[CF-metadata] new standard names for atmospheric dynamics

From: Schultz, Martin <m.schultz>
Date: Mon, 19 Jan 2009 11:20:46 +0100

Dear Jonathan,

> 1) proposed standard_name: air_mass units: kg
   
   so you agree with "air_mass". Great! I don't think that the common
meteorological definition of air mass would be in conflict with this,
since we somehow assume that one grid box contains an "air mass" with
characteristic properties. Only potential problem is with astronomy ;-)
Wikipedia lists: "In astronomy, airmass is the optical path length
through Earth's atmosphere for light from a celestial source."

> 2) proposed standard_name: grid_box_volume units: m3

   cell_volume is fine with me. It would be great if one could perform a
fulltext search on the archive. Haven't found this option, and this
makes it a bit hard to find that previous discussion. Or is there
another way except downloading the archive, unzipping it and perform a
"grep..."?

> 3) proposed standard_name: grid_box_height units: m

   cell_thickness suits me just as well.

> 4) proposed standard_name: upper_tropopause_level_index units:
index

   model_level_number_at_tropopause is OK. The philosophical distinction
between the "upper" and "lower" tropopause could be done in the
cell_methods field if needed?

> 5) proposed standard_name: precipitation_formation_flux units: kg
m-2 s-1
> or:
tendency_of_precipitation_flux_due_to_formation
>
> proposed standard_name: precipitation_evaporation_flux units: kg
m-2 s-1
> or:
tendency_of_precipitation_flux_due_to_evaporation
>
> It doesn't seem quite right for it to be a tendency of precipitation
flux.
> Since the precip flux is already kg m-2 s-1, a tendency would be kg
m-2 s-2.
> Perhaps it is a tendency of the mass of precipitation, or the mass
content or
> concentration of precipitation, or maybe a vertical divergence of the
flux?

  This is difficult. In principle, "tendency_of_precipitation_mass" (or
something like it) would be right. BUT the beauty of these variables is
that they distinguish between formation and loss. OK - I just found the
"due_to_production" concept again. So, perhaps we can agree on

tendency_of_precipitation_mass_due_to_formation

and

tendency_of_precipitation_mass_due_to_evaporation

But then: have we already agreed on the sign for the latter? Did we have
a similar discussion for chemical processes already? There would be
potentially a lot of terms like
tendency_of_ozone_due_to_chemical_production or
tendency_of_ozone_due_to_chemical_loss with a similar problem. I checked
on Christiane's wiki site but couldn't find anything on this.


BTW: where are we with respect to all the new chemical names that were
proposed? It would be great if we could soon see them somehow embedded
in the standard_name table as preparations for the next IPCC runs are
ongoing and we should be prepared for that. My recommendation would be
the following:
    Add the "concept names" as given on Christiane's wiki into the
standard_name table using "X" as surrogate for the chemical species. If
a note appears at the top of the table saying that "X" is a placeholder
and must be replaced by a meaningful chemical name, then everyone should
be able to understand this. Then, add a new "compound" table
(potentially a link onto such a table on Christiane's site would do?),
where accepted entries for "X" would be listed. This still leaves the
problem that not all processes are valid for all "X", but I would judge
this as a far minor problem than the existing problem that we don't have
these names defined or that the table would pretty much explode if we
spell out all chemical standard names explicitly. Normally, we shouldn't
expect to ever receive any model output with process-species pairs that
are nonsense, as the models should only generate meaningful variables in
the first place.

Best regards,

Martin




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Received on Mon Jan 19 2009 - 03:20:46 GMT