Talk:CF Standard Names - CF Standard Names - Submitted Atmospheric Chemistry and Aerosol Terms

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This page contains the emails discussing the table on submitted atmospheric chemistry and aerosol terms, Version 6: 11.07.2007

Contents

Discussion launched by Christiane Textor, July 11

Dear aerosol and chemistry modellers,

I would like to ask for your comments on the standard names for the CF conventions for aerosols and chemistry, mainly concerning their sources and sinks, and optical thickness.

It is important that these names are checked by many people because they have to be understandable across communities. It would be very helpful if you could have a quick look!!

The names can be found at:

http://wiki.esipfed.org/index.php/CF_Standard_Names_-_CF_Standard_Names_-_Submitted_Atmospheric_Chemistry_and_Aerosol_Terms

In May, about 30 names have been accepted:
http://wiki.esipfed.org/index.php/CF_Standard_Names_-_Accepted_names_for_aerosols_and_chemistry
http://cf-pcmdi.llnl.gov/documents/cf-standard-names/5/cf-standard-name-table.html

THANK YOU VERY MUCH FOR YOUR TIME!

Best regards, Christiane

Mian Chin, July 12: mixed aerosols/optical thickness

Christiane,

The names are pretty clear to me, except the sulfate, nitrate, and ammonium aerosol optical depth parts: Because ammonium has to be associated with sulfate and nitrate (or other anions), it is not an independent aerosol species; I am not sure the meaning of "ammonium aerosol".

Also, I think the terms of SO2 gas phase destruction, SO2 aqueous phase destruction, (or sulfate gas phase and aqueous phase production), SO2 gas phase production, DMS gas phase destruction should be included in the "tendencies due to chemical reactions" category.

Mian

Reply from Christiane Textor, July 12

Dear Mian,

Thank you very much for your valuable comments.

Concerning the optical thickness AOT per species: in reality most aerosols are internally mixed, i.e. associated with other species, but AOT is calculated from the sum of the contributing species in most cases. This is why I have defined the names, in accordance what we had used in AeroCom.

For ionic components, it becomes even more tricky. We had e.g. sulfate optical thickness AOT in AeroCom.

What would you suggest to describe these values?

Thank you very much for your comments in advance.

Cheers, Christiane

Reply from Frank Dentener, July 12

Hi Mian; I understand what you say- but you'll have the same discussion with e.g. water in ambient aerosol: it can not exist without other component. It is the consequence of artificially seperating the components of an internally mixed aerosol system. I do not think that in practice it will cause problems. f

Reply from Michael Schulz, July 12

Hi Frank, Mian and especially Christiane,

As Frank said: I understand what you say. However, I would say that in practice this AOD business indeed created and will create problems. I fear even for HTAP we need to reask modellers what they really provided. So the only way (for the future) would be to elaborate on the clear definition of what the variables mean.

1) I propose that we clearly state which dry mass is associated to a given AOD. If we wish to describe the dry soluble mass in terms of salts, then we have to express that in the name.

So I think we need to propose in addition to
atmosphere_optical_thickness_due_to_sulfate_ambient_aerosol
atmosphere_optical_thickness_due_to_ammonium_ambient_aerosol
atmosphere_optical_thickness_due_to_nitrate_ambient_aerosol
atmosphere_optical_thickness_due_to_sodium_ambient_aerosol
(note: if only "sulfate" is given I would assume, that no ammonium is associated to it)

the following:
atmosphere_optical_thickness_due_to_ammonium_sulfate_ambient_aerosol
atmosphere_optical_thickness_due_to_ammonium_bi_sulfate_ambient_aerosol
atmosphere_optical_thickness_due_to_sulfuric_acid_ambient_aerosol
atmosphere_optical_thickness_due_to_ammonium_nitrate_ambient_aerosol
atmosphere_optical_thickness_due_to_sodium_nitrate_ambient_aerosol

For all these categories I propose the associated water has been either split according to volume of dry mass among aerosol components present in the soluble, mixed aerosol or according to a model derived water attribution. In any case the CF description should express the need that the sum of the species AOD should equal the total ambient AOD! However one has split the water and species. (nonlinear problems are for research papers.....)

I think it would also be needed to explain what this means:
atmosphere_optical_thickness_due_to_water_in_ambient_aerosol
To my understanding it is the difference between the total dry aerosol and the total ambient aerosol AOD.

well, well Michael

Reply from Frank Dentener July 13

comment on "atmosphere_optical_thickness_due_to_sulfate_ambient_aerosol"
I read here all sulfate both associated or not-associated with ammonium

comment on additional suggestions from Michael containing the salt-names:
it seems that the list of all possible stoechiometric combinations can become very long; is that still useful? for example associations of nitrate with dust (probably Ca(NO3)2) are missing. I am just wondering if you're not just generating enormous amounts of output that in the end will have to be put to gether anyhow to be analyzed? In AEROCOm would it have been usefull to now exactly with what the NH4 would have been associated?

FD agrees with Michael on "atmosphere_optical_thickness_due_to_water_in_ambient_aerosol is the difference between the total dry aerosol and the total ambient aerosol AOD":
yes for me too; it is the increase in aerosol radius due to water uptake ..

Reply from Michael Schulz July 13

Hi Frank et al,

I have thought about what you question (how many compounds to specify...) and somehow agree that it becomes too much. Just was an attempt.

Another idea to solve the dilemma is to define that cations (H+,NH4,NA,CA etc) are always implicitely associated to one of the anions or to sea salt or dust. As is water. As you somehow suggested first.

Which means we omit rather the ammonium AOD standard name! (we anyway have to re-ask the modellers what they did for the HTAP output. I see that quite some nh4 AODs are in the output. What did they do for the sulphate AOD...???)

And explain in the CF how sulfate and nitrate ambient AODs are meant!

We could keep the water AOD since it is a very useful diagnostic probably. Even Philip had it in his output.

all the best Michael

Reply from Mian Chin, July 14

All,

I was doing field measurements (for CALIPSO/AERONET) yesterday, and I just discovered earlier today all the emails about the CF names! Let me add more comments, and correct me if I am wrong:

1. Sulfate, nitrate, and ammonium aerosol optical depth:

I disagree with Frank. This is not an internal or external mixing issue and is not similar to the aerosol water/dry aerosol optical depth separation. Optical depth due to water uptake by aerosol can be easily obtained from the differences between ambient AOD and dry aerosol AOD, but the "ammonium" AOD cannot be obtained by excluding sulfate and/or nitrate, e.g., "sulfate" AOD is not the sum of "sulfate ion" AOD + "ammonium ion" AOD. "Sulfate" AOD is usually calculated as a product of sulfate (sulfuric acid, or ammonium sulfate, or ammonium bisulfate) mass and the corresponding mass extinction efficiency. I believe that in most models sulfate is either mostly ammonium sulfate or sulfuric acid in their sulfate AOD calculations. What is the mass extinction efficiency for "ammonium"? When calculating the ammonium AOD, one has to use the mass extinction for ammonium sulfate and/or ammonium nitrate, and that is what I meant that there is no independent ammonium AOD. In the case of water vapor, although it is not an independent "species", its apparent AOD can be easily extracted from the model and does not cause any confusion.

I might add that it is completely fine and useful to have individual mass or mass concentrations for sulfate, nitrate, and ammonium, but not the ammonium AOD.

2. CF names for aerosol species:

I think we should keep the list sufficiently short. I suggest: - ust use "atmosphere_optical_thickness_due_to_sulfate_ambient_aerosol" for any kind of sulfate AOD, but each model can provide supplemental information on what they mean by sulfate aerosol (or fraction of H2SO4, NH4HSO4, and (NH4)2SO4). I also feel that "atmospheric_optical_thickness_of_ambient_sulfate_aerosol" reads better.

- exclude ammonium AOD.

If we want to add all the cations and anions, the list will be enormous; besides, who can calculate the AOD from those ions? Furthermore, this list could expend rapidly to include, for example, all the organic matter species (which are highly unknown but there are groups who are sorting out the composition of POM), all the dust composition (SiO2, CaCO3, hematite, CaSO4, Ca(NO3)2, XYZ, whatever...), and seasalt ions... until everyone calls a quit.

Best,

Mian

Reply from Frank Dentener, July 16

OK mian, thanks for explaining.

I agree I think the combination from 'detailed' 3d aerosol fields; with simpler AOD will be fine.

Discussion would be worth (a bit cleaned up perhaps on Christiane's Wiki)=> otherwise will for sure re-appear.

f

Reply from Christiane Textor, July 22

Concluding from your discussions I would now like to suggest:

atmosphere_optical_thickness_due_to_sulfate_compounds_ambient_aerosol comment "Sulfate_compounds comprise all non-sea salt compounds containing sulfate that occur in the atmosphere (e.g. (NH4)2SO4, NH4HSO4, Na2SO4, NaHSO4, condensed H2SO4, etc). Please indicate the specific compounds you include in this variable.

atmosphere_optical_thickness_due_to_nitrate_compounds_ambient_aerosol comment "Nitrate_compounds comprise all compounds containing nitrate that occur in the atmosphere (e.g. NH4NO3, NaNO3, etc.). Please indicate the specific compounds you include in this variable.

I will delete the name atmosphere_optical_thickness_due_to_ammonium_ambient_aerosol

Please comment on this idea. Are the other names for the AOD ok? Please check on http://wiki.esipfed.org/index.php/CF_Standard_Names_-_CF_Standard_Names_-_Submitted_Atmospheric_Chemistry_and_Aerosol_Terms

The construction of the AOD names atmosphere_optical_thickness_due_to is consistent with other names of the CF conventions, which we should follow.

See also "Concept for construction of CF names for aerosols and chemistry, Christiane Textor, July 22" lower on this page.

Comment Michael 23.7.

atmosphere_optical_thickness_due_to_sulfate_compounds_ambient_aerosol ===> Good name

HOWEVER: For each AOD variable an explicit explanation is needed, for example:


The definition of the AOD of the aerosol component 'sulfate compounds' depends on the specific data set complexity. It comprises AOD contributions from all salt compounds containing sulphate, excluding natural sulphate in dust particles and natural sulphate found in primary seasalt particles. The sum of the AOD contributions from the aerosol components sulphate, nitrate, BC, POM, sea salt and dust is constructed such that it equals total aerosol AOD. The way how aerosol water is distributed among the above mentioned aerosol components shall be described by additional documentation to the specific data set. Aerosol water is otherwise assumed to be distributed proportional to the aerosol volume of the three most hygroscopic aerosol components sulphate, nitrate and sea salt before the aerosol component AOD of sulfate compounds is computed.

Mian Chin, July 12: additional names for sulfur chemistry SETTLED oR NOT SETTLED

Also, I think the terms of SO2 gas phase destruction, SO2 aqueous phase destruction, (or sulfate gas phase and aqueous phase production), SO2 gas phase production, DMS gas phase destruction should be included in the "tendencies due to chemical reactions" category.


Reply from Christiane Textor, July 12

Concerning the additional names you suggested, I agree that these might be needed, but as I replied to Yves: The philosophy of the CF convention is to only add names if they are actually needed. The names I have proposed have been used in HTAP.

Reply from Mian Chin, July 14

Christiane, I think the names I suggested are indeed needed because they are the only diagnostics for sulfate source. We should have them for HTAP.

Reply from Christiane Textor, July 22

Hi Mian,

If these names will be used in the next HTAP round they should indeed be included in the CF conventions. Please tell me if this is the case.

comment Michael -- MichaelSchulz 15:57, 23 July 2007 (EDT)

I dont think this is "settled", since Mian rightly expresses that it was an omission in HTAP. In a lot of AeroCom output this variable is present and thus used. The parameters are used and will be used to clarify the sulfur budget mysteries in the different models!

Yves Balkanski, July 12: addition of names for natural/anthropogenic components SETTLED

Hello all,

You did not distinguish between the natural and the anthropogenic component. Did you ever condider doing it? If I take a file with optical depth, I would be interested to know it, would that be a subfield?

Thanks

Yves

Reply from Christiane Textor, July 12

Dear Yves,

Thank you very much for your comment! The philosophie of the CF convention is to only add names if they are actually needed. The names I have proposed have been used in HTAP, and the distinction between anthropogenic/natural was not included.

Cheers, Christiane

Arlene Fiori, July 13: NOy, POM, chemical_gross_production SETTLED

Hi Christiane,

They look fine to me. A few minor points:

(1) NOy explanations could also include HONO, and add "expressed as mass of nitrogen" to be consistent with the explanations for other species. I realize it's in the name itself, but might not hurt to have it both places (also for NOx).

(2) Is tendency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_ae rosol_due_to_chemical_net_production_and_emission = tendency_of_atmosphere_mass_content_of_secondary_particulate_organic_mat ter_dry_aerosol_due_to_chemical_net_production + + tendency_of_atmosphere_mass_content_of_primary_particulate_organic_matte r_dry_aerosol_due_to_emission ?

If so, it seems redundant to have all 3 but maybe I'm misunderstanding.

(3) in the "chemical_gross_production" terms, seems like "gross_chemical_production" would be a more logical ordering

Arlene --

Reply from Christiane Textor, July 12

Dear Arlene,

Thank you very much for your comments! Please find my answers below:

> (1) NOy explanations could also include HONO, and add "expressed as mass of nitrogen" to be consistent with the explanations for other species. I realize it's in the name itself, but might not hurt to have it both places (also for NOx).

Added!

> > (2) Is >tendency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_aerosol_due_to_chemical_net_production_and_emission
>= tendency_of_atmosphere_mass_content_of_secondary_particulate_organic_matter_dry_aerosol_due_to_chemical_net_production
>+tendency_of_atmosphere_mass_content_of_primary_particulate_organic_matter_dry_aerosol_due_to_emission ? > > If so, it seems redundant to have all 3 but maybe I'm misunderstanding. >

You are right that the third equals the sum of the first two. Sum models do not distinghuish between prim. and sec. and this is why I also proposed the total.

> (3) in the "chemical_gross_production" terms, seems like "gross_chemical_production" would be a more logical ordering

I thought it would be better to attach the 'gross' prefix to 'production', because their are potentially other processes than chemical, e.g. biological.

Cheers, Christiane

Christiane Textor, July 13: Why 'tendency' and not 'flux'? SETTLED

Hello again,

Thank you very much for your comments so far!

Michael Schulz has asked me, why I propose 'tendency' instead of 'flux' for emission, deposition and chemical production, and I would like to explain this here.

I did this because the term 'flux' is related to a change per unit area. This does apply to deposition to and emission from the surface, but not to emissions from airplanes or fires, or to the production of secondary aerosols. The term 'tendency' just means a change in time, no dimension is associated with it.

I thought it would be confusing to use for some variables the term 'flux' and for others the term 'tendency'. Therefore, I have proposed

tendency_of_atmosphere_mass_content_of_species_due_to_process

The term 'mass_content' indicates a vertical integral: "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used." from the CF web site.

It would be very helpful if you could just send a short comment which solution you prefer:

      • MIXED use of 'flux' and 'tendency'
      • GENERAL use of 'tendency'

Thank you very much!

Cheers, Christiane

Reply from Frank Dentener, July 13

tendency seems to be the appropriate term. f

Reply from Yves Balkanski, July 13

I propose that you use the term tendency and not mix up flux and tendency (which might generate more questions!). The units will indicate unambiguously if it is a flux or not.

Yves

Conclusion from Christiane Textor, July 22

We stick to the GENERAL use of 'tendency'

Michael Schulz, July 13: What is POM? SETTLED

I have another funny question for you all: Is BC included in POM????

Reply from Frank Dentener, July 16

Is this a trick question?
No it shouldn't it is purely elemental carbon whereas by definition organic contains some H's and other elements to make it organic.

Reply from Christiane Textor, July 2

This information is already included in the comment on the POM names, e.g., for mass_fraction_of_particulate_organic_matter_dry_aerosol_in_air:
Mass fraction is used in the construction mass_fraction_of_X_in_Y, where X is a material constituent of Y. It means the ratio of the mass of Y to the mass of X (including Y). Particulate organic matter means all (primary and secondary) particulate organic matter aerosol, expect for black carbon. "Aerosol" means the suspended liquid or solid particles in air (except cloud droplets). Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol" means aerosol without water.

Concept for construction of CF names for aerosols and chemistry, Christiane Textor, July 22

Much of the discussion here applies to the names for aerosols and chemistry in general.
E.g., mass_content_of_sulfate_dry_aerosol: is this pure sulfate or does it include all kations? I understand pure SO4, but if you define an aerosol_optical_thickness_due_to_sulfate as sulfate plus all kations, mass and AOD variables do not correspond with each other any more. Consequently, a different result would be obtained for the mass extinction coefficient that is calculated from the fraction...

The construction of the CF names is described on http://wiki.esipfed.org/index.php/CF_Standard_Names_-_Construction_of_Atmospheric_Chemistry_and_Aerosol_Terms but this page is somewhat outdated, as I do not have much time at the moment. We should probably work on these ideas, as also suggested by Philip J. Cameron-smith on the CF mailing list, see
http://www.cgd.ucar.edu/pipermail/cf-metadata/2007/001772.html
"Would it make more sense to represent chemical quantities under CF by splitting the standard name into two pieces, e.g. 'Quantity_of_X' and X_is_species_name'?"

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