[CF-metadata] CF Specification of Vertical Datums

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 13 Apr 2011 15:32:47 -0000

Dear Justin

> Specifically, I'm trying to make sure that its clear that the "z"
> (bathy/topo) and "eta" (water level) are being expressed relative to
> either NGVD29 or NAVD88...currently the "CF Standard Names" for
> "sea_surface_height*" mention only mean water level, geoid or
> ellipsoid...none of which are really the same as NGVD29/NAVD88...and
> the "depth" standard name has no other variants which look
> appropriate.
>
> Previous discussion on this topic include approaches of creating a
> new standard names (e.g.
> water_surface_height_above_reference_datum)

I think that is the correct approach for the standard name, and if you have
a need for it now, please propose such names. Of course, the above leaves the
the reference surface unspecified. I would argue that if the reference surface
has a geophysical meaning, it should be identified in the standard name e.g.
  water_surface_height_above_mean_high_water
What sort of surface is NAVD88, if not an ellipsoid or a geoid? (Excuse my
ignorance - I am not a geodesist).

Best wishes

Jonathan
Received on Wed Apr 13 2011 - 09:32:47 BST