Dear Markus,
Thank you for getting back to me about your proposals and sorry for the delay in responding. The full summary of all your proposals and their current status can be viewed in the standard names editor at
http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=&proposerfilter=Markus&descfilter=&unitfilter=&yearfilter=&filter+and+display=Filter. (Accepted names have amber title bars, names under discussion have greeny/brown title bars).
We are now agreed on dropping "surface", adding "particles" and also on the use of "backwards_scattering" rather than "spherical_backscattering". This has led to proposal (2) being dropped because the removal of "surface" from the term made it identical to proposal (1). This also allows the following proposals to be accepted for publication in the standard name table, (in addition to those that were accepted previously):
(5) volume_backwards_scattering_coefficient_in_air_due_to_dried_aerosol_particles (m-1)
(15) surface_particle_number_concentration_at_stp_in_aerosol (m-3)
I have adjusted the definition text for "dried aerosol" to remove any reference to "sizing", as requested. The "dried_aerosol" definition now reads:
" "Dried_aerosol" means that the aerosol sample has been dried from the ambient state, but that the dry state (RH < 40%) has not 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". " This has been used in all cases where the phrase appears in the name.
However, I still have a question regarding sizing in "pm" name definitions as exemplified by my comments on proposal (6) below.
6. volume_scattering_coefficient_at_stp_in_air_due_to_pm1_dried_aerosol_particles (m-1)
Sorry, but I'm a bit confused now about the coordinate variables in the definition. Currently it reads:
"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%) has not 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". "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 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)."
In your last message you replied to this by saying:
> 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".
In your comment on proposal (3) you also wrote:
> 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.
In this case the sample is being sized, so surely we do need to refer to it in the definition? If I've understood the order of events correctly, ambient aerosol is first sampled by sizing it (hence pm1) and the coordinate variable for that process is relative_humidity_for_aerosol_particle_size_selection. (It could also be described as "ambient relative humidity" but that's not what has been proposed). The sized sample is then dried to some humidity which is greater than 40% but less than ambient, given by the relative_humidity coordinate variable, at which point the scattering coefficient is measured. Is that right? If so, I believe the current definition is correct, isn't it? If I have got this muddled, please could you write out in full what the definition should be?
The same question also applies to your comments on proposals 7, 8, 9, 10, 11, 12 , 13, 14,
where again you have said:
> 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".
If we can clarify this point, then I think that proposals 6 - 14 could be accepted immediately.
16. Thank you for the additional explanation of the size distribution names - I hadn't fully understood how these properties are calculated. Of your two proposed solutions, I think the first is most elegant:
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. Depending on the measurement method, one coordinate variable such as "electrical_mobility_particle_diameter", "optical_particle diameter", or "aerodynamic_particle_diameter" should be specified to indicate that the property applies at specific particle sizes and how the size was obtained. "log10_X" means common logarithm (i.e. base 10) of X. "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%) has not 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". "stp" means standard temperature (0
degC) and pressure (101325 Pa)."
I think it is fine to propose the use of alternative coordinate variables in this way as we sometimes do with radiation_wavelength and radiation_frequency, for example. It also means that the standard name itself is more general and not tied to a specific method of measurement.
You have proposed that this would be accompanied by the addition of two further coordinate variable standard names, similar to the electrical_mobility_particle_diameter that has already been accepted. I have reworded the definitions slightly.
optical_particle_diameter (m)
"The diameter of spherical particles whose presence in a medium would result in the same refractive index and lead to the same intensity of scattered light as the particles in question."
aerodynamic_particle_diameter
"The diameter of a spherical particle with density 1000 kg m-3 having the same aerodynamic properties as the particles in question."
I think it is actually very useful to add the aerodynamic_particle_diameter name, since we refer to "aerodynamic diameter" in the definition of existing names, but we have never had any text explaining what that means!
These three names are accepted for inclusion in the standard name table.
17. number_concentration_of_cloud_condensation_nuclei_at_stp_in_air (m-3)
"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. A coordinate variable with the standard name of relative_humidity should be specified to indicate that the property refers to a specific supersaturation with respect to liquid water. A particle's ability to act as a condensation nucleus is determined by its size, chemical composition, and morphology. "stp" means standard temperature (0 degC) and pressure (101325 Pa)."
Thank you for the clarification - this looks fine now. This name is accepted for publication in the standard name table.
18. Again I prefer your first solution and this would also then be consistent with proposal (16). I have altered the wording of the definition slightly so that it reads consistently with the definitions of (16) and (17).
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 with the standard name of relative_humidity should be specified to indicate that the property refers to a specific supersaturation with respect to liquid water. A coordinate variable with the standard name of electrical_mobility_particle_diameter should be specified to indicate that the property applies at specific mobility particle sizes. 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 particle's ability to act as a condensation nucleus is determined by its size, chemical composition, and morphology. "log10_X" means common logarithm (i.e. base 10) o
f X. "stp" means standard temperature (0 degC) and pressure (101325 Pa)."
This name is accepted for inclusion in the standard name table.
You mentioned a number of additional proposals in your last email. I have added them as follows:
21. volume_scattering_coefficient_at_stp_in_air_due_to_ambient_aerosol_particles (m-1)
The name and units are consistent with others we have already agreed. Following our earlier discussions the definition of this name would be:
"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. "Ambient_aerosol" means that the aerosol is measured or modelled at the ambient state of pressure, temperature and relative humidity that exists in its immediate environment. "Ambient aerosol particles" are aerosol particles that have taken up ambient water through hygroscopic growth. The extent of hygroscopic growth depends on the relative humidity and the composition of the particles. To spe
cify 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. 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. "stp" means standard temperature (0 degC) and pressure (101325 Pa)."
Is this OK?
22. volume_scattering_coefficient_at_stp_in_air_due_to_dried_aerosol_particles (m-1)
The name and units are consistent with others we have already agreed. Following our earlier discussions the definition of this name would be:
"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%) has not 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". The specification of a physical process by the phrase "due_to_" process means that the quant
ity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "stp" means standard temperature (0 degC) and pressure (101325 Pa)."
Is this OK?
23. volume_absorption_coefficient_at_stp_in_air_due_to_dried_aerosol_particles (m-1)
The name and units are consistent with others we have already agreed. Following our earlier discussions the definition of this name would be:
"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%) has not 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". The specification of a physical process by the phrase "due_to_" process means that the quant
ity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "stp" means standard temperature (0 degC) and pressure (101325 Pa)."
Is this OK?
24. volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_dried_aerosol_particles (m-1)
volume_backwards_scattering_coefficient_at_stp_in_air_due_to_dried_aerosol_particles (m-1)
In our earlier discussions we agreed that "spherical_backscattering" should be replaced by "backwards_scattering" in all cases, which would make these two names identical. I assume that the intention was actually just to propose the second one - is that right? We would then have
volume_backwards_scattering_coefficient_at_stp_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" 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%) has not necessarily been reached. To specify the relative humidity at which the sample was m
easured, 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. "stp" means standard temperature (0 degC) and pressure (101325 Pa)."
Is this OK?
I am planning to publish an update to the standard name table imminently (today or tomorrow if possible). All the "accepted" names will be included automatically. I will schedule another update of standard names in January so that any names agreed after today's update can be included then.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/Centre for Environmental Data Archival Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
Received on Thu Dec 18 2014 - 09:25:18 GMT
