Hello Justin/Jonathan,
To me, the term or concept 'bathymetry' is the spatial variation of seafloor depth and should only be applied to a grouping of depth measurements with associated co-ordinate variables and not to just a depth parameter.
Cheers, Roy.
-----Original Message-----
From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
Sent: 14 April 2011 09:33
To: Justin R. Davis
Cc: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] Proposal for new standard names: depth/bathy/topo rel to datum
Dear Justin
> sea_floor_depth_below_reference_datum (positive down)
looks fine to me.
Isn't this the same thing:
> bathymetry_below_reference_datum (postive down)
"bathymetry" means sea-floor depth, doesn't it?
For consistency with other stdnames, in particular
height_above_reference_ellipsoid
sea_surface_height_above_reference_ellipsoid
this one
> topography_above_reference_datum (postive up)
should be
surface_height_above_reference_datum
I think.
> Furthermore, I'd also propose that any of these 3 would be required
> to have metadata with them (e.g. NetCDF attribute) which
> specifically defines the reference datum. This metadata would be
> called "VerticalDatum" (IOOS uses this) and would have a syntax like
> the following for NAVD88:
> urn:ogc:def:datum:epsg::5103
We did talk quite a lot about this when Phil Bentley proposed the extensions
which we adopted for grid_mapping to describe the ellipsoid etc. The discussion
stalled because we didn't really understand what "vertical datum" means! As
you and I have been discussing separately, if NAVD88 is a geoid, I think we
should call it a geoid in the standard name, and we should extend grid_mapping
so it can identify the geoid by name, perhaps also giving a URN as you say.
Unlike the ref ellipsoid, the geoid cannot be specified by metadata, as it's
too complicated!
best wishes
Jonathan
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Received on Thu Apr 14 2011 - 08:55:08 BST
