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
>
>
Received on Wed May 16 2018 - 05:58:05 BST
