[CF-metadata] VolMIP Data Request: CF Standard Names

From: Alison Pamment - UKRI STFC <alison.pamment>
Date: Mon, 14 May 2018 13:59:33 +0000

Dear Martin,

Thank you for making these proposals for VolMIP names and for providing a definition to explain the difference between volcanic ash and volcanic aerosol. As you point out in the proposals, these names are analogous to existing ones and to some that have been proposed for PMIP - they seem to be quite straight forward quantities. In some places longwave and shortwave appear to have been accidentally transposed, and there are a few mistakes in the units (probably just typos rather than mistakes in the CMIP6 data request). I have taken the liberty of correcting these as I think it's very clear in all cases what was actually intended. The definitions are all based on existing text. I don't think there are any other outstanding issues with these names, so they are accepted for inclusion in the standard name table. Please see below for the details of the individual names.

> The new names are all associated with volcanic aerosols in the atmosphere ... following existing patterns of usage we refer to them as
> "volcanic_ambient_aerosol_particles" (cf. "dust_ambient_aerosol_particles").

This seems like a sensible syntax to adopt for these names.

> There are 3 names referring to volcanic ash in air: in order to make the distinction clear we need a short piece of help text: "Volcanic aerosols
> include both volcanic ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions."
>
> 1. CMIP6 short name od550volso4: Aerosol optical depth at 550 nm due to stratospheric volcanic aerosols
>
> Proposed name:
> stratosphere_optical_thickness_due_to_volcanic_ambient_aerosol_particles (W m-2)
>
> This name is analogous to the existing standard name atmosphere_optical_thickness_due_to_ambient_aerosol_particles.

The name looks fine. The units for an optical thickness should be '1', i.e. dimensionless - I assume this was just an oversight. I have constructed a definition from existing text:
'The optical thickness is the integral along the path of radiation of a volume scattering/absorption/attenuation coefficient. The radiative flux is reduced by a factor exp(-"optical_thickness") on traversing the path. A coordinate variable of radiation_wavelength or radiation_frequency can be specified to indicate that the optical thickness applies at specific wavelengths or frequencies. The stratosphere optical thickness applies to radiation passing through the atmosphere layer between the tropopause and stratopause. 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". Volcanic aerosols include both volcanic ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions.'

This name is accepted for publication in the standard name table and will be added in the May update.

> 2. CMIP6 short name lwsffluxaero: Longwave flux due to volcanic aerosols at the surface
>
> Proposed name:
> surface_downwelling_longwave_flux_in_air_due_to_volcanic_ambient_aerosol_particles (W m-2)
>
> As surface_downwelling_longwave_flux_in_air, but only component attributed to volcanic aerosols. (cf. existing CMIP variable rlds).

The name and units look fine. I have constructed a definition from existing text:
'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 "longwave" means longwave 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. 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 relativ
e 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". Volcanic aerosols include both volcanic ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions.'

This name is accepted for publication in the standard name table and will be added in the May update.


> 3. CMIP6 short name lwtoafluxaerocs: Longwave flux due to volcanic aerosols at TOA under clear sky
>
> Proposed name:
> toa_outgoing_longwave_flux_due_to_volcanic_ambient_aerosol_particles_assuming_clear_sky (W m-2)

The name and units look fine. I have constructed a definition from existing text:
' "toa" means top of atmosphere. The term "longwave" means longwave radiation. The TOA outgoing longwave flux is the upwelling thermal radiative flux, often called the "outgoing longwave radiation" or "OLR". In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics. 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 h
umidity 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". Volcanic aerosols include both volcanic ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions. 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 will be added in the May update.

> 4. CMIP6 short name swsffluxaero: Shortwave heating rate due to volcanic aerosols
>
> Proposed name:
> surface_downwelling_longwave_flux_in_air_due_to_volcanic_ambient_aerosol_particles (W m-2)
>
> Analogous to lwsffluxaero above

The CMIP short name and description clearly indicate that this is a shortwave quantity - I assume that the proposed name was copied and pasted from proposal 2 and that it should actually be:
surface_downwelling_shortwave_flux_in_air_due_to_volcanic_ambient_aerosol_particles (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. 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. 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 rela
tive 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". Volcanic aerosols include both volcanic ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions.'

The name, units and definition as shown here are accepted for publication in the standard name table and will be added in the May update.

> 5. CMIP6 short name swtoafluxaerocs: Shortwave flux due to volcanic aerosols at TOA under clear sky
>
> Proposed name:
> toa_outgoing_shortwave_flux_due_to_volcanic_ambient_aerosol_particles_assuming_clear_sky (W m-2)

The name and units look fine. I have constructed a definition 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. 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 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 w
hich the quantity described by the standard name applies, provide scalar coordinate variables with standard names of "relative_humidity" and "air_temperature". Volcanic aerosols include both volcanic ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions. 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 will be added in the May update.

> 6. zmlwaero: Zonal mean longwave heating rate due to volcanic aerosols
>
> Proposed name:
> tendency_of_air_temperature_due_to_shortwave_heating_from_volcanic_ambient_aerosol_particles (W m-2)
>
> Comparable to tendency_of_air_temperature_due_to_shortwave_heating_assuming_clear_sky

The CMIP short name and description clearly indicate that this is a longwave quantity. The units of a temperature tendency should be K s-1. I assume that the proposed name should actually be:
tendency_of_air_temperature_due_to_longwave_heating_from_volcanic_ambient_aerosol_particles (K s-1)
'The phrase "tendency_of_X" means derivative of X with respect to time. Air temperature is the bulk temperature of the air, not the surface (skin) 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. The term "longwave" means longwave radiation. "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". Volcanic aerosols include both volcanic ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions.

The name, units and definition as shown here are accepted for publication in the standard name table and will be added in the May update.

> 7. CMIP6 short name zmswaero: Zonal mean shortwave heating rate due to volcanic aerosols
>
> Proposed name:
> tendency_of_air_temperature_due_to_longwave_heating_from_volcanic_ambient_aerosol_particles (W m-2)
>
> As for zmlwaero

The CMIP short name and description clearly indicate that this is a shortwave quantity. The units of a temperature tendency should be K s-1. I assume that the proposed name should actually be:
tendency_of_air_temperature_due_to_shortwave_heating_from_volcanic_ambient_aerosol_particles (K s-1)
'The phrase "tendency_of_X" means derivative of X with respect to time. Air temperature is the bulk temperature of the air, not the surface (skin) 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. The term "shortwave" means shortwave radiation. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "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". Volcanic aerosols include both volcanic
ash and secondary products such as sulphate aerosols formed from gaseous emissions of volcanic eruptions.'

This completes the list of standard names needed for VolMIP.

Best wishes,
Alison

------
Alison Pamment Tel: +44 1235 778065
NCAS/Centre for Environmental Data Archival Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
Received on Mon May 14 2018 - 07:59:33 BST