[Go-essp-tech] CMOR and cell_measures issues

[martin.juckes at stfc.ac.uk]

Hello Karl,

 

Thanks for clearing this up,

 

Martin

 

From: Karl Taylor [mailto:taylor13 at llnl.gov] 
Sent: 19 October 2010 18:36
To: Juckes, Martin (STFC,RAL,SSTD)
Cc: philip.bentley at metoffice.gov.uk; Doutriaux, Charles;
jamie.kettleborough at metoffice.gov.uk; Lawrence, Bryan (STFC,RAL,SSTD);
cmor at lists.llnl.gov; go-essp-tech at ucar.edu; Kyle.Olivo at noaa.gov
Subject: CMOR and cell_measures issues

 

Dear CMOR users,

It has been brought to our attention that the CF checker (which is
different from the CMOR checker) traps an error in CMOR-produced files
indicating non-compliance with the CF conventions.  The error is that
the cell_measures attribute is defined, but the area and/or volume data
is not contained in the file.  [We have included a non-CF attribute
called "associated_files" that points to the files containing
area/volume.]  Still, in order to not confuse CF-compliant software we
plan to immediately release a new version of CMOR in which the
"cell_measures" attribute is replaced by a non-CF attribute named
"ext_cell_measures" (indicating that the area/volume data is externally
available).

Also, some groups have reported that not all their variables are carried
on the same grid.  (For example, sometimes the u and v fields are
staggered relative to T.)  In this case it would be necessary to have
more than one set of areas associated with the model, and this is not
currently possible since only areacella, areacello, and volcello are
defined in the CMIP5 request for model output.  We have therefore
decided to include an option for CMOR users to suppress writing of the
ext_cell_measures attribute when it would point to areacella or
areacello incorrectly.  The user would in effect be allowed one set of
areas to be associated with the atmospheric model and one set of
areas/volumes to be associated with the ocean models.  The user would
suppress the ext_cell_measures attribute (and areacella, areacello,
volcello would not appear in the "associated_files" attribute) for any
variables where these areas/volumes would be incorrect.

We hope this is acceptable.

Best regards,
Karl and Charles




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