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[CF-metadata] Reference for GRIDSPEC?

From: Chris Barker <chris.barker>
Date: Thu, 10 Dec 2015 15:46:15 -0800

On Thu, Dec 10, 2015 at 8:19 AM, Jonathan Gregory <j.m.gregory at reading.ac.uk
> wrote:

> After that proposal was agreed, we had some further discussions concerning
> the
> relationship of gridspec and ugrid and how they could be made more similar.
>

I remember that conversation, though I never took the time to look at
gridspec.

For reference, here is the current UGRID spec:

https://github.com/ugrid-conventions/ugrid-conventions/blob/master/ugrid-conventions.md

I just looked at:

http://www.gfdl.noaa.gov/~vb/gridstd/gridstdse3.html#x5-240003.4

And my first impression is that while it is handling the same information
as UGRID, it's pretty different, at least with respect to variable names.
My impression is thus:

gridspec was developed to support a certain set of (structured) grids. The
unstructured bit was then added to well-match the model and conventions
that had been established.

UGRID, n the other other hand was built from scratch, based on CF and the
vocabulary and conventions that unstructured grid (oceanographic) modelers
use. So it's a more wordy, but actually matched pretty well with what
FVCOM, ADCIRC, SELFE, etc already put out.

So: I don't think that we in the UGRID community are going to want to turn
what we'be got on end to match gridspec. I suspect the gridspec community
is in the same position. Thugh: how much is gridspec used for unstructured
grids? If not much then maybe just drop that support, and use UGRID.

HOWEVER: I haven't looked closely enough -- maybe the differences really
are just vocabulary -- so maybe we could unify them if we allow multiple
names for the same thing. i.e, in a triangular mesh grid, you specify
either:


var_name:cf_role = "face_node_connectivity" ;

or

var_name:standard_name = "neighbor_cell_index"

though, honestly, gridspec doesn't look very CF-y to me anyway :-)


-CHB



-- 
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R            (206) 526-6959   voice
7600 Sand Point Way NE   (206) 526-6329   fax
Seattle, WA  98115       (206) 526-6317   main reception
Chris.Barker at noaa.gov
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