_particles". There are two anomalies:

  *   tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_expressed_as_sulfur_due_to_wet_deposition
  *   mercury_dry_aerosol

Should these be changed to "aerosol_particles"?

2. Primary production vs. primary productivity

There are 6 terms for net_primary_productivity_of_biomass_expressed_as_carbon..., and one for net_primary_production_of_biomass_expressed_as_carbon_per_unit_volume_in_sea_water. In addition, there are 6 terms using primary_production in the construction "due_to_net_primary_production".

Production and productivity are often used interchangeably, but some people draw a distinction. E.g. using "productivity" for a rate and "production" for an amount. The usage in the standard names could be interpreted as using "primary_production" in oceanic contexts and "primary_productivity" in land contexts, but net_primary_productivity_of_biomass_expressed_as_carbon is not explicitly defined as applying only to land. Should it be?

Can we either change these terms to consistently use "productivity" (or "production"), or, if that is not appropriate, provide some explanation of the use of two different terms for the same quantity?

3. aerodynamic_resistance

The definition of this term implies that it refers to the aerodynamic resistance of the boundary layer, rather than the more general concept of aerodynamic resistance as defined, for example, by AMS: http://glossary.ametsoc.org/wiki/Aerodynamic_resistance .

If the narrower term is intended, perhaps the name should be changed to aerodynamic_resistance_of_planetary_boundary_layer, so that it is clear that this is a boundary layer property.

4. Litter and Soil

To mean the combination of litter and soil, we have one use of "soil_and_litter", one of "litter_and_soil". There are multiple uses of "vegetation_litter_and_soil", so we can take this as the preferred order.

Can we change carbon_mass_flux_into_soil_and_litter_due_to_anthropogenic_land_use_or_land_cover_change to carbon_mass_flux_into_litter_and_soil_due_to_anthropogenic_land_use_or_land_cover_change for consistency?

5. Products

There are 7 terms which use the old name "omega", which is now aliassed to "lagrangian_tendency_of_air_pressure".  Two of these are redundant, because they are of the form "product_of_B_and_A" for terms already covered by "product_of_A_and_B".

 1. product_of_specific_humidity_and_omega
 2. product_of_omega_and_specific_humidity [redundant]  3. product_of_eastward_wind_and_omega
 4. product_of_northward_wind_and_omega
 5. product_of_air_temperature_and_omega
 6. product_of_omega_and_air_temperature [redundant]  7. product_of_geopotential_height_and_omega

Can we remove the two redundant terms, and replace "omega" with "lagrangian_tendency_of_air_pressure"?

6. Use of "net_downward" in aerosol indirect radiative effect terms

There are 5 aerosol direct radiative effect terms. These are analogous to cloud radiative effect terms (3)  and radiative forcing terms (12). For all the radiative forcing terms and the cloud radiative effect terms, the sign convention is assumed to be that positive forcing/radiative effect is equivalent to a downward radiative flux.  This is also true for the TOA direct radiative effect term. For 4 terms describing the aerosol direct radiative effect at the surface, there is an additional inclusion of "net_downward" in the term. This looks redundant to me, and I think it should be removed for consistency with other radiative effect and forcing terms.

* surface_net_downward_longwave_dust_ambient_aerosol_particles_direct_radiative_effect

* surface_net_downward_longwave_dust_ambient_aerosol_particles_direct_radiative_effect_assuming_clear_sky

* surface_net_downward_shortwave_dust_ambient_aerosol_particles_direct_radiative_effect

* surface_net_downward_shortwave_dust_ambient_aerosol_particles_direct_radiative_effect_assuming_clear_sky

7. Use of "downwelling" in attenuation coefficients

Attenuation of radiation is a measure of the reduction of strength of a radiation wave passing through a medium. It does not depend on the direction of travel of the radiation. One term includes redundant directional information:

  * volume_attenuation_coefficient_of_downwelling_radiative_flux_in_sea_water

This term is intended have some relevance to downwelling fluxes in sea water. Possibly it is intended to be evaluated at frequencies representative of the downwelling radiative flux.

 Can we remove "downwelling" from this term and/or clarify any assumptions about spectral range?

8. Specification of air vs. ocean

Scattering terms all specify whether they are in air or sea water, except one: backscattering_ratio. The definition makes it clear that this term is intended to refer to atmospheric backscattering. For consistency with other terms, it should be:

  *   backscattering_ratio_in_air

9. cloud liquid water particle vs. particles and aerosol particle vs. particles.

There are 2 terms referring to "cloud_liquid_water_particles" and 8 using the singular "cloud_liquid_water_particle". For aerosols, we have 236 referring to aerosol_particles and 2 referring to aerosol_particle.

One possible distinction is between adjectival use, as in "ambient_aerosol_particle_diameter", versus the more common substantive use, as in "asymmetry_factor_of_ambient_aerosol_particles".  If this approach is adopted, there are 5 aerosol particle direct radiative effect terms which should be changed to the singular adjectival form:

  *   surface_net_downward_longwave_dust_ambient_aerosol_particles_direct_radiative_effect
  *   surface_net_downward_longwave_dust_ambient_aerosol_particles_direct_radiative_effect_assuming_clear_sky
  *   surface_net_downward_shortwave_dust_ambient_aerosol_particles_direct_radiative_effect
  *   surface_net_downward_shortwave_dust_ambient_aerosol_particles_direct_radiative_effect_assuming_clear_sky
  *   toa_longwave_dust_ambient_aerosol_particles_direct_radiative_effect_assuming_clear_sky

The same argument would imply that all cloud liquid water particle terms should use the plural. There are two number concentration terms which already use the plural:


8 terms would need to be modified, 2 for number concentration and 6 for effective radius:

  *   effective_radius_of_cloud_liquid_water_particle
  *   effective_radius_of_cloud_liquid_water_particle_at_liquid_water_cloud_top
  *   effective_radius_of_convective_cloud_liquid_water_particle
  *   effective_radius_of_convective_cloud_liquid_water_particle_at_convective_liquid_water_cloud_top
  *   effective_radius_of_stratiform_cloud_liquid_water_particle
  *   effective_radius_of_stratiform_cloud_liquid_water_particle_at_stratiform_liquid_water_cloud_top
  *   number_concentration_of_convective_cloud_liquid_water_particle_at_convective_liquid_water_cloud_top
  *   number_concentration_of_stratiform_cloud_liquid_water_particle_at_stratiform_liquid_water_cloud_top


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