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, B?rring 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 superseded by netCDF data variable attributes with the same name."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 B?rring
> FDr, Forskare
> PhD, Research Scientist
> SMHI? /? Swedish Meteorological and Hydrological Institute
> Rossby Centre
> SE - 601 76 NORRK?PING
> http://www.smhi.se <http://www.smhi.se/>
> E-post / Email:lars.barring at smhi.se <mailto:lars.barring at smhi.se>
> Tel / Phone: +46 (0)11 495 8604
> Fax: +46 (0)11 495 8001
> Bes?ksadress / Visiting address: Folkborgsv?gen 17
>
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