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-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Jonathan Gregory Sent: 14 April 2011 09:33 To: Justin R. Davis Cc: cf-metadata@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 _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- This message (and any attachments) is for the recipient only. NERC is subject to the Freedom of Information Act 2000 and the contents of this email and any reply you make may be disclosed by NERC unless it is exempt from release under the Act. Any material supplied to NERC may be stored in an electronic records management system. _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata