Dear Alison,

Thank you for reviewing all these. The "_clear_sky_and_no_aerosol" names look 
good.


6. & 7.

For the albedo terms: You are right about "spectral": this was included because 
the CMIP6 variables which need this standard name are requested in spectral 
frequency bands, but the term requested is an albedo, not an albedo per unit 
wave-number.


I believe that "spherical" and "hemispherical" have distinct meanings when 
applied to radiation terms. From ISO 9288-1996 ["Thermal insulation — Heat 
transfer by radiation .."]: "hemispherical" is used for quantities which "are 
related to all directions along which a surface element can emit or receive 
radiation", which I think applies here. Spherical irradiance refers to the 
total irradiance incident on a point from all angles. Hence, I think we should 
stay with hemispherical reflectance. On the other hand, "surface hemispherical 
reflectance" and "surface albedo" appear to mean the same thing, and we already 
have "surface_albedo", so it may be better to use that phrase here. I had not 
looked into this enough before, so thank you for querying the original 
suggestion.


The surface_albedo term makes no reference to the wavelength at which it should 
be calculated, but I believe that it is generally considered to be a quantity 
associated with shortwave radiation. Hence, I suggest we can drop this 
qualifier -- but only if everyone agrees that surface_albedo should, at least 
by default, apply to solar radiation.


Finally, "downwelling" is redundant here, since it is implicit in the 
definition of surface albedo. After these simplifying assumptions, we could use:
direct_surface_albedo
and
diffuse_surface_albedo.

8:
Yes, this the associated CMIP6 variable is the total incoming shortwave flux in 
bands, so a new name is not needed.

9 & 10
volume_extinction_coefficient_in_air_due_to_ambient_aerosol_particles and 
single_scattering_albedo_in_air_due_to_ambient_aerosol_particles: I agree.

11
aerasym: 
volume_spectral_asymmetry_factor_in_air_due_to_ambient_aerosol_particles
"asymmetry factor" and "backscatter fraction" appear to be two well defined 
terms. I'll check with Robert Pincus to see which one he wants.

Looking at this again, I'm concerned that the use of "due_to_" is not entirely 
correct here: both "asymmetry factor" and "backscatter fraction" are properties 
of the particles ... I don't think it is part of an additive collection of 
terms which the use of "due_to" appears to imply. Hence, accepting your 
comments about "volume" and "spectral", I suggest:
asymmetry_factor_of_ambient_aerosol_particles or 
backscatter_fraction_of_ambient_aerosol_particles

regards,
Martin

________________________________
Alison Pamment - UKRI STFCalison.pamment at stfc.ac.uk 
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Dear All,

Standard names were proposed some time ago for CMIP6 RFMIP and some of the 
names received a small amount of discussion back in 2016. However, none of the 
names were published at that time. Three names were proposed for GeoMIP as long 
ago as 2015, but strangely, although I have a copy of the GeoMIP email (which 
was addressed to the mailing list) it seems never to have actually appeared on 
the list. The RFMIP and GeoMIP quantities are similar, so I will address both 
in this message. I would particularly like some advice on RFMIP proposals 6 - 
11.

GeoMIP

1. stratosphere_optical_thickness_due_to_ambient_aerosol_particles (1)
The same quantity was recently proposed for PMIP and added in Version 53 of the 
standard name table, so this one is done.

2. toa_outgoing_shortwave_flux_assuming_clear_sky_and_no_aerosol (Wm-2)
This is the same as RFMIP proposal 1 (see below), so I will deal with this one 
as part of the RFMIP request.

3. toa_outgoing_shortwave_flux_assuming_no_aerosol (W m-2)
This proposal is straight forward. We have one existing assuming_no_aerosol 
name, 
volume_attenuated_backwards_scattering_function_in_air_assuming_no_aerosol_or_cloud.
 The definition can be constructed from existing text:
'The abbreviation "toa" means top of atmosphere. The term "shortwave" means 
shortwave radiation. The TOA outgoing shortwave flux is the reflected and 
scattered solar radiative flux i.e. the "upwelling" TOA shortwave flux, 
sometimes called the "outgoing shortwave radiation" or "OSR". In accordance 
with common usage in geophysical disciplines, "flux" implies per unit area, 
called "flux density" in physics. A phrase "assuming_condition" indicates that 
the named quantity is the value which would obtain if all aspects of the system 
were unaltered except for the assumption of the circumstances specified by the 
condition.'

This name is accepted for publication in the standard name table and has been 
included in this week's update.

RFMIP

1. toa_outgoing_shortwave_flux_assuming_clean_clear_sky (W m-2)
Jonathan commented (in 2016) that it would be preferable to say 'no_aerosol' 
rather than 'clean' 
(http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2016/059135.html). I have 
seen some offlist emails that indicate 'no_aerosol' is now being used in 
preference to 'clean' in the CMIP6 long names. Also, this is consistent with 
the one existing no_aerosol name and the GeoMIP proposals.

This one should therefore be as follows:
toa_outgoing_shortwave_flux_assuming_clear_sky_and_no_aerosol (W m-2)
'The abbreviation "toa" means top of atmosphere. The term "shortwave" means 
shortwave radiation. The TOA outgoing shortwave flux is the reflected and 
scattered solar radiative flux i.e. the "upwelling" TOA shortwave flux, 
sometimes called the "outgoing shortwave radiation" or "OSR". In accordance 
with common usage in geophysical disciplines, "flux" implies per unit area, 
called "flux density" in physics. A phrase "assuming_condition" indicates that 
the named quantity is the value which would obtain if all aspects of the system 
were unaltered except for the assumption of the circumstances specified by the 
condition. "Clear sky" means in the absence of clouds.'

This name, units and definition are consistent with existing names so it is 
accepted and has been added in this week's standard name table update.

This proposal has been around for a long time and there is a possibility that 
some data have been written with the original version of the name. For this 
reason I have added toa_outgoing_shortwave_flux_assuming_clean_clear_sky to the 
standard name table and then immediately turned it into an alias of 
toa_outgoing_shortwave_flux_assuming_clear_sky_and_no_aerosol. This has been 
achieved by updating the standard name table twice - both versions will be 
published this week. (The double update is necessary to keep in sync with the 
standard name publication process on the NERC Vocabulary Server). We don't 
usually publish two versions of a name almost simultaneously, but there is a 
precedent for treating long standing proposals in this way - for example it was 
done for some standard names arising from trac ticket 37 which took a couple of 
years to agree. This arrangement affects 5 names for RFMIP.

2. surface_downwelling_shortwave_flux_in_air_assuming_clean_clear_sky (W m-2)

As for proposal 1, we should replace 'clean' with 'no_aerosol':
surface_downwelling_shortwave_flux_in_air_assuming_clear_sky_and_no_aerosol (W 
m-2)
'The surface called "surface" means the lower boundary of the atmosphere. 
Downwelling radiation is radiation from above. It does not mean "net downward". 
The term "shortwave" means shortwave radiation. Surface downwelling shortwave 
is the sum of direct and diffuse solar radiation incident on the surface, and 
is sometimes called "global radiation". When thought of as being incident on a 
surface, a radiative flux is sometimes called "irradiance". In addition, it is 
identical with the quantity measured by a cosine-collector light-meter and 
sometimes called "vector irradiance". In accordance with common usage in 
geophysical disciplines, "flux" implies per unit area, called "flux density" in 
physics. A phrase "assuming_condition" indicates that the named quantity is the 
value which would obtain if all aspects of the system were unaltered except for 
the assumption of the circumstances specified by the condition. "Clear sky" 
means in the absence of clouds.'

This name, units and definition are consistent with existing names so it is 
accepted and will be added in this week's standard name table update. As for 
proposal 1, I have published the original version of the name and immediately 
turned it into an alias of the final version.

3. surface_upwelling_shortwave_flux_in_air_assuming_clean_clear_sky (W m-2)

As for proposal 1, we should replace 'clean' with 'no_aerosol':
surface_upwelling_shortwave_flux_in_air_assuming_clear_sky_and_no_aerosol (W 
m-2)
'The surface called "surface" means the lower boundary of the atmosphere. 
Upwelling radiation is radiation from below. It does not mean "net upward". The 
term "shortwave" means shortwave radiation. When thought of as being incident 
on a surface, a radiative flux is sometimes called "irradiance". In addition, 
it is identical with the quantity measured by a cosine-collector light-meter 
and sometimes called "vector irradiance". In accordance with common usage in 
geophysical disciplines, "flux" implies per unit area, called "flux density" in 
physics. A phrase "assuming_condition" indicates that the named quantity is the 
value which would obtain if all aspects of the system were unaltered except for 
the assumption of the circumstances specified by the condition. "Clear sky" 
means in the absence of clouds.'

This name, units and definition are consistent with existing names so it is 
accepted and will be added in this week's standard name table update. As for 
proposal 1, I have published the original version of the name and immediately 
turned it into an alias of the final version.

4. upwelling_shortwave_flux_in_air_assuming_clean_clear_sky (W m-2)

As for proposal 1, we should replace 'clean' with 'no_aerosol':
upwelling_shortwave_flux_in_air_assuming_clear_sky_and_no_aerosol (W m-2)
'Upwelling radiation is radiation from below. It does not mean "net upward". 
The term "shortwave" means shortwave radiation. When thought of as being 
incident on a surface, a radiative flux is sometimes called "irradiance". In 
addition, it is identical with the quantity measured by a cosine-collector 
light-meter and sometimes called "vector irradiance". In accordance with common 
usage in geophysical disciplines, "flux" implies per unit area, called "flux 
density" in physics. A phrase "assuming_condition" indicates that the named 
quantity is the value which would obtain if all aspects of the system were 
unaltered except for the assumption of the circumstances specified by the 
condition. "Clear sky" means in the absence of clouds.'

This name, units and definition are consistent with existing names so it is 
accepted and will be added in this week's standard name table update. As for 
proposal 1, I have published the original version of the name and immediately 
turned it into an alias of the final version.

5. downwelling_shortwave_flux_in_air_assuming_clean_clear_sky (W m-2)

As for proposal 1, we should replace 'clean' with 'no_aerosol':
downwelling_shortwave_flux_in_air_assuming_clear_sky_and_no_aerosol (W m-2)
'Downwelling radiation is radiation from above. It does not mean "net 
downward". The term "shortwave" means shortwave radiation. When thought of as 
being incident on a surface, a radiative flux is sometimes called "irradiance". 
In addition, it is identical with the quantity measured by a cosine-collector 
light-meter and sometimes called "vector irradiance". In accordance with common 
usage in geophysical disciplines, "flux" implies per unit area, called "flux 
density" in physics. A phrase "assuming_condition" indicates that the named 
quantity is the value which would obtain if all aspects of the system were 
unaltered except for the assumption of the circumstances specified by the 
condition. "Clear sky" means in the absence of clouds.'

This name, units and definition are consistent with existing names so it is 
accepted and will be added in this week's standard name table update. As for 
proposal 1, I have published the original version of the name and immediately 
turned it into an alias of the final version.

Now I am coming to some even older proposals for RFMIP, dating from 2015. They 
received only one comment at the time and I think the names, units and 
definitions need some work. For two of the quantities I think we can probably 
use existing names. I hope Martin, Daniel and Robert will be able to advise on 
these proposals.

6. CMIP6 short name albdiff.
surface_spectral_hemispherical_reflectance_of_diffuse_shortwave_radiation (1)
I think we probably shouldn't say 'spectral' in the name. We used to have 
standard names that included 'spectral' but then we agreed to change them all 
to say 'per_unit_wavelength' or 'per_unit_wavenumber'. Per_unit_wavelength 
introduces a unit of m-1 and per_unit_wavenumber introduces a unit of (m-1)-1; 
I suspect neither is appropriate in this case. We can still add a sentence in 
the definition that would say something like 'The reflectance is assumed to be 
an integral over all wavelengths, unless a coordinate of radiation_wavelength 
or radiation_frequency is included to specify either the wavelength or 
frequency' to allow the quantity to be specified at different wavelengths or 
frequencies. We do this for quite a number of existing names.

We have an existing name downwelling_spherical_irradiance_in_sea_water defined 
as 'Downwelling radiation is radiation from above. It does not mean "net 
downward". Spherical irradiance is the radiation incident on unit area of a 
hemispherical (or "2-pi") collector. It is sometimes called "scalar 
irradiance". The direction (up/downwelling) is specified. Radiation incident on 
a 4-pi collector has standard names of "omnidirectional spherical irradiance".' 
This makes me think that we should refer to the proposed name as a 'spherical' 
rather than 'hemishpherical' reflectance - presumably it is the reflectance 
that would apply to any shortwave radiation arriving at the surface from any 
upward direction. Apart from the omnidirectional names, all the existing 
'spherical' names include some sense of direction (upwelling or downwelling). 
Since the current proposal is for shortwave radiation incident at the surface, 
I suggest we need to say 'downwelling'.

We do have existing names for diffuse radiation, e.g. 
surface_diffuse_downwelling_shortwave_flux_in_air. We can just say 'shortwave' 
instead of 'shortwave radiation' because that would be explained in the 
definition.

Putting all this together, I think we would arrive at the following name, units 
and definition:
surface_diffuse_downwelling_shortwave_spherical_reflectance (1)
'The surface called "surface" means the lower boundary of the atmosphere. 
"Diffuse" radiation is radiation that has been scattered by particles in the 
atmosphere such as cloud droplets and aerosols. Downwelling radiation is 
radiation from above. It does not mean "net downward". The term "shortwave" 
means shortwave radiation. Spherical reflectance is the reflectance of 
radiation incident on unit area of a hemispherical (or "2-pi") collector. 
Reflectance is the ratio of the energy of the reflected to the incident 
radiation. A coordinate variable of radiation_wavelength or radiation_frequency 
can be used to specify the wavelength or frequency, respectively, of the 
radiation.'

What do others think?

7. CMIP6 short name albdir.
surface_spectral_hemispherical_reflectance_of_direct_shortwave_radiation (1)

We have one existing name for direct radiation, 
direct_downwelling_shortwave_flux_in_air.

Following similar arguments to proposal 6, I suggest this one should be:
surface_direct_downwelling_shortwave_spherical_reflectance (1)
'The surface called "surface" means the lower boundary of the atmosphere. 
"Direct" (also known as "beam") radiation is radiation that has followed a 
direct path from the sun and is alternatively known as "direct insolation". 
Downwelling radiation is radiation from above. It does not mean "net downward". 
The term "shortwave" means shortwave radiation. Spherical reflectance is the 
reflectance of radiation incident on unit area of a hemispherical (or "2-pi") 
collector. Reflectance is the ratio of the energy of the reflected to the 
incident radiation. A coordinate variable of radiation_wavelength or 
radiation_frequency can be used to specify the wavelength or frequency, 
respectively, of the radiation.'

Do others agree?

8. CMIP6 short name sol.
toa_incoming_shortwave_flux_per_unit_wavelength (W m-2)
If this is intended to be a truly spectrally resolved quantity, then the name 
is correct, but as I mentioned for proposal 6 the units should be W m-2 m-1. We 
do have an existing name toa_incoming_shortwave_flux which is integrated across 
all shortwave frequencies.

If we leave the name as it is, then we would have:
toa_incoming_shortwave_flux_per_unit_wavelength (W m-2 m-1)
'The abbreviation "toa" means top of atmosphere. The term "shortwave" means 
shortwave radiation. The TOA incoming shortwave flux is the radiative flux from 
the sun i.e. the "downwelling" TOA shortwave flux. In accordance with common 
usage in geophysical disciplines, "flux" implies per unit area, called "flux 
density" in physics. A coordinate variable for radiation wavelength should be 
given the standard name radiation_wavelength.'

If these units are not acceptable we could use the existing name
toa_incoming_shortwave_flux (W m-2)
'The abbreviation "toa" means top of atmosphere. The term "shortwave" means 
shortwave radiation. The TOA incoming shortwave flux is the radiative flux from 
the sun i.e. the "downwelling" TOA shortwave flux. In accordance with common 
usage in geophysical disciplines, "flux" implies per unit area, called "flux 
density" in physics.'

The definition is the same except for the sentence about the coordinate 
variable. We could add a slightly softer version of that sentence, similar to 
the reflectance names, 'A coordinate variable of radiation_wavelength or 
radiation_frequency can be used to specify the wavelength or frequency, 
respectively, of the radiation.' This would allow wavelength to be used as a  
dimension, but wouldn't alter the units.

What do others think?

9. CMIP6 short name aerext.
volume_spectral_extinction_coefficient_in_air_due_to_ambient_aerosol_particles 
(1)

As with the reflectance proposals, we shouldn't say 'spectral' in the name and 
if we say 'per_unit_wavelength' it would alter the units. In fact, for this 
quantity I think we have an existing name that would do the job:
volume_extinction_coefficient_in_air_due_to_ambient_aerosol_particles (1)
'The volume extinction coefficient is the fractional change of radiative flux 
per unit path length. Extinction is the sum of absorption and scattering, 
sometimes called "attenuation". "Extinction" is the term most commonly used at 
optical wavelengths whereas "attenuation" is more often used at radio and radar 
wavelengths. "Aerosol" means the system of suspended liquid or solid particles 
in air (except cloud droplets) and their carrier gas, the air itself. 
"Ambient_aerosol" means that the aerosol is measured or modelled at the ambient 
state of pressure, temperature and relative humidity that exists in its 
immediate environment. "Ambient aerosol particles" are aerosol particles that 
have taken up ambient water through hygroscopic growth. The extent of 
hygroscopic growth depends on the relative humidity and the composition of the 
particles. 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.'

Again, we could add an advisory sentence to the definition to say that a 
coordinate variable of radiation_wavelength can be specified. What do others 
think?

10. CMIP6 short name aerssa.
volume_spectral_single_scattering_albedo_in_air_due_to_ambient_aerosol_particles
 (1)

This one is similar to proposal 9. Again we shouldn't say 'spectral' and there 
is the question of units. I think this is another one for which we have an 
existing name:
single_scattering_albedo_in_air_due_to_ambient_aerosol_particles (1)
'"Single scattering albedo" is the fraction of radiation in an incident light 
beam scattered by the particles of an aerosol reference volume for a given 
wavelength. It is the ratio of the scattering and the extinction coefficients 
of the aerosol particles in the reference volume. A coordinate variable with a 
standard name of radiation_wavelength or radiation_frequency should be included 
to specify either the wavelength or frequency. "Aerosol" means the system of 
suspended liquid or solid particles in air (except cloud droplets) and their 
carrier gas, the air itself. "Ambient_aerosol" means that the aerosol is 
measured or modelled at the ambient state of pressure, temperature and relative 
humidity that exists in its immediate environment. "Ambient aerosol particles" 
are aerosol particles that have taken up ambient water through hygroscopic 
growth. The extent of hygroscopic growth depends on the relative humidity and 
the composition of the particles. To specify the relative humidity and 
temperature at which the quantity described by the standard name applies, 
provide scalar coordinate variables with standard names of "relative_humidity" 
and "air_temperature". 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.'

As with proposal 9, we could add an advisory sentence to the definition to say 
that a coordinate variable of radiation_wavelength can be specified. What do 
others think?

11. CMIP6 short name aerasym.
volume_spectral_asymmetry_factor_in_air_due_to_ambient_aerosol_particles (1)

I am not really familiar with this quantity, but I note Markus Fiebig's comment 
(http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2015/058422.html) when the 
names were originally proposed to the mailing list:
> For the aerosol asymmetry factor / parameter, I'm familiar with the 
> definition as the cosine weighted angular integral of the aerosol scattering
> phase function. For the property you describe, I know the term "backscatter 
> fraction", i.e. the ratio of the integral over the scattering phase
> function in the backward hemisphere (backscatter coefficient) over the 
> aerosol scattering coefficient.

It sounds like this one is a new quantity to standard names. Again, I don't 
think the name itself should say 'spectral'.  Rather than 'factor' I would 
suggest the term 'coefficient' which is already used in existing names. Also, I 
don't know whether we really need 'volume' in this case - I think this refers 
to extinction along the path of the radiation and volume coefficients have 
units of m-1. Does the asymmetry factor refer to a single scattering event or 
to multiple events along a path? I suggest the name would be:
[volume_]asymmetry_coefficient_of_radiative_flux_in_air_due_to_ambient_aerosol_particles
 (1)
and the definition would be something like:
'The asymmetry coefficient is the ratio of forward to backward scattered 
radiative flux. The asymmetry coefficient is assumed to be an integral over all 
wavelengths, unless a coordinate of radiation_wavelength is included to specify 
the wavelength. 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. "Aerosol" 
means the system of suspended liquid or solid particles in air (except cloud 
droplets) and their carrier gas, the air itself. "Ambient_aerosol" means that 
the aerosol is measured or modelled at the ambient state of pressure, 
temperature and relative humidity that exists in its immediate environment. 
"Ambient aerosol particles" are aerosol particles that have taken up ambient 
water through hygroscopic growth. The extent of hygroscopic growth depends on 
the relative humidity and the composition of the particles. To specify the 
relative humidity and temperature at which the quantity described by the 
standard name applies, provide scalar coordinate variables with standard names 
of "relative_humidity" and "air_temperature".'

What do others think?

Best wishes,
Alison

------
Alison Pamment                                 Tel: +44 1235 778065
NCAS/Centre for Environmental Data Archival    Email: alison.pamment at 
stfc.ac.uk<http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata>
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.



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