Dear Alison,
thanks for keeping up with this proposal, and apologies from my side for letting
it idle for so long, especially since we are so close to finishing it. Here are
my comments by item:
Am 18.12.2014 um 17:25 schrieb alison.pamment at stfc.ac.uk:
> 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.
MF: After re-reading my earlier comments to this point, I need to admit that I
was probably misunderstanding what you wrote. You are right, for the pmX
properties, we should have one variable,
relative_humidity_for_aerosol_particle_size_selection, to indicate the humidity
while sizing or selecting the size range, and one indicating the humidity for
when the property was measured, relative_humidity. That means that we can accept
proposals 6 - 14.
> 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.
MF: Perfect, then let's consider this version as accepted. I will comment on the
definition of "optical_particle_diameter" when responding on Armin's mail on the
same topic.
MF: Also, all of the definitions below (21 - 24) are just fine and should be
considered accepted.
Thanks so much for your effort!!!!!
Best regards,
Markus
>
> 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 s
pecify 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 qua
ntity 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 qua
ntity 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
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 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?
>
>
--
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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