[CF-metadata] Clarifying standard names for 'mass_concentration_of_*_dry_aerosol_particles'

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 3 Jan 2018 13:40:20 +0000

Dear Daniel

> >>Is it feasible to rename all affected standard names?
> >It would be feasible (using aliases) but is it necessary? It seems to me that
> >your question has identified that there should be a distinction between e.g.
> > mass_concentration_of_particulate_X_in_air
> >and
> > mass_concentration_of_X_dry_aerosol_particles_in_air
> >for X=ammonium etc. These are different quantities: the former refers to the
> >mass of ammonium only, the latter to the dry mass of the aerosol of that type.
> >That is, we need new names for CMIP6, not aliases.
> Yes, there should be a distinction between both standard names.
> However, the latter name has been used as synonym for the first name
> up till now (e.g. in CMIP5 or in a data set I published recently).
> Additionally, the latter name has no real application - at least I
> am not aware of an application (neither for model nor for
> measurement data). Therefore, it might be reasonable for backward
> compatibility to use aliases.

I understand. That's tricky, because we've established that the second name
is a valid concept but not correct. When we use aliases, it's because we've
decided on a clearer, more consistent or more precise formulation of the
name, but in this case, it seemed that we called something an apple when
it ought to have been called an orange. We could define apple to mean orange
in future, for the sake of the existing datasets, but only if we are certain
that no-one will ever want to talk about apples.

We could just define and start using the new names, and be aware that the
CMIP5 datasets used the wrong names (because the CF process somehow made a
mistake), without defining aliases. Would that be acceptable?

Best wishes

Jonathan
Received on Wed Jan 03 2018 - 06:40:20 GMT