Dear Alison,
thanks for a great job on keeping the CF names consistent and keeping the ball
rolling!!!
I agree with Martin, I think your suggestions make lots of sense. I hesitated a
little at first concerning your proposal of mentioning particles twice in some
names (PM - particulate matter, POM - particulate organic matter, together with
aerosol_particles), but found your argument convincing. It is good practise to
keep established terms together. This will make life easier for search
algorithms and other applications that need to parse the individual parts of
standard names. You had one point where you wanted some comments specifically
from my side:
3. Number concentrations
The proposed number_concentration names don't specify the type of aerosol:
number_concentration_of_pm10_in_air;
number_concentration_of_pm2p5_in_air.
Do these refer to dry or ambient aerosol? To be consistent with the other names we need something like
number_concentration_of_pm10_dry_aerosol_particles_in_air.
For the number concentration, it makes no significant difference whether the
aerosol is dry or at ambient humidity. Let me explain that. The particle number
concentration in atmospheric aerosol is dominated by particles smaller than
about 800 nm. Letting these particles grow by uptake of humidity won't change
their number, only their size. That means, if you apply a size cut, e.g. PM10,
some particles will grow out of this size range when going from dry state to
ambient state. However, since there are very few particles by number in the
range around 10?m, this effect isn't measurable, it is only of theoretical
relevance. For comparison, another systematic uncertainty in the above name
definition is the use of the PM10 size cut, which refers to 10?m aerodynamic
particle diameter. Most models use the spherical equivalent geometric particle
diameter. When going from there to the aerodynamic diameter, you need
assumptions on particle density and shape. This, even theoretically, unavoidable
systematic uncertainty in the above name definition is of the same order as the
one caused by going from dry to ambient aerosol state. I would thus for
practical reasons propose a structure like:
number_concentration_of_pm10_aerosol_particles_in_air
thus avoiding an apparent precision in the definition that can't be achieved. If
desired, we can add the essence of this discussion as a comment in the standard
name definition.
I'm presently working on a revised version of my proposal that will reflect your
conclusions.
Best regards,
Markus
Am 21.11.2014 um 13:18 schrieb alison.pamment at stfc.ac.uk:
> Dear Brigitte, Markus and Martin,
>
> I have reviewed the discussion of all the HTAP names proposed by Brigitte at the beginning of this year. This is in preparation for making an update to the standard name table. I am also in the process of reviewing Markus Fiebig's own proposals (see http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/056946.html and follow up posts) as the discussions of the two sets of names overlap. I will post later today about Markus' names.
>
> I have given my detailed comments on the HTAP names below. Due to the large number of proposals for new names and amendments to existing names I have not listed them all individually in this email. The full list of names affected by Brigitte's proposals can be viewed at
> http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=&proposerfilter=Brigitte+Alison&descfilter=&unitfilter=&yearfilter=&filter+and+display=Filter which shows them as they currently appear in the CF names editor. Names with an amber title bar are accepted for publication and will appear in the next version of the standard name table. Names with a title bar that appears greenish/brownish (depending on your display screen) are still under discussion. Below the title bar of each name and at the right of the screen you will also see a coloured label which indicates whether the proposal relates to a new name, creation of an alias (term change), or an updated definition.
>
> I intend to publish an update to the standard name table within the next week, concentrating on aerosol names. I will then begin preparation of another update which will focus mainly on remote sensing names, but will also include some other, smaller sets of proposals that have been agreed recently.
>
> 1. Summary of status of HTAP proposals
>
> 89 of 103 proposals for new names are accepted for publication; 2 others can be accepted without change to the name if my suggestions to modify the definitions can be agreed; 9 need some minor amendments to the names themselves and 3 need further clarifications of the definitions.
>
> All 138 existing aerosol names have been reviewed and aliases created to change "aerosol" to "aerosol_particles" in the vast majority of cases. This was agreed in the overlapping discussions of Markus' and Brigitte's proposals. 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."
>
> The definitions of 32 existing nmvoc (non methane volatile organic compound) names have been updated. The expanded text is as follows: " "nmvoc" means non methane volatile organic compounds; "nmvoc" is the term used in standard names to describe the group of chemical species having this classification that are represented within a given model. The list of individual species that are included in a quantity having a group chemical standard name can vary between models. Where possible, the data variable should be accompanied by a complete description of the species represented, for example, by using a comment attribute."
>
> Aliases have been created for 18 existing "black_carbon" names to change to using "elemental_carbon" for consistency with the new names. For the moment I have not changed two black carbon optical names (I will send a separate email about these). In addition, the definitions of 23 existing particulate organic matter names have been changed to refer to "elemental carbon" instead of "black carbon".
>
> 2. Definitions of aqueous and gaseous phase chemistry
>
> For the standard name tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_particles_due_to_aqueous_phase_net_chemical_production, you provided a brief definition of aqueous phase chemical production: " aqueous phase (fog and clouds) is meant as opposed to gaseous phase." I suggest expanding this for clarity and consistency with the existing "net chemical production" definition as follows:" "Aqueous phase net chemical production" means the net result of all aqueous chemical processes in fog and clouds that produce or destroy a species, distinct from atmospheric chemical processes in the gaseous phase."
> Is this OK? The name itself is fine.
>
> Similarly, for the standard name tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_particles_due_to_gaseous_phase_net_chemical_production, I suggest amending the wording of your gaseous_phase definition as follows:" "Gaseous phase net chemical production" means the net result of all gaseous chemical processes in the atmosphere that produce or destroy a species, distinct from chemical processes in the aqueous phase."
> Is this OK? The name itself is fine.
>
> 3. Number concentrations
>
> The proposed number_concentration names don't specify the type of aerosol:
> number_concentration_of_pm10_in_air;
> number_concentration_of_pm2p5_in_air.
> Do these refer to dry or ambient aerosol? To be consistent with the other names we need something like
> number_concentration_of_pm10_dry_aerosol_particles_in_air.
>
> 4. Particulate organic matter
>
> Some proposals use the expression "particulate_organic_matter", e.g., mass_fraction_of_particulate_organic_matter_dry_aerosol_particles_expressed_as_carbon_in_air whereas in other cases, e.g. mass_fraction_of_pm2p5_primary_organic_matter_dry_aerosol_particles_in_air , the term 'particulate' is omitted from the species. While it is true that referring to 'particulate_organic_matter' and 'aerosol_particles' in the same name does sound somewhat repetitive, we need to standardize on a single approach to these names.
>
> 'Particulate_organic_matter' is often abbreviated to 'POM', which is widely used in literature, and this suggests to me that we should retain it in the species name for ease of identification. See for example the US EPA environment dictionary http://www.ecologydictionary.org/PARTICULATE_ORGANIC_MATTER_%28POM%29 . There are 44 existing particulate_organic_matter standard names.
>
> The term 'aerosol_particle' was discussed at length in both this thread and Markus'. It was introduced to distinguish between "aerosol" meaning the particulate component plus its carrier gas and the particulate component alone.
>
> To ensure consistency with the definitions of both phrases, and despite the apparent repetitiveness, I think that all the organic matter aerosol proposals should include both the particulate_organic_matter and aerosol_particle phrases. I have accepted those proposals that do use both phrases and suggest that the remainder be altered to follow the same pattern.
>
> Thus the following six names are accepted:
> tendency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_aerosol_particles_due_to_emission
> tendency_of_atmosphere_mass_content_of_secondary_particulate_organic_matter_dry_aerosol_particles_due_to_emission
> tendency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_aerosol_particles_expressed_as_carbon_due_to_emission
> tendency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_aerosol_particles_expressed_as_carbon_due_to_dry_deposition
> endency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_aerosol_particles_expressed_as_carbon_due_to_wet_deposition
> mass_fraction_of_particulate_organic_matter_dry_aerosol_particles_expressed_as_carbon_in_air
>
> The following 6 remain 'under discussion' and I propose that for consistency they should be amended as shown:
> CHANGE
> mass_fraction_of_pm2p5_primary_organic_matter_dry_aerosol_particles_in_air
> TO
> mass_fraction_of_pm2p5_primary_particulate_organic_matter_dry_aerosol_particles_in_air
>
> CHANGE
> mass_fraction_of_pm2p5_organic_matter_dry_aerosol_particles_expressed_as_carbon_in_air
> TO
> mass_fraction_of_pm2p5_particulate_organic_matter_dry_aerosol_particles_expressed_as_carbon_in_air
>
> CHANGE
> mass_fraction_of_pm2p5_organic_matter_dry_aerosol_particles_in_air
> TO
> mass_fraction_of_pm2p5_particulate_organic_matter_dry_aerosol_particles_in_air
>
> CHANGE
> mass_fraction_of_pm10_organic_matter_dry_aerosol_particles_in_air
> TO
> mass_fraction_of_pm10_particulate_organic_matter_dry_aerosol_particles_in_air
>
> CHANGE mass_fraction_of_pm10_organic_matter_dry_aerosol_particles_expressed_as_carbon_in_air
> TO
> mass_fraction_of_pm10_particulate_organic_matter_dry_aerosol_particles_expressed_as_carbon_in_air
>
> CHANGE
> mass_fraction_of_pm10_primary_organic_matter_dry_aerosol_particles_in_air
> TO
> mass_fraction_of_pm10_primary_particulate_organic_matter_dry_aerosol_particles_in_air
>
> 5. Mass flux of ammonia
>
> The name surface_net_downward_mass_flux_of_ammonia_due_to_bidirectional_surface_exchange was proposed with definition: "Bidirectional surface exchange" is the exchange of a particular species between the atmosphere and biosphere as simulated by bidirectional surface flux models. "Downward" indicates a vector component which is positive when directed downward."
>
> Following the usual construction of standard names, "net_downward_mass_flux" would be defined as downward_mass_flux minus upward_mass_flux with a sign convention of downwards positive, as required by your definition. Therefore, I think the correct name should simply be "surface_net_downward_mass_flux_of_ammonia". I don't think we need the "bidirectional_surface_exchange" qualifier as it is already implied by the use of "net".
>
> 5) Fixed lifetime name.
>
> This proposal started life as two names: mole_fraction_of_carbon_monoxide_with_lifetime_of 25_days_in_air and
> mole_fraction_of_carbon_monoxide_with_lifetime_of 50_days_in_air. Martin Schultz suggested condensing these into a single name such as
> mole_fraction_of_synthetic_tracer_with_fixed_lifetime_in_air to be used with a new attribute tracer_lifetime. At a later stage the name seems to have changed again to mole_fraction_of_carbon_monoxide_with_fixed_lifetime_in_air, again with a tracer_lifetime attribute. The only suggested definition for this name is to require a comment attribute containing text such as "CO-like tracer with simple exponential decay loss term and a lifetime of 25 days."
>
> I think it is sensible to use one name for this quantity, however I'm not sure that introducing a new attribute is the best approach. If it is to be part of the CF conventions, a new attribute would require modification to the conventions document, rather than simply an addition to the standard name table. I would suggest as a simpler alternative that a scalar coordinate variable could be used to give the tracer lifetime - we could then introduce a new standard name of tracer_lifetime. The requirement to include the coordinate variable could be part of the definition of the name.
>
> Regarding the name itself, I am not clear what is meant by "CO-like tracer". I am also unsure as to whether "carbon_monoxide" or "synthetic_tracer" is the best way to label the species in these circumstances. Please can you explain a bit more.
>
> 7. Names needing further definition
>
> Two new proposals were added at the end of the discussion: (see http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2014/057372.html).
>
> canopy_resistance_to_ozone_dry_deposition (m-1 s)
> " The "canopy_resistance" is the resistance of a compound to uptake by the vegetation canopy. It varies both with the surface and the chemical species or physical state (gas or particle)."
>
> aerodynamic_resistance (m-1 s)
> "The "aerodynamic_resistance" is the resistance to mixing through the boundary layer toward the surface by means of the dominant
> process, turbulent transport."
>
> I am not very familiar with either of these quantities and no comments have been received on these proposals. A quick internet search suggests that both terms are in wide use in the literature.
>
> My (brief) research revealed that aerodynamic_resistance is sometimes termed "aerodynamic drag" which is more similar to existing standard names for heat, momentum and gravity wave drag. Perhaps "aerodynamic_drag" would therefore be more appropriate for this name? (I don't have a strong opinion either way). If it is a resistance to downward turbulent transport, then presumably that refers to transport of aerosol particles? Perhaps we should also put that in the name to make it more self explanatory, e.g., aerodynamic_drag_on_turbulent_deposition_of_aerosol_particles or resistance_to_turbulent_deposition_of_aerosol_particles_due_to_aerodynamic_drag. These are just suggestions and I'd welcome other opinions. Regarding the definition, it appears that there are a number of different formulae for this quantity (see for example the first paragraph of
> http://agsys.cra-cin.it/tools/evapotranspiration/help/Aerodynamic_resistance.html). Does this proposal relate to any particular formulation? If so, we should provide a reference in the definition.
>
> Regarding the canopy resistance name, could it be reworded to canopy_resistance_to_downward_flux_of_ozone_due_to_dry_deposition? Perhaps this more clearly relates the quantity to other atmospheric names? I don't know if that is useful and again it is just a suggestion. Also, if there is a particular formula or reference for this quantity we should include it in the definition.
>
> That concludes my somewhat lengthy comments! If we can agree any of the "under discussion" names over the next two or three working days then they can also be accepted in time for inclusion in the upcoming standard name table update.
>
> 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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