Dear Jonathan,
Of the options you suggest, I think "minus_tendency_" is the neatest, being more compact that "minus_one_times_tendency_" without, as far as I can see, introducing any ambiguity.
I had a look on-line for antonyms of tendency, and discovered that our usage of "tendency" as an abbreviation for "derivative wrt time" is too specialised to appear in any of the online dictionaries which I could find. I interpret this as supporting your view that a construction with minus is safer that trying to look for alternative words,
regards,
Martin
________________________________
From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of Jonathan Gregory <j.m.gregory at reading.ac.uk>
Sent: 16 May 2018 18:24
To: cf-metadata at cgd.ucar.edu
Subject: [CF-metadata] Dry and wet deposition rates
Dear Martin
I would favour minus_one_times_tendency. This is clumsy but it is very clear,
I think, and as you say it's already in use for other such awkward situations.
I feel that if we replace the word tendency (as in 2) or use a different idea
altogether (as in 3) there will not be such an obvious relationship between the
names of opposite sign i.e. tendency_of_X and minus_one_times_tendency_of_X
and this is a strong advantage, I feel.
I wonder whether we could reduce the clumsiness by saying e.g. minus_tendency,
negated_tendency or negative_tendency, but I'm not sure these are as clear as
minus_one_times_tendency. I think they might all give rise to questions. Of
those, I think minus_tendency would be best.
Other more exotic alternatives could be to invent a new word e.g. antitendency,
or to allow a - sign in the standard name: -tendency_of_X!
Best wishes
Jonathan
----- Forwarded message from Martin Juckes - UKRI STFC <martin.juckes at stfc.ac.uk> -----
> Date: Wed, 16 May 2018 11:58:05 +0000
> From: Martin Juckes - UKRI STFC <martin.juckes at stfc.ac.uk>
> To: "cf-metadata at cgd.ucar.edu" <cf-metadata at cgd.ucar.edu>, Michael Schulz
> <michaels at met.no>, Taylor Karl <taylor13 at llnl.gov>
> Subject: [CF-metadata] Dry and wet deposition rates
>
> There are 20 variables in the CMIP6 data request for a variety of dry and wet deposition rates. Many of these variables have been used in CMIP5 and earlier with standard names of the form: tendency_of_atmosphere_mass_content_of_dust_dry_aerosol_particles_due_to_dry_deposition.
>
>
> However, there is a conflict in the intended sign convention. The deposition rates should be positive when material is leaving the atmosphere, but the standard names that have been used should be positive when the atmospheric content is increasing. To resolve this we need a set of new standard names. The existing tendency names are:
>
> tendency_of_atmosphere_mass_content_of_dust_dry_aerosol_particles_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_ammonia_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_ammonium_dry_aerosol_particles_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_aerosol_particles_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_sulfur_dioxide_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_particles_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_nitrogen_compounds_expressed_as_nitrogen_due_to_deposition
> tendency_of_atmosphere_mass_content_of_dust_dry_aerosol_particles_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_ammonia_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_ammonium_dry_aerosol_particles_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_noy_expressed_as_nitrogen_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_sulfur_dioxide_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_particles_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_particulate_organic_matter_dry_aerosol_particles_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_ozone_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_seasalt_dry_aerosol_particles_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_wet_deposition
> tendency_of_atmosphere_mass_content_of_seasalt_dry_aerosol_particles_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_noy_expressed_as_nitrogen_due_to_dry_deposition
> tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_dry_deposition
>
> Three options have been raised in the preliminary discussions:
> (1) Prefix each name with "minus_one_times_": this construction is already used for 3 names.
>
> (2) Replace "tendency_of_" with "depletion_rate_of_": this is a new construction, but is structurally close to what we have and makes the relation between variables very clear;
>
> (3) Replace "tendency_of_atmosphere_mass_content_of_" with "surface_downward_mass_flux_of_": this uses an existing construction already used in 8 standard names.
>
> What do others on the list think?
>
> regards,
> Martin
>
>
>
>
> ________________________________
> From: Juckes, Martin (STFC,RAL,RALSP)
> Sent: 16 May 2018 08:14
> To: Michael Schulz; Taylor Karl
> Cc: larry.horowitz at noaa.gov; mark.webb at metoffice.gov.uk; Bodas-Salcedo, Alejandro; Pamment, Alison (STFC,RAL,RALSP)
> Subject: Re: Conflicting sign conventions in deposition rates
>
>
> Hello Michael, Karl,
>
>
> OK, it sounds as though we should keep the variables as they are, i.e. positive for deposition from the atmosphere, and fix the standard names.
>
>
> I don't think a positive attribute will solve this problem. It may be useful to add "positive=down", but it still leaves an inconsistency with the standard names which definitely should be used with positive "up". Standard names for variables with an opposite sign convention would not be synonyms: there are many examples of pairs of names which differ only in the sign convention, e.g.
>
> surface_upwelling_shortwave_flux_in_air -- minus_one_times_surface_upwelling_shortwave_flux_in_air (+ 2 other pairs like this);
>
> surface_downward_heat_flux_in_air -- surface_upward_heat_flux_in_air (+ 5 other pairs like this).
>
>
> We can construct standard names for minus the tendency of quantities in several ways, but it may be better to have that discussion on the CF discussions email list .. so I'll make a proposal there, also raising Karl's suggestion (depletion_rate_of_ ....),
>
>
> regards,
>
> Martin
>
>
>
>
>
>
> ________________________________
> From: Michael Schulz <michaels at met.no>
> Sent: 15 May 2018 19:46
> To: Juckes, Martin (STFC,RAL,RALSP)
> Cc: Taylor Karl; larry.horowitz at noaa.gov; mark.webb at metoffice.gov.uk; Bodas-Salcedo, Alejandro; Pamment, Alison (STFC,RAL,RALSP)
> Subject: Re: Conflicting sign conventions in deposition rates
>
> Hi,
>
> true - tendencies have not carefully chosen with a sign in mind.
>
> There is very long tradition that these variables are ?positive". So that should not be changed.
>
> The standard names are also used since quite some time.
>
> Adding a positive attribute would be my preferred solution.
>
> Otherwise ?surface_downward_mass_flux_of_? is fine for me as well. But that would introduce a synonym in the system, right?
>
> best wishes
> Michael
>
>
>
>
>
> > On 15 May 2018, at 20:13, Martin Juckes - UKRI STFC <martin.juckes at stfc.ac.uk> wrote:
> >
> > Hello All,
> >
> >
> > Larry has pointed out a conflict between variable long names and standard names for a set of deposition rate variables, many of which were in the CMIP5 aero table, e.g. wetso4, "Wet Deposition Rate of SO4" with standard name tendency_of_atmosphere_mass_content_of_sulfate_expressed_as_sulfur_dry_aerosol_due_to_wet_deposition
> >
> >
> > A deposition rate would normally be positive when material is leaving the atmosphere, making the tendency of atmosphere mass content negative.
> >
> >
> > I will try to check the sign convention adopted by people submitting data for CMIP5, but I suspect that we should follow the sign convention implied by the long name .. but this would require new standard names for these variables. A full list of the variables is here: https://github.com/cmip6dr/CMIP6_DataRequest_VariableDefinitions/issues/328
> >
> >
> > For new standard names, we could either use the "minus_one_times_" construction, or replace "tendency_of_atmosphere_mass_content_of_" with "surface_downward_mass_flux_of_".
> >
> >
> > What do others think?
> >
> >
> >
> > regards,
> >
> > Martin
> >
> >
>
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