[CF-metadata] Clarifying standard names for 'mass_concentration_of_*_dry_aerosol_particles'

Daniel Neumann daniel.neumann at io-warnemuende.de
Thu Nov 9 07:52:41 MST 2017

Dear List,

I would like to bring this treat back to attention to finalize it in the 
one or another way. Further below are three suggestions ((a) to (c)) on 
how to proceed.

There are standard name types:
  - atmospheric_mass_content_of_X_dry_aerosol
  - mass_concentration_of_X_dry_aerosol_in_air

They are used in (a few) CMIP5, in (a few) CMIP6, in my, and, probably, 
in a lot of other data files.

The current status of discussion is that they DO NOT describe the "... 
mass of X ..." but the "... the mass of all particles containing X ...". 
These are quite different meanings. In practice, these standard names 
are used with the first meaning (at least CMIP5, CMIP6, my data). In 
practice, the second meaning is not applicable. I am not aware of any 
data set that uses one of these standard names 'correctly'.

Thus, the current status of the discussion is that the standard names 
are generally wrongly used. What shall we do? Here are three options.

The standard names do not 100% fit (if interpreted literally) to the 
variables to which they are applied.

(a) Nevertheless we keep them as they are to remain consistent and to 
avoid confusion. I volunteer to update the descriptions.
(b) We rename all these standard names (maybe 100 by number, probably more).
(c) We keep these standard names as they are (and enforce their literal 
meaning!) and create correct new standard names (maybe 100, probably more).

I am in favor of (a). Least work. Does not interfere with current usage.

The solution (b) would me a lot of hand work (if Batch processing of 
CF-Standard Name list is not possible -- is it?). The solution (c) would 
be quite bad (in my opinion): A lot of data set would not be 
CF-compliant anymore because 'wrong' standard names were used.

Why do I insist on finalizing this discussion: I would like to propose 
two new standard names, which are affected by this discussion.


On 13.07.2017 18:23, Daniel Neumann wrote:
> Dear Markus, Dear List,
> Thank you for your feedback.
> > doesn't make much sense beyond archiving a model output field since 
> it doesn't
> > describe any quantity that could be readily observed. Also, the mass
> > concentration of particles containing chemical X is somewhat 
> ill-defined. You
> > will find some traces of X in almost all particles of an aerosol 
> containing X -
> > so where is the threshold for saying that a particle contains X?
> I agree with you.
> Thus, it might be reasonable to introduce a new standard name (I like 
> the one you suggested. My idea for a name was more complicated :-) )
> mass_concentration_of_X_in_dry_aerosol_particles_in_air
> for (partly) secondary particulate species, namely nitrate, ammonium, 
> mercury, chloride, particulate organic matter, secondary particulate 
> organic matter and sulfate. For these species (except for chloride) 
> there exists already a standard name like
> mass_concentration_of_X_dry_aerosol_particles_in_air
> I think (please correct me if I am wrong) that
> mass_concentration_of_X_dry_aerosol_particles_in_air
> was meant to describe the same. Maybe one could make an alias from it?
> Regards,
> Daniel
> On 12.07.2017 14:32, Markus Fiebig wrote:
>> Dear Daniel,
>> thanks for posting this again, I missed your first posting during 
>> vacation.
>> Coming from the observation community, a name like
>> mass_concentration_of_X_dry_aerosol_particles_in_air
>> doesn't make much sense beyond archiving a model output field since 
>> it doesn't
>> describe any quantity that could be readily observed. Also, the mass
>> concentration of particles containing chemical X is somewhat 
>> ill-defined. You
>> will find some traces of X in almost all particles of an aerosol 
>> containing X -
>> so where is the threshold for saying that a particle contains X?
>> To me, it would make much more sense to have names of the type
>> mass_concentration_of_X_in_dry_aerosol_particles_in_air
>> This type of name is less ambiguous to understand, and describes a 
>> property that
>> can in fact be observed.
>> Best regards,
>> Markus
>> Am 11.07.2017 um 21:05 schrieb Daniel Neumann:
>>> Dear CF-Meta Mailinglist,
>>> I would like to advertise my long question from two weeks ago. Maybe 
>>> there
>>> were no replies because it was to long :-) . Excuse me if I should 
>>> be wrong
>>> with that assumption. The basic questions are:
>>> What do these two standard names mean?
>>>    (a) mass_concentration_of_ammonium_dry_aerosol_particles_in_air
>>>    (b) 
>>> mass_concentration_of_dry_aerosol_particles_expressed_as_ammonium_in_air 
>>> What should be the standard name for the mass concentration of 
>>> atmospheric
>>> particulate chloride/ammonium/nitrate/sulfate/...? Should it be like 
>>> (a), like
>>> (b) or something else (e.g. 
>>> mass_concentrations_of_particulate_ammonium_in_air)?
>>> Please find details on the question here:
>>> http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2017/059573.html
>>> Regards,
>>> Daniel
>>> On 27.06.2017 14:43, Daniel Neumann wrote:
>>>> Dear CF-Mailinglist,
>>>> in a recent proposal (link given below*), Alison and I discussed 
>>>> about the
>>>> naming conventions for the mass of specific aerosol particle 
>>>> components.
>>>> There seems to be clarification necessary in the descriptions 
>>>> and/or names.
>>>> [* recent proposal with discussion:
>>>> http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2017/059522.html, 
>>>> look for
>>>> "10. mass_concentration_of_chloride_dry_aerosol_particles_in_air 
>>>> (kg m-3)"]
>>>> Currently, there exist standard names like
>>>>> mass_concentration_of_ammonium_dry_aerosol_particles_in_air
>>>>> mass_concentration_of_dust_dry_aerosol_particles_in_air
>>>>> general form: mass_concentration_of_X_dry_aerosol_particles_in_air
>>>> which describe mass concentration of aerosol particles that contain 
>>>> species
>>>> X. Thus, this standard name describes not only the mass of species 
>>>> X but also
>>>> the mass of other species that are associated with X on particles. 
>>>> In the
>>>> past, I thought it would describe the mass of species X only. We 
>>>> think that
>>>> there is a need for clarifying this in the description of these 
>>>> standard names.
>>>> When we now want to quantify the mass of particulate X only (e.g. 
>>>> mass of
>>>> particulate chloride, mass of particulate ammonium), we could use the
>>>> standard name
>>>>> mass_concentration_of_dry_aerosol_particles_expressed_as_X_in_air
>>>> However, I see two problems with respect to this naming convention. 
>>>> First, we
>>>> get a not-nice name if we want to express the mass concentrations of
>>>> particulate ammonium in terms of nitrogen. We needed a standard 
>>>> name like
>>>> mass_concentration_of_dry_aerosol_particles_expressed_as_ammonium_expressed_as_nitrogen_in_air 
>>>> which contains 'expressed' twice.
>>>> Second (but that is my personal feeling only), I use the 
>>>> "X_expressed_as_Y"
>>>> formulation only, when there is some relation from Y to X. Or in 
>>>> other words:
>>>> when Y is a reasonable measure for X.
>>>>> ...organic_matter_..._expressed_as_carbon...
>>>>> ...nox_expressed_as_nitrogen...
>>>>> ...phytoplankton_expressed_as_phosphorus...
>>>> Therefore,
>>>> "mass_concentration_of_dry_aerosol_particles_expressed_as_X_in_air" 
>>>> is not a
>>>> good choice for a standard name describing the mass of particulate 
>>>> X in my
>>>> opinion.
>>>> An alternative would be to introduce a standard name like
>>>>> mass_concentrations_of_particulate_X_in_air
>>>>> mass_concentrations_of_particulate_ammonium_in_air
>>>>> mass_concentrations_of_particulate_chloride_in_air
>>>> What is your opinion on this topic?
>>>> Best Regards,
>>>> Daniel
>> -- 
>> 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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Daniel Neumann

Leibniz Institute for Baltic Sea Research Warnemuende
Physical Oceanography and Instrumentation
Seestrasse 15
18119 Rostock

phone:  +49-381-5197-287
fax:    +49-381-5197-114 or 440
e-mail: daniel.neumann at io-warnemuende.de

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