Dear Alison,
thanks once more for taking this forward!
I have responded to your comments by item inline below. In short, I agree with
dropping the "surface" term from the proposed standard names, and replace
"aerosol" with "aerosol_particles". I don't know what happened to the list of
proposed names in the course of discussion, but I would also need the following
variants of the proposed names on the list as well (the definitions follow the
same philosophy as below):
volume_scattering_coefficient_at_stp_in_air_due_to_ambient_aerosol_particles (m-1)
volume_scattering_coefficient_at_stp_in_air_due_to_dried_aerosol_particles (m-1)
volume_absorption_coefficient_at_stp_in_air_due_to_dried_aerosol_particles (m-1)
volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_dried_aerosol_particles
volume_backwards_scattering_coefficient_at_stp_in_air_due_to_dried_aerosol_particles
(m-1)
All the best!
Markus
Am 25.11.2014 um 18:26 schrieb alison.pamment at stfc.ac.uk:
> 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.
MF: Yep!
> 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.
MF: Perfect.
> 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.
MF: It is also my understanding that we agreed to drop the "surface" term. That
will be the fastest, easiest, and probably best solution.
> 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.
MF: Agreement with both!
> 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 co
ordinate 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.
MF: Agreed!
> 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.
MF: No, we don't need the separate "surface" term.
> 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
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.
MF: In defining "dried aerosol", the definition text refers to "sizing". The
measurement of the scattering coefficient, unless referring to PM10 or PM1,
doesn't involve sizing. However, the scattering coefficient still depends on
relative humidity. Can we change the following sentences in the definition?
"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".
to
"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 sample was measured, provide a scalar coordinate variable with the standard name of "relative_humidity".
> 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
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.
MF: Same comment as for 3.
>
> 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"?
MF: Yes to use "particles" and drop "surface", but also here the comment I made
for 3. applies.
>
> 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
if 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
that 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
MF: I think your line of argument is rather convincing, accepted! Also, I see
that this definition text already includes my comment to 3, which would be
important.
>
> 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 aerodyn
amic 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
MF: Yes, ok, but please change
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".
to
To specify the relative humidity at which the sample was measured, provide a scalar coordinate variable with the standard name of "relative_humidity".
>
> 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 aer
odynamic 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
MF: OK, but please drop the sentence
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".
>
> 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 aero
dynamic 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
MF: Agreement to use "particles" and drop "surface", but please also drop the
sentence:
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".
>
> 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 aerodyn
amic 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
MF: Agreement to use "particles" and drop "surface", but please also drop the
sentence:
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".
>
> 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 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
MF: Agreement to use "particles" and drop "surface", but please also drop the
sentence:
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".
>
> 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 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
MF: Agreement to use "particles" and drop "surface", but please also drop the
sentence:
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".
>
> 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 desc
ribed 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
MF: Agreement to use "particles" and drop "surface", but please also drop the
sentence:
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".
>
> 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 desc
ribed 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
MF: Agreement to use "particles" and drop "surface", but please also drop the
sentence:
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".
>
> 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 de
scribed 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
MF: Agreement to use "particles" and drop "surface", but please also drop the
sentence:
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".
>
> 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
MF: Agreed! Let's drop "surface", and use "in_air". The "at_stp" is important
since we deal with concentrations in a volume, not a mixing ratio. For
concentrations, you need reference temperature and pressure. This is similar to
optical coefficients, which in fact also are concentrations (of scattering /
absorption cross-section per volume).
>
> 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
MF: The property to be named here isn't just a concentration of particles
falling into distinct size ranges. The concentration is normalised to the size
interval it applies to, and aerosol scientists usually don't use the linear size
interval for normalising, but the base 10 logarithmic one (for good reasons too
long to explain here). This is done precisely to be independent of the
individual selection of size intervals in the size distribution. All this is
implicit when an aerosol scientist talks about particle size distribution.
However, I see the problem of occupying the term "size distribution" with such a
specific definition in the context of a generic framework such as CF. Concerning
the way of sizing, I see the options of giving this information in the
co-ordinate variable , or in addition in the name itself. This would lead to the
following options:
1)
log10_size_interval_based_number_size_distribution_of_dried_aerosol_particles_at_stp_in_air (m-3)
The particle number size distribution is the number concentration of aerosol particles, normalised to the decadal logarithmic size interval the concentration applies to, 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_for_aerosol_particle_size_selection". "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa). Depending on the measurement method, one coordinate variable such as ?electrical_mobility_particle_diameter?, "optical_particle diameter", or "aerodynamic_particle_diameter" needs to be specified to indicate that the property applies at specific particle sizes and how the size was obtained
.
2)
log10_size_interval_based_electrical_mobility_number_size_distribution_of_dried_aerosol_particles_at_stp_in_air (m-3)
log10_size_interval_based_aerodynamic_number_size_distribution_of_dried_aerosol_particles_at_stp_in_air (m-3)
log10_size_interval_based_optical_number_size_distribution_of_dried_aerosol_particles_at_stp_in_air (m-3)
The particle number size distribution is the number concentration of aerosol particles, normalised to the decadal logarithmic size interval the concentration applies to, 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_for_aerosol_particle_size_selection". "at_stp" refers to a volume at standard conditions of temperature (273.15 K) and pressure (1013.25 hPa). "Electrical mobility" / "aerodynamic" / "optical" refers to the method used to determine the particle diameter. Depending on the measurement method, one coordinate variable such as ?electrical_mobility_particle_diameter?, "optical_particle diameter", or "aerodynamic_particle_diameter" need
s to be specified to indicate that the property applies at specific particle sizes and how the size was obtained.
Both options would require 2 additional co-ordinate variables:
optical_particle_diameter (m)
Diameter of a spherical particle with given refractive index creating the same
intensity of scattered light as the concerned particle.
aerodynamic_particle_diameter
Diameter of a spherical particle with density 1000 kg/m^3 having the same
aerodynamic properties as the concerned particle.
>
> 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 supersaturation with respect to liquid water."
>
> Status: still under discussion
MF: I can agree to your modification of the name. For the definition, we can
drop the "surface" sentence, and replace the "aerosol" sentence with this one:
A particle's ability to act as condensation nucleus is determined by its size,
chemical composition, and morphology.
>
> 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
MF: Drawing in the conclusions from items 16. and 17., I would propose the
following options:
1)
log10_size_interval_based_number_size_distribution_of_cloud_condensation_nuclei_at_stp_in_air (m-3)
The cloud condensation nuclei number size distribution is the number concentration of aerosol particles, normalised to the decadal logarithmic size interval the concentration applies to, as a function of particle diameter, where the particle acts as condensation nucleus for liquid-phase clouds. A coordinate variable "relative_humidity" should be specified to indicate the supersaturation with respect to liquid water where the property applies. To specify the relative humidity at which the particle sizes were selected, provide a scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". A coordinate variable ?electrical_mobility_particle_diameter? needs to be specified to indicate that the property applies at a specific mobility particle size. "at_stp" means standard temperature (0 degC) and pressure (101325 Pa).
2)
log10_size_interval_based_electrical_mobility_number_size_distribution_of_cloud_condensation_nuclei_at_stp_in_air (m-3)
The cloud condensation nuclei number size distribution is the number concentration of aerosol particles, normalised to the decadal logarithmic size interval the concentration applies to, as a function of particle diameter, where the particle acts as condensation nucleus for liquid-phase clouds. A coordinate variable "relative_humidity" should be specified to indicate the supersaturation with respect to liquid water where the property applies. To specify the relative humidity at which the particle sizes were selected, provide a scalar coordinate variable with the standard name of "relative_humidity_for_aerosol_particle_size_selection". A coordinate variable ?electrical_mobility_particle_diameter? needs to be specified to indicate that the property applies at a specific mobility particle size. "at_stp" means standard temperature (0 degC) and pressure (101325 Pa).
>
> 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
>
> ------
> 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.
>
>
>
--
Dr. Markus Fiebig
Senior Scientist
Dept. Atmospheric and Climate Research (ATMOS)
Norwegian Institute for Air Research (NILU)
P.O. Box 100
N-2027 Kjeller
Norway
Tel.: +47 6389-8235
Fax : +47 6389-8050
e-mail: Markus.Fiebig at nilu.no
skype: markus.fiebig
P Please consider the environment before printing this email and attachments
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