[CF-metadata] Proposal for new standard names: depth/bathy/topo rel to datum

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 14 Apr 2011 08:33:04 -0000

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
Received on Thu Apr 14 2011 - 02:33:04 BST