I meant to post the following message to the list, as well as the individual recipients.
> -----Original Message----- > From: Pamment, Alison (STFC,RAL,RALSP) > Sent: 20 January 2016 12:23 > To: 'Jonathan Gregory' > Cc: [email protected]; [email protected] > bremen.de; [email protected]; Bennett, Victoria (STFC,RAL,RALSP) > Subject: RE: [CF-metadata] New standard names for ESA GHG CCI quantities > > Dear Jonathan, > > I agree that we don't usually combine "atmosphere" and "in_air" in the > same name. My reason for doing it in this case was because the original > proposal specified two conditions: > 1) dry air; > 2) column average quantity (therefore not local). > I needed to find some way of including both in the name. However, it may > be that we don't need the "dry" bit at all, in which case we could just go > with atmosphere_mole_fraction_of_methane and > atmosphere_mole_fraction_of_carbon_dioxide, and there is no problem. If > it really is important that we specify "dry" for these quantities, perhaps a > better solution would be to put it at the start of the name, thus, > dry_atmosphere_mole_fraction_of_methane and > dry_atmosphere_mole_fraction_of_carbon_dioxide. Does that look better? > > Best wishes, > Alison > > > -----Original Message----- > > From: CF-metadata [mailto:[email protected]] On > Behalf > > Of Jonathan Gregory > > Sent: 19 January 2016 16:55 > > To: [email protected] > > Subject: [CF-metadata] New standard names for ESA GHG CCI quantities > > > > Dear Alison > > > > In existing names we generally use "atmosphere" to indicate a property of > > the > > atmosphere as a whole (or a large portion of it) and "in_air" to indicate a > > local property within the atmosphere. We don't use both phrases at once. > > These > > quantities can be regarded as means of local properties, I think, so just > > in_air would be sufficient. If no vertical coordinate is specified, it > > should > > apply to the entire atmosphere, but to make that clear a cell_method > could > > be > > added to record that it's a vertical mean. > > > > Best wishes > > > > Jonathan > > > > ----- Forwarded message from [email protected] ----- > > > > > Date: Tue, 19 Jan 2016 16:39:38 +0000 > > > From: [email protected] > > > To: [email protected] > > > CC: [email protected], [email protected], > > > [email protected], > > > [email protected] > > > Subject: [CF-metadata] New standard names for ESA GHG CCI quantities > > > > > > Dear All, > > > > > > I have been asked to re-propose two standard names that were > originally > > proposed by Maximilian Reuter in 2014 but which did not receive any > > comments at the time: http://mailman.cgd.ucar.edu/pipermail/cf- > > metadata/2014/057373.html. > > > > > > I have rephrased the original proposal to make the names more CF like > > and have added some standard definition text, so the names are now > > proposed as follows: > > > atmosphere_mole_fraction_of_methane_in_dry_air (canonical units: 1) > > > 'Mole fraction is used in the construction "mole_fraction_of_X_in_Y", > > where X is a material constituent of Y. A chemical species denoted by X > may > > be described by a single term such as "nitrogen" or a phrase such as > > "nox_expressed_as_nitrogen". The "atmosphere mole fraction" of a > > quantity refers to the column average from the surface to the top of the > > atmosphere. Methane is a member of the group of hydrocarbons known as > > alkanes. There are standard names for the alkane group as well as for > some > > of the individual species. The chemical formula for methane is CH4.' > > > > > > atmosphere_mole_fraction_of_carbon_dioxide_in_dry_air (canonical > > units: 1) > > > 'Mole fraction is used in the construction "mole_fraction_of_X_in_Y", > > where X is a material constituent of Y. A chemical species denoted by X > may > > be described by a single term such as "nitrogen" or a phrase such as > > "nox_expressed_as_nitrogen". The "atmosphere mole fraction" of a > > quantity refers to the column average from the surface to the top of the > > atmosphere. The chemical formula for carbon dioxide is CO2.' > > > > > > These names reflect the original proposal, and generally follow the > syntax > > of existing names such as mole_fraction_of_carbon_dioxide_in_air. I have > > prepended these names with the word "atmosphere" as a way of > indicating > > a column amount, similar to existing atmosphere_mass_content names. > > > > > > We don't currently have any "dry_air" names in CF. When this topic last > > came up on the mailing list (as far back as 2008 under the thread entitled > > "mixing ratio") it was concluded that the current "in_air" names don't tie > the > > definition down to either dry or ambient air. The reason for this > (deliberate) > > vagueness is that numerically the quantities in dry or moist air are not > > very > > different except in the case of water vapour itself where we define > > humidity_mixing_ratio to mean " ratio of the mass of water vapor to the > > mass of dry air". The gist of the 2008 conversation was that if we ever > > needed to be very precise about making the distinction between ambient > > air and dry air then we would be able to introduce appropriate names at a > > later stage, but there wasn't a pressing need at the time. An offline > > conversation I had more recently with Jonathan Gregory and Martin > Schultz > > went along similar lines, basically saying that we wouldn't change any > > existing names where the deliberate impre > > ci > > > sion isn't important, but reiterating that we could introduce new names > if > > there are cases where it does matter, specifying dry or ambient. > > > > > > Please could Maximilan, Veronica or another member of the CCI team > > answer the question about whether there is a real need to specify > "dry_air" > > in the case of these names, or can we get away with being a bit more > vague? > > If vagueness is OK, then the names would simplify to > > atmosphere_mole_fraction_of_methane_in_dry_air and > > atmosphere_mole_fraction_of_carbon_dioxide. Also, do others agree > with > > my using "atmosphere" here to indicate the column average? All > comments > > are welcome. > > > > > > Best wishes, > > > Alison > > > _______________________________________________ > > > CF-metadata mailing list > > > [email protected] > > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > > ----- End forwarded message ----- > > _______________________________________________ > > CF-metadata mailing list > > [email protected] > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
