Hi Martin,

I see your point.  The tendency definition certainly argues for negative
values for sedimentation and a change of "Loss to sediments" to something
like "Tendency with respect to sedimentation" for consistency.

Cheers, John

On Wed, Sep 5, 2018 at 5:05 AM, Martin Juckes - UKRI STFC <
[email protected]> wrote:

> Hello All,
>
>
> there is a problem with the way 4 CMIP6 variables use standard names
> defined for tendencies due to sedimentation. Sedimentation in CF means
> sedimentation in water, so sedimentation of a substance always leads to a
> negative tendency of the amount of that substance suspended in the ocean.
> In CMIP6, following CMIP5 usage, standard names for tendencies of amounts
> of substances in the ocean have been used for variables with long names
> which imply that they are negative tendencies, i.e. loss rates. E.g.
>
> - frfe "Iron Loss to Sediments"  tendency_of_ocean_mole_
> content_of_iron_due_to_sedimentation.
>
>
> We recently dealt with a similar issue for atmospheric deposition rates:
> http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2018/020204.html and
> the solution (http://cfeditor.ceda.ac.uk/proposal/3225 ) was to introduce
> new standard names of the form "minus_tendency_...".
>
>
> For the four ocean variables (frfe, frn, fric, froc) I propose 4 new
> standard names:
>
>  minus_tendency_of_ocean_mole_content_of_inorganic_carbon_
> due_to_sedimentation
>  minus_tendency_of_ocean_mole_content_of_organic_carbon_due_
> to_sedimentation
> minus_tendency_of_ocean_mole_content_of_iron_due_to_sedimentation (as in
> CMIP5)
> minus_tendency_of_ocean_mole_content_of_elemental_nitrogen_
> due_to_denitrification_and_sedimentation
>
>
> These all correspond to minus one times the quantity defined by existing
> standard names.
>
>
> More details about the 4 CMIP variables are given on the Data Request
> github site: https://github.com/cmip6dr/CMIP6_DataRequest_
> VariableDefinitions/issues/344
>
>
> regards,
>
> Martin
>
> <http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2018/020204.html>
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