Hi Brian,
As always, I have to preface my remark with an apology for entering the
discussion late and not attempting to follow every detail. Would that some
other commitments could somehow diminish ...
Two comments:
1. on the general issue of "standard names"
There is a level of risk to the interoperability and versioning of CF
files when you introduce standard name tables. This is not a new issue in
CF, but with each new step down this path (e.g. grid_mapping_name) we
expand the problem area. GRIB stands as an example of where the need on
the part of users to add new names has fragmented the standard. For CF,
each new modeling group that develops an interesting coordinate system
will be motivated to extend the standard by encoding their own pet name
into their grid_mapping_name.
Thought should be given to how to minimize this problem. Should we
implement some kind of procedure (at Unidata?) to allow users a path to
register new grid mapping names? (Importantly registration can make users
aware that someone else may already have added the same new grid mapping
under a different name.) [Obviously, a much better solution would be if
the desired grid metrics could be generalized in a manner that does not
depend upon a name. Have all such approaches already been discussed and
dismissed as unfeasible? Aren't some of the modeling framework folks
working on this problem?]
2. on the specific example of the rotated pole grid in section 5.6
The explanatory text says "This should prevent a COARDS compliant
application from mistaking the variables rlon and rlat to be actual
longitude and latitude coordinates."
The standard names "grid_latitude" and "grid_longitude" were not a part of
COARDS, so including them does not really provide the claimed backwards
compatibility. Some word smithing to explain that the curvilinear grids
are an extension to COARDS would suffice to fix this -- there is no way
that COARDS could have understood this file.
- steve
============================
Brian Eaton wrote:
> All,
>
> I've updated the grid mappings section of the CF doc to reflect the
> consensus of the recent discussions. The current draft is CF-1.0-beta5 and
> is linked to the CF home page at
> http://www.cgd.ucar.edu/cms/eaton/cf-metadata/index.html.
>
> Please have a look and let me know what you think.
>
> Thanks,
> Brian
>
> P.S. Please feel free to comment on any aspect of the beta5 document.
> We'd love to get a non-beta version released soon.
--
| NOAA/PMEL | ph. (206) 526-6080
Steve Hankin | 7600 Sand Point Way NE | FAX (206) 526-6744
| Seattle, WA 98115-0070 | hankin at pmel.noaa.gov
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Received on Mon Mar 10 2003 - 12:41:11 GMT
