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

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Vincent-Henri PEUCH - replies by Christiane Textor (CT)

Thank you for this work! A few minor comments/suggestions/questions :
  • 1) "nitrogen_monooxide" -> "nitrogen monoxide"?
(CT) both names are allowed by IUPAC, and I chose the monooxid-version to be consistent with dioxid - but I change it.
  • 2) 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?
(CT) good idea, I changed it.
  • We have also to chose :
- if only the species with the name listed go in the sum
- or if it is up to the modeller to select all nitrogen oxides in his/her chemical scheme.
(CT) would go for the second option. Included in the comment/explanation.
The explanation is "includes all nitrogen oxides included in the model, to be specified in by the modeller in the long_name attribute if possible ???" I doubt however, that this is CF conform, as long_names are not part of CF...

  • 3) 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) "troposphere_content" (as in e.g. "troposphere_content_of_formaldehyde_in_air") does indeed mean vertical integral in the troposphere only, in contrast to e.g. "atmosphere_sulfate_content" which is commented in the CF conventions as follows: "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."
(CT)I agree that the troposphere needs to be defined. The 150ppb O3 isosurface is a good measure for atmospheric chemsitry problems and has been used in ACCENT/PHOTOCOMP. I explain my ideas below.
  • 4) 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) Dobson units are not possible within the concept of CF which is based on UDUNITS, see also the discussion on units

  • 5) 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?
(CT) I ask this question to the GEMS-GRG and HTAP communities
  • 6) add "mole_fraction_of_lead_in_air". Lead is the radioactive daughter of Radon, with wet scavenging as principal sink. There are some observations and it is useful to evaluate models, as decided in GRG+VAL.
(CT) done

Christiane Textor: Tropopause definition

  • Several tropopause definitions exist:
- 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
For chemical purposes it seems appropriate to define up_to_chemical_tropopause with the explanation from the surface up to chemical tropopause (150 ppb O3 isosurface).