[CF-metadata] Fwd: standard name proposal for CCMVal

[Martin Juckes]

Attached is a list of around 150 proposed standard names needed for the CCMVal 
project.

CCMVal is the Chemistry Climate Model Validation exercise 
(http://www.pa.op.dlr.de/CCMVal/).

The coupled chemistry-climate model data for the validation will be hosted by 
BADC, and the intention is that it should be CF compliant netcdf. In order to 
achieve this we need standard names fro around 150 quantities not yet covered 
in the standard name table. The proposed new names are listed in the attached 
word document, split into 4 tables.

There has been some preliminary discussion, with the most controversy caused 
by the `age_of_stratospheric_air'. 

A couple of key quotes from the discussion between Darryn Waugh and Jonathan 
Gregory are given below. No real agreement was reached, so the decision is up 
to other members of the list.

QUOTE from Darryn Waugh
The age of stratospheric air is the time since last contact with the 
troposphere (just as age in the ocean is time since contact with atmosphere). 
There is a distribution of ages (i.e. not a single travel time) but we are 
concerned here with the mean of the times, hence the need for "mean age".   
It is not a residence time, and the use of "mean" is crucial.    

The term "mean age" is extensively used in stratospheric, oceanic, and 
groundwater communities (with "of water" added for latter two), so I think 
this counts as interdisciplinary, and again I am lost at the resistance to 
it.
END QUOTE
QUOTE from Jonathan Gregory
I agree that "mean" is needed, but I think that in CF metadata it belongs in
the cell_methods rather than in the standard_name.
END QUOTE

There was also substantial discussion between Jonathan and myself about the 
use of "_burden" to indicate a whole atmosphere integral. Jonathan favoured 
something of the form "area_integral_of......_content", but conceded that the 
area integral of a vertical integral was not the most natural of 
formulations. The term "burden" is widely used in the scientific literature 
with the meaning intended here.

The original list from the CCMVal community included a number of annual loss 
variables, but these have been replaced with tendencies, the intention being 
to use the cell_methods attributes to express annual losses as summed 
tendencies.

The gravity wave terms also caused some comment. E.g.
 upward_flux_of_eastward_momentum_due_to_nonorographic_eastward_gravity_waves

eastward_momentum indicates the component of the momentum which is being 
transported, eastward_gravity_waves indicates the class of gravity waves 
included, with eastward referring to the phase speed of the waves. There is 
thus no obvious redundancy here, though there is a tendency in the specialist 
community to do away with one "eastward" when referring to this quantity, 
since gravity waves with eastward phase speeds only carry eastward momentum. 
I have submitted the longer version, as this level of knowledge should 
probably not be expected of standad name interpreters.

Names such as the "dynamic_tropopause_potential_temperature" introduce the 
problem that the precise definition of the dynamic tropopause is not fixed. 
The intention is to use an attribute in the file to give a reasonably precise 
definition. The method will be used for "..middle_atmosphere_  ..._burden",
which requires a specification of the definition used for "middle atmosphere".
After discussion with Jonathan it was decided, however, that there was no need 
to get the method for doing this into CF at this time.

sincerely,
Martin Juckes


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