Dear Markus and Jonathan,
In tandem with reviewing Brigitte Koffi-Lefeivre's aerosol name proposals, I have reviewed this set of proposals (see
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/056946.html and following posts) as there were a number of overlapping issues in the discussions. Markus has worked on these proposals over a long period and been through several iterations of the names, so I would like to try and include as many of them is possible in the next update of the standard name table. A number of the proposals can now be accepted for publication. Others remain under discussion, although many of them could also be accepted if we can reach agreement over the next few days, particularly on the use of the term "surface".
I would like to publish an update to the standard name table within the next week, concentrating on aerosol names. I will then begin preparation of another update which will focus mainly on remote sensing names, but will also include some other, smaller sets of proposals that have been agreed recently.
a. Summary of status of "aerosol optical properties" proposals
5 of the 20 proposals have been accepted for publication in the standard name table. The other 15 remain under discussion. Detailed comments on the individual names are given below. The proposals can also be viewed in the CF names editor at:
http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=&proposerfilter=Markus&descfilter=&unitfilter=&yearfilter=&filter+and+display=Filter. Names with an amber title bar are accepted for publication and will appear in the next version of the standard name table. Names with a title bar that appears greenish/brownish (depending on your display screen) are still under discussion. Below the title bar of each name and at the right of the screen you will also see a coloured label which indicates whether the proposal relates to a new name, creation of an alias (term change), or an updated definition.
During the discussions of Markus' and Brigitte's names, we reached a general consensus on using "aerosol particle" rather than simply "aerosol". All 138 existing aerosol names have been reviewed and aliases created to change "aerosol" to "aerosol_particles" in the vast majority of cases. In addition, the definition of all aerosol names has been corrected to reflect the "text book" definition as supplied by Markus. The text now reads " "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself." Brigitte also amended her proposals to be consistent with this approach.
Consensus has been reached on the use of the terms ambient/dry/dried to describe the state of the aerosol particles in relation to the relative humidity and their water content. I have updated the definitions of 42 existing ambient aerosol names to match the expanded wording agreed in this discussion.
The discussion appeared to be approaching consensus on dropping the term "surface" for those names that contain it because it was stated that the measurements are actually taken at a height of 4-5 m. However, I am not sure whether the point was fully agreed. If we can establish whether it is OK to drop "surface" then there are 6 more names that can be accepted straight away and included in the impending standard name table update. In all, proposals 2 and 6 - 18 are affected by this point.
Some discussion is still needed around the use of "spherical_backscattering". My detailed comments are given in the discussion of proposal (5) below. This issue also affects proposal 12.
I have also given individual comments on four number_concentration and size_distribution names.
b. Coordinate variables
Two new coordinate variable names have been proposed (numbered 19 and 20 in the original list). I would like to deal with these first as they underlie the definitions of the many of the other names.
19. Proposed: electrical_mobility_particle_diameter (canonical units of m).
"The diameter of an aerosol particle as selected by its electrical mobility."
Consensus was reached on this proposal as it stands.
Status: this name is accepted for publication in the standard name table.
20. Proposed: sizing_relative_humidity
Consensus reached: relative_humidity_for_aerosol_particle_size_selection (canonical units of "1").
"Relative humidity at which the size of a sampled aerosol particle was selected. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself."
Status: this name is accepted for publication in the standard name table.
c. The remaining proposals and their current status are listed in full below.
1. Proposed: volume_scattering_coefficient_in_air_due_to_ambient_aerosol (m-1)
We need to add "particles" for consistency with the new "aerosol" definition and Brigitte's proposals. I have also made small modifications to the definition text for consistency with other "ambient aerosol" and "volume_scattering_coefficient" names.
Final version of name: volume_scattering_coefficient_in_air_due_to_ambient_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". "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 exist 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". A coor
dinate variable of radiation_wavelength or radiation_frequency can be specified to indicate that the property applies at specific wavelengths or frequencies. 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."
Status: this name is accepted for publication in the standard name table.
2. Proposed: surface_volume_scattering_coefficient_in_air_due_to_ambient_aerosol (m-1)
With the addition of the word "particles" and if the "surface" qualifier is no longer needed, then this name would be the same as (1). Do we still need a separate "surface" name?
Status: still under discussion.
3. Proposed: volume_scattering_coefficient_in_air_due_to_dried_aerosol (m-1)
We need to add "particles" for consistency with the new "aerosol" definition and Brigitte's proposals. I have also made small modifications to the definition text for consistency with other "volume_scattering_coefficient" names and the newly agreed coordinate variable names.
Final version of name: volume_scattering_coefficient_in_air_due_to_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state before sizing, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the sample was sized, provide a scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. The specification of a physical process by the p
hrase "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."
Status: this name is accepted for publication in the standard name table.
4. Proposed: volume_absorption_coefficient_in_air_due_to_dried_aerosol (m-1)
We need to add "particles" for consistency with the new "aerosol" definition and Brigitte's proposals. I have also made small modifications to the definition text for consistency with other "volume_scattering_coefficient" names and the newly agreed coordinate variable names.
Final version of name: volume_absorption_coefficient_in_air_due_to_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state before sizing, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the sample was sized, provide a scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. The specification of a physical process by the p
hrase "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."
Status: this name is accepted for publication in the standard name table.
5. volume_spherical_backscattering_coefficient_in_air_due_to_dried_aerosol (m-1)
We need to add "particles" for consistency with the new "aerosol" definition and Brigitte's proposals. I have also made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"?
My next comments relate to "spherical_backscattering". I'm afraid it's necessary to pick this apart very carefully, so as to explain my reasoning!
i. Backscattering
There was a recent discussion on the mailing list regarding some radar backscattering names (see
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2014/057565.html and following posts). We discussed possible definitions of backscattering/backwards_scattering both of which are currently in use in standard names. Although the point has not yet been decided conclusively, I think we were moving towards standardizing on the term "backwards_scattering" for names where a specific rearward scattering angle is not supplied. Therefore, for your purposes I think this is the term we should use.
ii. Spherical
In a discussion of an earlier iteration of these proposals there was some debate about the use of "(hemi)spherical scattering" and what is meant by this. In particular, there was a discussion of units and whether it is necessary even to use "spherical" in this name. Certainly the term is used to describe radiation travelling along a range of directions contained within a 2-pi solid angle. However, a search of the standard name table shows that it has been used only in the context of "spherical irradiance" defined as "spherical irradiance is the radiation incident on unit area of a hemispherical (or "2-pi") collector." Units of these quantities all contain m-2 to take account of the "per unit area" and so I do not think that these quantities are integrated over the whole hemisphere: I think instead that one would integrate the spherical quantity to calculate the radiation flux arriving at a single point from all directions on the hemisphere. I hope someone more familiar with these quantities will correct me i
f I am wrong!
For the current proposal, I believe the intention is to quantify the attenuation of the incident beam caused by scattering into any backwards angle, and not to concern ourselves with what happens subsequently to the scattered radiation. Is that correct? If so, then I think we need something very similar to the existing name volume_backwards_scattering_coefficient_of_radiative_flux_in_sea_water in which "backwards_scattering" is defined as follows: "Backwards scattering refers to the sum of scattering into all backward angles i.e. scattering_angle exceeding pi/2 radians. A scattering_angle should not be specified with this quantity." I think the "sum of scattering into all backward angles" means exactly the same as "the coefficient is integrated over the rearward hemisphere" which Markus specified in the proposal.
Latest version of name: volume_backwards_scattering_coefficient_in_air_due_to_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with specific_ instead of volume_. Backwards scattering refers to the sum of scattering into all backward angles i.e. scattering_angle exceeds pi/2 radians. A scattering_angle should not be specified with this quantity. The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths, unless a coordinate of radiation_wavelength is included to specify the wavelength. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the property applies, provide a scalar coordinate variable with the standard name of "relative_humidity". The specification of a physical process by the phrase "due_to_" process means t
hat the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase."
Is this OK?
Status: still under discussion
6. surface_volume_scattering_coefficient_at_stp_in_air_due_to_pm1_dried_aerosol (m-1)
As with the other proposals, we need to add "particles" to the name for consistency. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? If so, this name can be accepted for publication.
Latest version of name: volume_scattering_coefficient_at_stp_in_air_due_to_pm1_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity described by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm1" refers to the fraction of aerosol particles with an aerodynam
ic diameter of less than or equal to 1 micrometer, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide a scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa)."
Is this OK?
Status: still under discussion
7. surface_volume_scattering_coefficient_at_stp_in_air_due_to_pm2p5_dried_aerosol (m-1)
As with the other proposals, we need to add "particles" to the name for consistency. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? If so, this name can be accepted for publication.
Latest version of name: volume_scattering_coefficient_at_stp_in_air_due_to_pm2p5_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1, i.e. multiplied by density, have standard names with "specific_" instead of "volume_". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity described by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm2p5" refers to the fraction of aerosol particles with an aerod
ynamic diameter of less than or equal to 2.5 micrometers, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa)."
Is this OK?
Status: still under discussion
8. surface_volume_scattering_coefficient_at_stp_in_air_due_to_pm10_dried_aerosol (m-1)
As with the other proposals, we need to add "particles" to the name for consistency. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? If so, this name can be accepted for publication.
Latest version of name: volume_scattering_coefficient_at_stp_in_air_due_to_pm10_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1, i.e. multiplied by density, have standard names with "specific_" instead of "volume_". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity described by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm10" refers to the fraction of aerosol particles with an aerody
namic diameter of less than or equal to 10 micrometers, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa). "surface" means that the property applies at the lower boundary of the atmosphere."
Is this OK?
Status: still under discussion
9. surface_volume_absorption_coefficient_at_stp_in_air_due_to_pm1_dried_aerosol (m-1)
As with the other proposals, we need to add "particles" to the name for consistency. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? If so, this name can be accepted for publication.
Latest version of name: volume_absorption_coefficient_at_stp_in_air_due_to_pm1_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity described by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm1" refers to the fraction of aerosol particles with an aerodynam
ic diameter of less than or equal to 1 micrometer, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa)."
Is this OK?
Status: still under discussion
10. surface_volume_absorption_coefficient_at_stp_in_air_due_to_pm2p5_dried_aerosol (m-1)
As with the other proposals, we need to add "particles" to the name for consistency. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? If so, this name can be accepted for publication.
Latest version of name: volume_absorption_coefficient_at_stp_in_air_due_to_pm2p5_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity described by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm2p5" refers to the fraction of aerosol particles with an aerodyn
amic diameter of less than or equal to 2.5 micrometers, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa)."
Is this OK?
Status: still under discussion
11. surface_volume_absorption_coefficient_at_stp_in_air_due_to_pm10_dried_aerosol (m-1)
As with the other proposals, we need to add "particles" to the name for consistency. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? If so, this name can be accepted for publication.
Latest version of name: volume_absorption_coefficient_at_stp_in_air_due_to_pm10_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity described by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm10" refers to the fraction of aerosol particles with an aerodyna
mic diameter of less than or equal to 10 micrometers, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa). "surface" means that the property applies at the lower boundary of the atmosphere."
Is this OK?
Status: still under discussion
12. surface_volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_pm1_dried_aerosol (m-1)
We need to add "particles" for consistency with the new "aerosol" definition and Brigitte's proposals. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? My comments relating to "spherical_backscattering" are the same as for proposal 5.
Latest version of name: volume_backwards_scattering_coefficient_at_stp_in_air_due_to_pm1_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". Backwards scattering refers to the sum of scattering into all backward angles i.e. scattering_angle exceeds pi/2 radians. A scattering_angle should not be specified with this quantity. The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity descri
bed by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm1" refers to the fraction of aerosol particles with an aerodynamic diameter of less than or equal to 1 micrometer, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa)."
Is this OK?
Status: still under discussion
13. surface_volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_pm2p5_dried_aerosol (m-1)
We need to add "particles" for consistency with the new "aerosol" definition and Brigitte's proposals. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? My comments relating to "spherical_backscattering" are the same as for proposal 5.
Latest version of name: volume_backwards_scattering_coefficient_at_stp_in_air_due_to_pm2p5_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1 i.e. multiplied by density have standard names with "specific_" instead of "volume_". Backwards scattering refers to the sum of scattering into all backward angles i.e. scattering_angle exceeds pi/2 radians. A scattering_angle should not be specified with this quantity. The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity descri
bed by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm2p5" refers to the fraction of aerosol particles with an aerodynamic diameter of less than or equal to 2.5 micrometers, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa)."
Is this OK?
Status: still under discussion
14. surface_volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_pm10_dried_aerosol (m-1)
We need to add "particles" for consistency with the new "aerosol" definition and Brigitte's proposals. I have made modifications to the definition text for consistency with other "volume_scattering_coefficient" names. Can we agree to drop "surface"? My comments relating to "spherical_backscattering" are the same as for proposal 5.
Latest version of name: volume_backwards_scattering_coefficient_at_stp_in_air_due_to_pm10_dried_aerosol_particles (m-1)
"The volume scattering/absorption/attenuation coefficient is the fractional change of radiative flux per unit path length due to the stated process. Coefficients with canonical units of m2 s-1, i.e. multiplied by density, have standard names with "specific_" instead of "volume_". Backwards scattering refers to the sum of scattering into all backward angles i.e. scattering_angle exceeds pi/2 radians. A scattering_angle should not be specified with this quantity. The scattering/absorption/attenuation coefficient is assumed to be an integral over all wavelengths unless a coordinate of "radiation_wavelength" or "radiation_frequency" is included to specify the wavelength. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the quantity desc
ribed by the standard name applies, provide a scalar coordinate variable with the standard name of "relative_humidity". "pm10" refers to the fraction of aerosol particles with an aerodynamic diameter of less than or equal to 10 micrometers, where the size cut is applied under ambient conditions before aerosol humidity, pressure, or temperature are possibly altered. To specify the relative humidity at which the sample was sized, provide scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". 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. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa)."
Is this OK?
Status: still under discussion
15. surface_particle_number_concentration_at_stp_in_aerosol (m-3)
Can we agree to drop "surface"? I don't think it's correct to say "in_aerosol" because standard names usually say in_medium, where medium is air, sea_water, soil, etc. Also, I think "number_concentration" needs to go at the beginning of the name. I am wondering why "at_stp" is important for this name - how does it affect the number concentration? I have reworded the definition for consistency with existing names. With a bit of re-ordering we arrive at
Latest version of name: number_concentration_of_aerosol_particles_at_stp_in_air (m-3)
" "Number concentration" means the number of particles or other specified objects per unit volume. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "stp" means standard temperature (0 degC) and pressure (101325 Pa)."
Status: still under discussion
16. surface_particle_number_size_distribution_at_stp_in_dried_aerosol (m-3)
Can we agree to drop "surface"? I think the medium should be "in_air" rather than "in_dried_aerosol". "Distribution", in the statistical sense, is a new term within standard names, but a bit of re-ordering allows us to construct the name following similar syntax to existing histogram names. (We can't use "histogram" for this proposal because it is a distribution of number_concentration in m-3, not just a simple count). The original definition stated that the size intervals are logarithmic, which could be indicated by a size coordinate variable accompanied by appropriate bounds. If we are not too prescriptive about what the size intervals should be (i.e., linear, logarithmic, etc.) it makes the name more generally useful while still allowing Markus' data to be represented. Then we could have:
distribution_of_number_concentration_of_dried_aerosol_particle_size_at_stp_in_air (m-3)
However, I note that the definition also says "A coordinate variable of "electrical_mobility_particle_diameter" needs to be specified to indicate that the property applies at specific particle sizes". This is different to most (all?) other existing aerosol names whose definitions refer to aerodynamic sizes. If it is important that the particle sizing is carried out in a particular way then perhaps it ought to also be part of the name, which might lead to:
distribution_of_number_concentration_of_dried_aerosol_electrical_mobility_particle_size_at_stp_in_air (m-3)
This would be less generally applicable, but consistent with the definition (reproduced below).
"The particle number size distribution is the number concentration of aerosol particles per decadal logarithmic size interval as a function of particle diameter. "Aerosol" means the suspended liquid or solid particles in air (except cloud droplets). "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the property applies, provide scalar coordinate variable with the standard name of "relative_humidity". "surface" means that the property applies at the lower boundary of the atmosphere. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa). A coordinate variable of "electrical_mobility_particle_diameter" needs to be specified to indicate that the property applies at specific particle sizes."
I'm not sure which way to approach this one so more comments would be welcome.
Status: still under discussion
17. surface_cloud_condensation_nuclei_number_concentration_at_stp_in_aerosol (m-3)
Can we agree to drop "surface"? I think the medium should be "in_air" rather than "in_aerosol". Also, I think "number_concentration" needs to go at the beginning of the name. I must confess to ignorance concerning what determines whether an aerosol particle is also a cloud condensation nucleus (particle size perhaps?) . It would be useful to cover that in the definition, as otherwise it is hard to see why this quantity is different to proposal 15. I think (similar to 15) that the name itself should be:
number_concentration_of_cloud_condensation_nuclei_at_stp_in_air (m-3)
The current definition is:
"The cloud condensation nuclei number concentration is the total number of aerosol particles per unit volume independent of and integrated over particle size that act as condensation nuclei for liquid-phase clouds. "Aerosol" means the suspended liquid or solid particles in air (except cloud droplets). "surface" means that the property applies at the lower boundary of the atmosphere. "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa). A coordinate variable of "relative_humidity" needs to be specified to indicate that the property refers to a specific supersaturations with respect to liquid water."
Status: still under discussion
18. surface_cloud_condensation_nuclei_number_size_distribution_at_stp_dried_aerosol (m-3)
Can we agree to drop "surface"? I think the medium should be "in_air" rather than "in_dried_aerosol". As with proposal 16, we could follow "histogram" syntax to arrive at:
distribution_of_number_concentration_of_cloud_condensation_nuclei_size_at_stp_in_air (m-3)
but again I am wondering whether the method of sizing the particles should appear in the name:
distribution_of_number_concentration_of_cloud_condensation_nuclei_electrical_mobility_particle_size_at_stp_in_air (m-3)
The current definition is:
"The cloud condensation nuclei number size distribution is the number concentration of aerosol particles per decadal logarithmic size interval as a function of particle diameter that act as condensation nuclei for liquid-phase clouds. Coordinate variables of "electrical_mobility_particle_diameter" and "relative_humidity" should be specified to indicate that the property refers to specific particle sizes and supersaturations with respect to liquid water. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Dried_aerosol" means that the aerosol sample has been dried from the ambient state before sizing, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the sample was sized, provide a scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". stp" means standard temperature (0 degC) and pressure (101325 Pa)."
I'd welcome comments on this.
Status: still under discussion
That concludes my comments! I feel that the majority of these names are now very close to acceptance and it would be great if we can bring them to a successful conclusion soon. Proposals 15-18 are the ones that probably still need the most discussion.
Best wishes,
Alison
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Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
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Received on Tue Nov 25 2014 - 10:26:37 GMT
