View source for CF Standard Names - Construction of Atmospheric Chemistry and Aerosol Terms

{{CF-links}}


'''This page provides the basis for the construction of CF standard names for atmospheric chemistry and aerosols.'''

The concepts described here have been developed since May 2006 for the definition of the 207 standard names that are accepted by the CF community as of October 2008.

The construction of CF standard names for aerosols and chemicals originated in the work of the PRISM project (Peter van Velthoven) see [http://proj.prism.enes.org/Results/Documents/WPs/WP4a/PRISM_standard_name_tables.html PRISM Standard Name Tables], latest Version, V 1.3. They have then been further developed on this wiki page and within the CF-mailing list. Important contributions come from the participating model intercomparison projects listed on the [[Air Quality/Chemistry Naming Conventions|entry page]]. 

The CF web site provides general [http://cf-pcmdi.llnl.gov/documents/cf-standard-names/guidelines Guidelines for Construction of CF Standard Names]. The CF standard names for aerosols and chemicals are composed of certain standard phrases and forms, following these guidelines. The concept is explained below in section 2.

At the moment, many new proposals for standard names for aerosols and chemicals are under discussion by the CF mailing list. Therefore, we (Christiane Textor with input from Martin Schultz, Heinke Hoeck, and Martina Stockhause) try to summarize the current status of work here, in order to highlight the principles and concepts we have developed so far. 

A large quantity of new standard names for chemical species, or for other topics, might be necessary in the future. This potential need has triggered a discussion on more general approaches to standard name construction (Thread "a different (but perhaps unoriginal) approach to standard name construction" launched by Karl Taylor.) 

Four main ideas for the construction of new standard names for chemical species have been discussed so far: 

# Definition of each chemically related standard name explicitly in the CF standard name list, and discussion of each of these names individually (current approach).
# Definition of groups of standard names (see below) with the individual chemical species or aerosol type given as a scalar coordinate. Names for individual species would not appear any more as CF standard names. Unphysical names would not occur, but the names would not be as human-understandable any more.
# Definition of groups of standard names (see below). Automated generation of explicit standard names based on these groups. Submit and accept all possible names, even if some of them might not have a physical meaning.
# Definition of groups of standard names (see below). Automated generation of explicit standard names based on these groups. Experts (possibly from the [http://www.igac.noaa.gov/ACandC.php AC&C model intercomparisons]) review these possible names and eliminate unphysical combinations before submission to and acceptance by the CF community.

Please note that the discussions of the aerosol and chemisty names in CF should be continued on the CF mailing list, and not on this wiki. The wiki is only used here to summarize the state of such names in CF. The descriptions below could help to converge to the most efficient strategy. (Please note, that [[Modfication of existing CF standard names|Modifications of existing CF standard names]] are suggested, if they do not fit in the general concepts explained below.)


<br />
----
<br />

=LIST OF ACCEPTED STANDARD NAMES FOR AEROSOLS AND CHEMICALS=

The list of standard names for aerosol ad chemicals accepted by October 29 2008 can be found [[LIST OF CHEMICAL SPECIES AND AEROSOLS|'''here''']].

=CONSTRUCTION OF STANDARD NAMES FOR AEROSOLS AND CHEMICALS=
<p>Certain <strong>phrases and forms</strong> are used: 
*chemical species and aerosols: describe the species
*physical quantity (generic names): describe the property of the species, and determine the unit of the variable
*processes: are used in derivatives of variables (e.g. fluxes): tendency_of_.... due_to_&lt;process&gt; and give the change of the species' property due to a certain process
*medium: indicates the local medium or layer within which the variable applies

These phrases and forms are combined to obtain the standard names, like for example
&lt;physical_quantity&gt;_of_X_in_&lt;medium
tendency_of_&lt;physical_quantity&gt;_of_X_in_&lt;medium&gt;_due_to_&lt;process&gt;

The combination of these phrases and names results in <strong>groups</strong> of Standard_Names that are given below. However, not all combinations are possible or reasonable.  

There are some odd names that do not fit in the general concepts. [[Modification of existing CF standard names|Modifications]] are suggested for these names in order to allow for the automatic creation of individual names from groups of CF standard names. </p>

==Phrases and forms==
===Chemical species and aerosols===
These can be chemical species with a defined molar mass (molecules, salts, etc.) or components that do not have a defined molar mass (aerosol, biological species)<br />
Goto to the [[list of chemical species and aerosols]] as of 29 October 2008.

===Physical Quantities===
angstrom_exponent [1]<br />
optical_thickness  [1]<br />
mass_content       [kg/m2]<br />
mass_fraction      [kg/kg]<br />
mass_concentration [kg/m3]<br />
mole_concentration [mole/m3]<br />
mole_fraction      [mole/mole]<br />
moles              [moles]<br />
tendency_of_&lt;Z&gt;_due_to_&lt;process&gt; (with Z=physical quantity of component, in units of per s)<br>
(Please note, that a discussion on the units might be necessary.)

===Processes===
dry_deposition <br />
emission <br />
re_emission <br />
wet_deposition <br />
net_production_and_emission <br />
dry_deposition_into_stomata <br />
&lt;no process=total changes&gt;

===Medium===
in_air <br />
in_sea_water<br />
in_atmosphere<br />
in_middle_atmosphere<br />
in_troposphere<br />

<p>or 
atmosphere used as a prefix (suggested to be changed)</p>

Please note that 'atmosphere' denotes all phases in the atmosphere and includes for example in_air, in_cloud, in_precipiation, etc.<br>
in_air means in the gas phase, a definition if this includes also water vapor (dry_air or wet_air?) would be needed.

==Groups of Standard_Names for chemicals and aerosols==
<p>The combination of the prases and forms given above results in groups of Standard_Names for chemicals and aerosols: </p>
<p>atmosphere_optical_thickness_due_to_&lt;A_ambient_aerosol&gt;<br />
atmosphere_optical_thickness_due_to_&lt;A_?dry?_aerosol&gt;<br />
mass_fraction_of_&lt;A_dry_aerosol&gt;_in_air<br />
mass_fraction_of_&lt;A_aerosol&gt;_in_air<br />
mass_concentration_of_&lt;A_?dry?aerosol&gt;_in_air<br />
mole_concentration_of_&lt;X&gt;_in_sea_water<br />
mole_fraction_of_&lt;G&gt;_in_air<br />
moles_of_&lt;G&gt;_in_atmosphere<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_dry_deposition<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_emission<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_re_emission<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_wet_deposition<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_net_production_and_emission<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_dry_deposition_into_stomata<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_wet_deposition<br />
tendency_of_atmosphere_mass_content_of_&lt;X&gt;_due_to_wet_deposition <br />
tendency_of_moles_of_&lt;G&gt;_in_atmosphere<br />
tendency_of_moles_of_&lt;G&gt;_in_middle_atmosphere<br />
tendency_of_moles_of_&lt;G&gt;_in_troposphere <br />

<br> 
with  <br>
A=aerosol type <br>
G=gas <br>
X=any component <br>

Please note that we [[Modfication of existing CF standard names|suggest changes]] for the names with '?' above and also for the medium prefix 'atmosphere' to be consistent with the general concept 'in_<medium>'.

==Odd names that do not fit in any group following the general concepts==
atmosphere_content_of_sulfate_aerosol<br />
optical_thickness_of_atmosphere_layer_due_to_aerosol? <br />
mass_concentration_of_sulfate_aerosol_in_air<br />
surface_carbon_dioxide_mole_flux

We [[Modfication of existing CF standard names|suggest changes]] to modify these names, so that they would fit in the general concepts explained here and allow for the automatic creation of individual names from groups of CF standard names. These could be added using aliases.