Lars,
Good catch! It seems that history may need to be an exception to such a
rule. A comment attribute should also probably be considered to be an
exception as well. Or the concept needs refinement.
Jim
On 3/15/19 8:48 AM, Bärring Lars wrote:
Dear all,
I have come across many CMIP5 files that have the same attribute
[name] attached to the data variable as found in the globals.
In particular it seems that CMOR was writing variable processing
history attached to the variable, and more general file processing in
the global history.
I have also seen that "comment" sometimes occur both as global and as
variable attribute.
If such a duplication occurs, CF writes:
"When an attribute appears both globally and as a variable attribute,
the variable’s version has precedence."
My interpretation of this is that if there are contradictory
information then the variable's attribute has precedence, but
otherwise it does not invalidate or overshadows what is in the global
attribute.
However, the data model presented in the GMD paper
(https://www.geosci-model-dev.net/10/4619/2017/ page 4629, [page 11],
under "4.1 The field construct") presents a more restrictive
interpretation:
"In the data model, we consider that netCDF global file attributes
apply to every data variable in the file, except where they are
superseded by netCDF data variable attributes with the same name."
I understand this to mean that if the same attributes (e.g. comment or
history) is present both as global and variable attribute, then the
global attribute is overshadowed (as if it did not exist at all)?
Is this correct? If so, is this the best solution?
Would not concatenating the information contained in each (putting the
variable text first) be a more appropriate way to resolve the
situation (and thus specify in the data model)?
Kind regards,
Lars
--
Lars Bärring
FDr, Forskare
PhD, Research Scientist
SMHI / Swedish Meteorological and Hydrological Institute
Rossby Centre
SE - 601 76 NORRKÖPING
http://www.smhi.se <http://www.smhi.se/>
E-post / Email:lars.barr...@smhi.se <mailto:lars.barr...@smhi.se>
Tel / Phone: +46 (0)11 495 8604
Fax: +46 (0)11 495 8001
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