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<center>'''''General discussion on [[CF Standard Names - Proposed Atmospheric Chemistry and Aerosol Terms]].'''''</center> 
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==CTextor:Initial Chemistry and Aerosol Terms==
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Go to [[Agreed Items of Discussion Proposed_Atmospheric_Chemistry_and_Aerosol_Terms| Agreed Items of Discussion on Proposed Atmospheric Chemistry and Aerosol Terms]].
Please have a look at the [[CF Standard Names - Proposed Atmospheric Chemistry and Aerosol Terms| wiki page of proposed names]] Comments are highly welcome ! Please forward the web site adress to those who might be interested but not considered in this email. I will be back in my office on June 1. --[[User:ChristianeTextor|ChristianeTextor]] 16:51, 22 May 2006 (EDT)
 
  
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---
  
==JGregory: CF Email List==
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Important issues are marked in '''<font color="Red">RED </font>''', please COMMENT!
:Thanks for your page. Perhaps you might like to post your comments to the CF email list. In that case I would post these responses: --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
 
===......RHusar: CF Email List===
 
::Posting Christiane's initial naming effort to the CF e-mail list would indeed be helpful for connecting the CF community with this "domain expert" group. We have also agreed earlier that the content these wiki pages, including the discussion pages will be transferred to a more neutral domain. --[[User:Rhusar|Rhusar]] 19:19, 22 May 2006 (EDT)
 
===......CTextor: CF Email List===
 
::I will send an email to the CF email list, or will you do it, Jonathan?--[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
 +
<br>
 +
=NOy=
 +
'''Vincent-Henri PEUCH VHP - CT - Jonathan Gregory JG - Frank Dentener FD - David Stevenson DS, June/July 2006'''
 +
:'''(VHP)''' There is always the problem that "NOy" has no fully agreed definition in the literature... It is perhaps unwise to use it in the name? Could we use "total_nitrogen_oxides" instead?
 +
:'''(JG)''' I think it's a good idea to avoid the word "total" if we can, as it is not always obvious what aspect is being totalled! total_nitrogen_oxides is probably clear enough, but maybe all_nitrogen_oxides might be better?
 +
:'''(CT)''' But what does 'all' include? anyway, I changed it.
 +
:'''(FD)''' NOy it is a matter of defining accurately. Total Nitrogen is a very confusing term, in biological applications it may mean something completely different. NOy=NO+NO2+HNO3+NO3aerosol+2 N2O5 + NO3(radical) + HNO4 + PAN + other organic nitrates.
 +
:'''(CT)''' some models might not have all these species, I define it now as:
 +
::standard_name: atmosphere_mole_fraction_of_all_nitrogen_oxides
 +
::explanation: volume mixing ratio of nitrogen oxides NOy, i.e., sum of moles_fractions of all simulated oxidized nitrogen species, (NO, NO2, HNO3, NO3aerosol, N2O5, NO3(radical), HNO4, PAN, other organic nitrates) (N2O5 is only counted once!)
 +
:'''(CT)''' Another difficulty arises from N2O5, that contains to N atmos. Frank wrote 2*N2O5 in his definition, but if we count in mole or kg - not kgN!, this is not correct. Therefore, I have added (N2O5 is only counted once!)
 +
:'''(DS)''' Follow Frank's definition, this is widely used. This is valid for all species expressed as mole fractions (or volume mixing ratios). This is the most common usage in atmospheric chemistry.
 +
:'''(JG)''' I don't think you have to list them all explicitly, do you? Different people might have different lists of things in NOy. Can you state generally that it is expressed in moles of N, to get round the multiple counting?
 +
:'''(CT)''' But this is not UDUNITS!?!
  
==JGregory: Standard Names as Needed==
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=Tropopause definition - tropospheric column of gas phase species=
:We have a general principle that we haven't defined standard names until they are actually needed, to avoid our spending too much time worrying about issues that can't be properly resolved until we know the context, and hence making more mistakes than necessary. Do you need all the names you have listed now? If so, that's fine of course. --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
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'''Christiane Textor CT - Jonathan Gregory JG, June/July 2006'''
===......RHusar: Standard Names as Needed===
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* JG: You have a number of names of the form up_to_chemical_tropopause_content_of_X_in_air. This order is rather unnatural, I'd say. Also in_air probably isn't right, as here you mean a large-scale quantity. I know that we discussed whether "atmosphere" goes at the start or the end, and I remarked it usually was at the start, but a complete phrase is more awkward at the start. Would you consider X_content_of_chemical_troposphere or X_content_of_atmosphere_below_chemical_tropopause?''
::I would agree that the list of names should be pruned to the set that has been used. Is it fair to say that this initial list of chemical and aerosol names arose from chemical/aerosol model intercomparison studies? If so, one could start with the names used in the [http://nansen.ipsl.jussieu.fr/AEROCOM/ AEROCOM] model intercomparison project. After that we could identify the names that are needed to describe various in situ and remotely sensed observations. --[[User:Rhusar|Rhusar]] 19:19, 22 May 2006 (EDT)
 
===......CTextor: Standard Names as Needed===
 
::I included all names for gaseous chemical species proposed by PRISM, and added aerosol names from AeroCom, which were analyzed so far (i.e. not all AeroCom names). I will go throght the tables and include the input from our discussions.--[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
 +
:CT: I have put in_air because satellites only see the fraction in the gas phase, so atmosphere is not correct. below_chemical_tropopause sounds good. This would lead to X_mole_content_below_chemical_tropopause_in_air or  X_mole_content_in_air_below_chemical_tropopause. What do you think?
  
==JGregory: Content Explanation==
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:JG: X_mole_content_in_air_below_chemical_tropopause is fine
:We have used "content" in a lot of standard names to mean the amount of something per unit area i.e. a vertical integral. Do you think e.g. "atmosphere ozone content" in kg m-2 isn't clear enough terminology? --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
 
===......RHusar: Content Explanation===
 
::'Vertical burden' is also used to describe measured column concentrations. It may take a bit of getting used to, but I have no objections to  ozone_content. --[[User:Rhusar|Rhusar]] 19:19, 22 May 2006 (EDT)
 
===......CTextor: Content Explanation===
 
::I think in the chemistry/aerosol community "content" would rather be understood as a total mass, the amount of something per unit area would rather be called 'load' or 'column'. Therefore I would now suggest to use vertical_burden which seems less ambiguous to me. --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
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:CT: tropopause not yet defined!
  
==JGregory:in_air vs. atmosphere==
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=VHP: troposphere_content=
:The difference between atmosphere and in_air is that atmosphere is used to refer to large-scale properties, and in_air to locally measured ones. Hence the distinction between e.g. mass concentration in air, and atmosphere content. Chemical concentrations would be in_air (as you have done), and hence distinguished from in_sea_water etc. If a given quantity could appear in places other than air, it is correct to be explicit. --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
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'''Vincent-Henri PEUCH VHP - CT - DS, June/July 2006'''
 +
: The description of the "troposphere_content*" variables is not enough detailed because it is indeed verticaly integrated, but up to the tropopause only. We can specify in the explanation "up to the tropopause level", but we probably also have to specify the tropopause definition to be used (2PVU,380K ?) as the value is quite sensitive to the specific criterion used (for species with strong vertical gradients at the tropopause like ozone). A drawback of specifying is that any other type of hypotheses (other "tropopause" definition : 150 ppb of ozone, 100 hPa,...) or other ways of computation (specific tracer in the model) would then no longer fit with the name. I don't know the solution...
  
==JGregory: mole or mass fractions==
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::CT: The 150ppb O3 isosurface is a good measure for atmospheric chemsitry problems and has been used in ACCENT/PHOTOCOMP.
:You may indeed prefer mole_fraction for some quantities and mass_fraction for others. That would be your own decision for your project, but of course another project might make a different choice. --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
 
===......CTextor: mole or mass fractions===
 
::The use of either mole_  or mass_ fraction varies within the community, so I followed the suggestions of the PRISM project. But then aerosols should allways be in mass and gases in mole fraction for consistency. --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
==JGregory: Units==
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::DS: We used the monthly mean 150 ppbv O3 isosurface as a post-processing mask on all monthly mean 3-D fields in the ACCENT work. This worked well, but may be less appropriate for instantaneous model fields, and/or in high resolution models (e.g. boundary layer ozone in a very polluted episode may exceed 150 ppbv; and a recently incorporated tropopause fold may also). We also had to be careful to define the mask for one case (e.g. the year 2000 base scenario) and then use it for all cases (e.g. various future emissions scenarios), otherwise the mass (or volume) of tropospheric air changes. One disadvantage is that the mass (or volume) of the troposphere then varies between models; this problem will occur for any definition, but perhaps shows less variation for better known definitions such as the WMO tropopause. We chose the chemical tropopause method because it had been used previously (IPCC 2001) and was easy to implement in post-processing (i.e. it didn't rely on modellers). If you are asking modellers to define tropospheric column amounts then that is open to problems. I would just ask for full model 3-D fields and calculate tropospheric columns in a consistent way in post-processing. If a variety of tropopause definitions is also asked for (WMO, 2PVU, 380K...) then you can use whichever you like when it comes down to it. But don't ask the modellers to do it, as they will all do something different.
:It doesn't matter to CF what units are used, so long as they are udunits. Any dimensionally equivalent unit can be used for a given standard name.
 
However, kgC and kgS aren't SI units. I think the unit has to be kg. This implies that it's the standard name which must somehow indicate that it is the
 
mass of C or mass of S which is being referred to, rather than the mass of the compound e.g. dry_deposition_flux_of_sulfur_as_sulfate_at_surface.
 
--[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
 
===......CTextor: Units===
 
::changed for carbon, sulfate, and nitrogen species --[[User:Christiane|Christiane]] 15:53, 8 June 2006 (EDT)
 
{|{{prettytable}}
 
|-
 
| width="321" Height="12,75" | mass_concentration_of_sulfate_as_sulfate_aerosol_in_air
 
  
|-
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:: CT: Thank you very much for you comment, it sound very good to me. I will post your suggestion to the GEMS people.
| Height="12,75" | mass_concentration_of_nitrate_as_nitrate_aerosol_in_air
 
  
|-  
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=CT: Several tropopause definitions exist=
| Height="12,75" | mass_concentration_of_ammonium_sulfate_aerosol_in_air
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'''CT, June/July 2006'''
 +
: - chemical tropopause (150 ppb O3 isosurface)
 +
: - lapse rate tropopause (the lowest level at which the lapse rate decreases to 2 °C/km or less,
 +
:    provided that the average lapse rate between this level and all higher levels within 2 km does not exceed 2 °C/km. WMO definition of Tropopause)
 +
: - potential vorticity (PVU2 (at the 2 PVU surface) or PVU1.5 (at the 1.5 PVU surface))
 +
: - potential temperature surface
 +
:DS: Ask for them all, as suggested above. You don't need to use them all.
  
|-  
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=JG: tropopause_defined_by_...=
| Height="12,75" | mass_concentration_of_seasalt_aerosol_in_air
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'''JG- CT, June/July 2006'''
 +
:If you need to distinguish different definitions of the tropopause, this could be done by defining different standard names. This issue is rather like the definition of the ocean mixed layer, for which we have several standard names:
 +
::''ocean_mixed_layer_thickness_defined_by_mixing_scheme''
 +
::''ocean_mixed_layer_thickness_defined_by_sigma_t''
 +
::''ocean_mixed_layer_thickness_defined_by_sigma_theta''
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::''ocean_mixed_layer_thickness_defined_by_temperature''
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::''If there are particular numbers which are needed for the definition (like your 150 ppb O3) they could be specified as standard name parameters (but we still haven't agreed the mechanism for this!).''
  
|-
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:CT: This would then give X_mole_content_in_air_below_tropopause_defined_by_150ppv_O3_iso_surface.
| Height="25,5" | mass_concentration_of_organic_carbon_aerosol_from_terpenes_as_particulate_organic_carbon_aerosol_in_air
 
  
|-
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:JG: For X_mole_content_in_air_below_tropopause_defined_by_150ppv_O3_iso_surface: I was thinking it is better avoid putting "parameter" like 150 ppb in the name. When it is necessary to record such parameters to define a standard name, we should use some other attribute. This has come up before and I refer to them as "standard name parameters" but we have not decided how it should be done! For instance, it could be a new attribute, or it could be a scalar coordinate variable. This needs to be debated. I think a generic name such as X_mole_content_in_air_below_tropopause_defined_by_ozone_mole_fraction would be all right, and we could mention the 150 ppb in the definition (for the moment).
| Height="25,5" | mass_concentration_of_organic_carbon_as_particulate_organic_carbon_aerosol_in_air
 
  
|-
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:CT: X_mole_content_in_air_below_tropopause_defined_by_ozone_mole_fraction is the new name so far, but the tropopause definition is still not agreed on, it could be:
| Height="25,5" | mass_concentration_of_hydrophilic_organic_carbon_as_particulate_organic_carbon_aerosol_in_air
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::tropopause_defined_by_ozone_mole_fraction
 +
::tropopause_defined_by_temperature_lapse_rate
 +
::tropopause_defined_by_potential_vorticity
 +
::tropopause_defined_by_potential_temperature
  
|-  
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=VHP: mole_fraction_of_ozone_from_stratosphere_in troposphere=
| Height="25,5" | mass_concentration_of_hydrophobic_organic_carbon_as_particulate_organic_carbon_aerosol_in_air
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'''VHP-JG, June/July 2006'''
 +
:The variable "mole_fraction_of_ozone_from_stratosphere_in troposphere" is a modeler's concept, with no chance of being measured. The way it is implemented in a model has an impact on the actual values, due to non linearities etc... I would not be in favor of including it as a standard variable. What do you think?
  
|-
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:JG "The variable mole_fraction_of_ozone_from_stratosphere_in troposphere is a modeler's concept." Yes, that is true, but if modellers want to store this quantity, and compare it among models, then it should be given a standard name. There are many quantities like this, which aren't really observable. To begin with CF was designed for models, rather than the real world!
| Height="12,75" | mass_concentration_of_black_carbon_aerosol_in_air
 
  
|-  
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=Construction of deposition flux names=
| Height="12,75" | mass_concentration_of_hydrophilic_black_carbon_aerosol_in_air
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'''Jonathan Gregory - Christiane Textor (CT)''', '''June/July 2006'''
 +
* I would suggest that due_to_turbulence comes after of_X, because there could be a quantity dry_deposition_flux_of_X, of which dry_deposition_flux_of_X_due_to_turbulence is a part.
 +
:''(CT) It is :dry_deposition_mole_flux_of_X=dry_deposition_mole_flux_of_X_due_to_turbulence+dry_deposition_mole_flux_of_X_due_to_sedimentation, so I would rather like to leave the due_to_turbulence and due_to_sedimentation close to deposition, so I would like to change it to  dry_deposition_mole_flux_of_X=dry_deposition_due_to_turbulence_mole_flux_of_X+dry_deposition_due_to_sedimentation_mole_flux_of_X, ok?
  
|-  
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=Grid box area=
| Height="12,75" | mass_concentration_of_hydrophobic_black_carbon_aerosol_in_air
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'''Jonathan Gregory JG - Christiane Textor CT - Martin Schultz MS''','''June/July 2006'''
  
|-
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JG: Do you have a data variable containing area? If the only purpose of this is to provide weights, you can use cell_measures to supply the area variable (CF 7.2). However if you do have them as data variables, I agree you need a standard name. I'd suggest surface_area. I think this is really the quantity, isn't it. It is analogous to sea_ice_area (m2), for example. These are extensive quantities in space; they implicitly depend on the size of the grid box.
| Height="12,75" | mass_concentration_of_dust_aerosol_in_air
 
  
|}
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CT: I reread the CF documentation yesterday and realized the possibility of using the cell methods for the grid information, sorry for that. We do not need an additional standard_name.
  
==JGregory: equivalent_thickness_at_stp_of_atmosphere_ozone_content==
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MS: I am not convinced that this is a good decision. In atmospheric chemistry, the term "surface area" is much more common for "surface_area_of_leaves" (i.e. for calculating biogenic emissions), or "aerosol_surface_area" (i.e. for computing heterogeneous reaction rates). I think that the term gridbox_area is much more clear in describing what the variable contains. A really detailed standard name might be "gridbox_surface_area".
:equivalent_thickness_at_stp_of_atmosphere_ozone_content means the thickness (depth) of the layer you would get by collecting all the ozone in the atmospheric column at STP. It was named like that by analogy with the equivalent thickness (depth) of amounts of precipitation. Does that make sense? --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
 
===......RHusar: Aerosol Scale Height===
 
::I wonder if we can use the same naming for aerosol_scale_height, i.e. the height of an aerosol layer if the concentration was vertically uniform between the surface and scale height. --[[User:Rhusar|Rhusar]] 19:27, 22 May 2006 (EDT)
 
===......CTextor: equivalent_thickness_at_stp_of_atmosphere_ozone_content===
 
::The problem for me is STP, I realize that it is 'standard temperature and pressure'. I found it on wikipedia so I guess I should know...? --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
 +
DS: Also ask for 'gridbox_volume' and 'gridbox_mass'. These are very useful for calculating integrated quantities without having to worry about model grids (especially vertical grids).
  
==JGregory: Variable and File Names==
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=total atmospheric columns=
:Names for variables and files would not be the subject of CF conventions --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
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'''VHP - CT, June/July 2006'''
===......CTextor: Variable and File Names===
 
::I agree that this is not the focus of the CF conventions, but is still needed for model intercomparisons. We might want to open another discussion on the structure and names of files elsewhere. --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
 +
VHP: we could add, for ozone at least, "total_atmosphere_content_of_*_in_air" (in Dobson units for ozone, mol/m2 for others if needed).
  
==JGregory: Avoid Abbreviations==
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CT: I have added "atmosphere_content_of_*_in_air" in mole/m2. total_ is not necessary, this is already included in atmospere if there is no other specification. Dobson units are not possible within the concept of CF which is based on UDUNITS, see also the discussion on [http://wiki.esipfed.org/index.php/Talk:Units units].
:We try to avoid abbreviations like "turdry" and "seddry". Although they make the names longer, I think these should be spelled out in full. Would this be a case for using due_to e.g. dry_deposition_..._due_to_turbulence? --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
 
===......CTextor: Avoid Abbreviations===
 
::I will change this. --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
 +
=3d emissions=
 +
'''CT - JG, July 2006'''
  
==JGregory: Distinction between Net and Total Production==
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CT: I have defined surface_ and atmosphere_ emissions, e.g.
:It could be unclear to have a distinction between "production" and "net production". Is there a more explicit name for the former? Can you call it "gross production", for instance, like gross/net primary productivity of ecosystems? --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
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::surface_emission_mole_flux_of_ozone mole/m2/s
===......CTextor: Distinction between Net and Total Production ===
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::atmosphere_emission_mole_flux_of_ozone mole/m3/s.  
:changed --[[User:Christiane|Christiane]] 17:54, 2 June 2006 (EDT)
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::Is it allowed to have a flux per m3?
  
==JGregory: IUPAC Rule?==
+
JG: Interesting! It's not really a flux, is it - not a flow through an area, which is what flux means to me. I think we may need to consider using a different word. What word is usually used in atmos chem for this?
:Some of your species names are not [http://www.chem.qmul.ac.uk/iupac/ IUPAC]. Can you give a clear rule which can be consistently applied about when to allow non-IUPAC names? --[[User:JonathanGregory|JonathanGregory]] 16:51, 22 May 2006 (EDT)
 
===......CTextor: IUPAC Rule?===
 
::Of course, I will check this.... I did. Could you please tell me which are not correct? Thank you!  --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
  
==CTextor: articles and prepositions==
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CT: It is still an emission, and to my knowledge we would call it 3d-emissions. Maybe we would call it simply 'source' to distinguish from 'flux'? Or delete 'flux' in all names related to deposition and emission. We should be consistent with    chemical_gross_mole_fraction_production_rate_of_G_in_air [1/s]. Question forwarded to GEMS-evaluators...
:Articles and prepositions should be avoided? --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
 
 
 
 
==CTextor: large scale compartment==
 
:Some species can occur in the ocean and in atmosphere, should we allways give atmosphere/ocean/soil? --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 
 
 
 
 
==CTextor: ion / radical names==
 
:How to distinguish ion - radicals, e.g. NO3? such difficulty might not occur with the names that are needed now, but certainly in the future. --[[User:Christiane|Christiane]] 12:11, 2 June 2006 (EDT)
 

Latest revision as of 07:47, July 11, 2007

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Go to Agreed Items of Discussion on Proposed Atmospheric Chemistry and Aerosol Terms.

---

Important issues are marked in RED , please COMMENT!


NOy

Vincent-Henri PEUCH VHP - CT - Jonathan Gregory JG - Frank Dentener FD - David Stevenson DS, June/July 2006

(VHP) There is always the problem that "NOy" has no fully agreed definition in the literature... It is perhaps unwise to use it in the name? Could we use "total_nitrogen_oxides" instead?
(JG) I think it's a good idea to avoid the word "total" if we can, as it is not always obvious what aspect is being totalled! total_nitrogen_oxides is probably clear enough, but maybe all_nitrogen_oxides might be better?
(CT) But what does 'all' include? anyway, I changed it.
(FD) NOy it is a matter of defining accurately. Total Nitrogen is a very confusing term, in biological applications it may mean something completely different. NOy=NO+NO2+HNO3+NO3aerosol+2 N2O5 + NO3(radical) + HNO4 + PAN + other organic nitrates.
(CT) some models might not have all these species, I define it now as:
standard_name: atmosphere_mole_fraction_of_all_nitrogen_oxides
explanation: volume mixing ratio of nitrogen oxides NOy, i.e., sum of moles_fractions of all simulated oxidized nitrogen species, (NO, NO2, HNO3, NO3aerosol, N2O5, NO3(radical), HNO4, PAN, other organic nitrates) (N2O5 is only counted once!)
(CT) Another difficulty arises from N2O5, that contains to N atmos. Frank wrote 2*N2O5 in his definition, but if we count in mole or kg - not kgN!, this is not correct. Therefore, I have added (N2O5 is only counted once!)
(DS) Follow Frank's definition, this is widely used. This is valid for all species expressed as mole fractions (or volume mixing ratios). This is the most common usage in atmospheric chemistry.
(JG) I don't think you have to list them all explicitly, do you? Different people might have different lists of things in NOy. Can you state generally that it is expressed in moles of N, to get round the multiple counting?
(CT) But this is not UDUNITS!?!

Tropopause definition - tropospheric column of gas phase species

Christiane Textor CT - Jonathan Gregory JG, June/July 2006

  • JG: You have a number of names of the form up_to_chemical_tropopause_content_of_X_in_air. This order is rather unnatural, I'd say. Also in_air probably isn't right, as here you mean a large-scale quantity. I know that we discussed whether "atmosphere" goes at the start or the end, and I remarked it usually was at the start, but a complete phrase is more awkward at the start. Would you consider X_content_of_chemical_troposphere or X_content_of_atmosphere_below_chemical_tropopause?
CT: I have put in_air because satellites only see the fraction in the gas phase, so atmosphere is not correct. below_chemical_tropopause sounds good. This would lead to X_mole_content_below_chemical_tropopause_in_air or X_mole_content_in_air_below_chemical_tropopause. What do you think?
JG: X_mole_content_in_air_below_chemical_tropopause is fine
CT: tropopause not yet defined!

VHP: troposphere_content

Vincent-Henri PEUCH VHP - CT - DS, June/July 2006

The description of the "troposphere_content*" variables is not enough detailed because it is indeed verticaly integrated, but up to the tropopause only. We can specify in the explanation "up to the tropopause level", but we probably also have to specify the tropopause definition to be used (2PVU,380K ?) as the value is quite sensitive to the specific criterion used (for species with strong vertical gradients at the tropopause like ozone). A drawback of specifying is that any other type of hypotheses (other "tropopause" definition : 150 ppb of ozone, 100 hPa,...) or other ways of computation (specific tracer in the model) would then no longer fit with the name. I don't know the solution...
CT: The 150ppb O3 isosurface is a good measure for atmospheric chemsitry problems and has been used in ACCENT/PHOTOCOMP.
DS: We used the monthly mean 150 ppbv O3 isosurface as a post-processing mask on all monthly mean 3-D fields in the ACCENT work. This worked well, but may be less appropriate for instantaneous model fields, and/or in high resolution models (e.g. boundary layer ozone in a very polluted episode may exceed 150 ppbv; and a recently incorporated tropopause fold may also). We also had to be careful to define the mask for one case (e.g. the year 2000 base scenario) and then use it for all cases (e.g. various future emissions scenarios), otherwise the mass (or volume) of tropospheric air changes. One disadvantage is that the mass (or volume) of the troposphere then varies between models; this problem will occur for any definition, but perhaps shows less variation for better known definitions such as the WMO tropopause. We chose the chemical tropopause method because it had been used previously (IPCC 2001) and was easy to implement in post-processing (i.e. it didn't rely on modellers). If you are asking modellers to define tropospheric column amounts then that is open to problems. I would just ask for full model 3-D fields and calculate tropospheric columns in a consistent way in post-processing. If a variety of tropopause definitions is also asked for (WMO, 2PVU, 380K...) then you can use whichever you like when it comes down to it. But don't ask the modellers to do it, as they will all do something different.
CT: Thank you very much for you comment, it sound very good to me. I will post your suggestion to the GEMS people.

CT: Several tropopause definitions exist

CT, June/July 2006

- chemical tropopause (150 ppb O3 isosurface)
- lapse rate tropopause (the lowest level at which the lapse rate decreases to 2 °C/km or less,
provided that the average lapse rate between this level and all higher levels within 2 km does not exceed 2 °C/km. WMO definition of Tropopause)
- potential vorticity (PVU2 (at the 2 PVU surface) or PVU1.5 (at the 1.5 PVU surface))
- potential temperature surface
DS: Ask for them all, as suggested above. You don't need to use them all.

JG: tropopause_defined_by_...

JG- CT, June/July 2006

If you need to distinguish different definitions of the tropopause, this could be done by defining different standard names. This issue is rather like the definition of the ocean mixed layer, for which we have several standard names:
ocean_mixed_layer_thickness_defined_by_mixing_scheme
ocean_mixed_layer_thickness_defined_by_sigma_t
ocean_mixed_layer_thickness_defined_by_sigma_theta
ocean_mixed_layer_thickness_defined_by_temperature
If there are particular numbers which are needed for the definition (like your 150 ppb O3) they could be specified as standard name parameters (but we still haven't agreed the mechanism for this!).
CT: This would then give X_mole_content_in_air_below_tropopause_defined_by_150ppv_O3_iso_surface.
JG: For X_mole_content_in_air_below_tropopause_defined_by_150ppv_O3_iso_surface: I was thinking it is better avoid putting "parameter" like 150 ppb in the name. When it is necessary to record such parameters to define a standard name, we should use some other attribute. This has come up before and I refer to them as "standard name parameters" but we have not decided how it should be done! For instance, it could be a new attribute, or it could be a scalar coordinate variable. This needs to be debated. I think a generic name such as X_mole_content_in_air_below_tropopause_defined_by_ozone_mole_fraction would be all right, and we could mention the 150 ppb in the definition (for the moment).
CT: X_mole_content_in_air_below_tropopause_defined_by_ozone_mole_fraction is the new name so far, but the tropopause definition is still not agreed on, it could be:
tropopause_defined_by_ozone_mole_fraction
tropopause_defined_by_temperature_lapse_rate
tropopause_defined_by_potential_vorticity
tropopause_defined_by_potential_temperature

VHP: mole_fraction_of_ozone_from_stratosphere_in troposphere

VHP-JG, June/July 2006

The variable "mole_fraction_of_ozone_from_stratosphere_in troposphere" is a modeler's concept, with no chance of being measured. The way it is implemented in a model has an impact on the actual values, due to non linearities etc... I would not be in favor of including it as a standard variable. What do you think?
JG "The variable mole_fraction_of_ozone_from_stratosphere_in troposphere is a modeler's concept." Yes, that is true, but if modellers want to store this quantity, and compare it among models, then it should be given a standard name. There are many quantities like this, which aren't really observable. To begin with CF was designed for models, rather than the real world!

Construction of deposition flux names

Jonathan Gregory - Christiane Textor (CT), June/July 2006

  • I would suggest that due_to_turbulence comes after of_X, because there could be a quantity dry_deposition_flux_of_X, of which dry_deposition_flux_of_X_due_to_turbulence is a part.
(CT) It is :dry_deposition_mole_flux_of_X=dry_deposition_mole_flux_of_X_due_to_turbulence+dry_deposition_mole_flux_of_X_due_to_sedimentation, so I would rather like to leave the due_to_turbulence and due_to_sedimentation close to deposition, so I would like to change it to dry_deposition_mole_flux_of_X=dry_deposition_due_to_turbulence_mole_flux_of_X+dry_deposition_due_to_sedimentation_mole_flux_of_X, ok?

Grid box area

Jonathan Gregory JG - Christiane Textor CT - Martin Schultz MS,June/July 2006

JG: Do you have a data variable containing area? If the only purpose of this is to provide weights, you can use cell_measures to supply the area variable (CF 7.2). However if you do have them as data variables, I agree you need a standard name. I'd suggest surface_area. I think this is really the quantity, isn't it. It is analogous to sea_ice_area (m2), for example. These are extensive quantities in space; they implicitly depend on the size of the grid box.

CT: I reread the CF documentation yesterday and realized the possibility of using the cell methods for the grid information, sorry for that. We do not need an additional standard_name.

MS: I am not convinced that this is a good decision. In atmospheric chemistry, the term "surface area" is much more common for "surface_area_of_leaves" (i.e. for calculating biogenic emissions), or "aerosol_surface_area" (i.e. for computing heterogeneous reaction rates). I think that the term gridbox_area is much more clear in describing what the variable contains. A really detailed standard name might be "gridbox_surface_area".

DS: Also ask for 'gridbox_volume' and 'gridbox_mass'. These are very useful for calculating integrated quantities without having to worry about model grids (especially vertical grids).

total atmospheric columns

VHP - CT, June/July 2006

VHP: we could add, for ozone at least, "total_atmosphere_content_of_*_in_air" (in Dobson units for ozone, mol/m2 for others if needed).

CT: I have added "atmosphere_content_of_*_in_air" in mole/m2. total_ is not necessary, this is already included in atmospere if there is no other specification. Dobson units are not possible within the concept of CF which is based on UDUNITS, see also the discussion on units.

3d emissions

CT - JG, July 2006

CT: I have defined surface_ and atmosphere_ emissions, e.g.

surface_emission_mole_flux_of_ozone mole/m2/s
atmosphere_emission_mole_flux_of_ozone mole/m3/s.
Is it allowed to have a flux per m3?

JG: Interesting! It's not really a flux, is it - not a flow through an area, which is what flux means to me. I think we may need to consider using a different word. What word is usually used in atmos chem for this?

CT: It is still an emission, and to my knowledge we would call it 3d-emissions. Maybe we would call it simply 'source' to distinguish from 'flux'? Or delete 'flux' in all names related to deposition and emission. We should be consistent with chemical_gross_mole_fraction_production_rate_of_G_in_air [1/s]. Question forwarded to GEMS-evaluators...