Hello,
(Apologies if this has been covered way back in the e-mail traffic, or
I've misuderstood.)
I'm a bit confused as to the use of these grid_mapping parameters with
vertical coordinates - do we need new grid_mapping_names? I'm
thinking, for example, of linking a geoid specification to a vertical
"altitude" coordinate.
Thanks,
David
---- Original message from Jonathan Gregory (12PM 11 Mar 14)
> Date: Tue, 11 Mar 2014 12:59:21 +0000
> From: Jonathan Gregory <j.m.gregory at reading.ac.uk>
> To: cf-metadata at cgd.ucar.edu
> User-Agent: Mutt/1.5.21 (2010-09-15)
> Subject: Re: [CF-metadata] Vertical datums (again)
>
> Dear Rich
>
> Thanks for keeping this going.
>
> > In CF, we have some of these parameters of the vertical coordinate
> > system specified with the "units" and "positive" attributes. And we
> > already have "add_offset" that could be used for the vertical shift.
> >
> > So that just leaves the geoid-based "Vertical Datum" or spheroid-based
> > "Datum", where the spheroid can be specified with parameters.
>
> In the agreed trac ticket 80
> https://cf-pcmdi.llnl.gov/trac/ticket/80
> we added several more attributes to grid mapping to describe reference
> surfaces in ways analogous to CRS WKT. We already have attributes to name
> and specify the reference ellipsoid (spheroid). As far as I can see, we need
> only to add an attribute of geoid_name to Appendix F to identify the geoid.
> Would that meet your requirement? Earlier discussions implied that CRS WKT
> does not have a way to name the geoid specifically.
>
> Best wishes
>
> Jonathan
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--
David Hassell
National Centre for Atmospheric Science (NCAS)
Department of Meteorology, University of Reading,
Earley Gate, PO Box 243,
Reading RG6 6BB, U.K.
Tel : +44 118 3785613
E-mail: d.c.hassell at reading.ac.uk
Received on Tue Mar 11 2014 - 08:07:21 GMT
