[CF-metadata] Vertical datums (again)

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 19 Feb 2014 13:32:39 +0000

Dear Helen

Thanks for your comments.

> Whilst it is true that the specifics of the geoid used (model, degree and order of expansion etc) are important, simply being able to correctly identify 'sea surface height above reference ellipsoid' vs 'sea surface height above geoid' gives us fundamentally different parameters (first is approx = geoid height, second is dynamic topography)
> Hence even without the details of the geoid used, the very definition is extremely important

That's good to know because it is consistent with the current approach in the
CF standard name table.

> There is a significant difference in that altitude is generally applied to the height of the satellite above the reference ellipsoid - not the geoid - so I would not like to see that alias be included.

Right. That is useful to know. It is a good argument for replacing altitude
with height_above_geoid (retaining altitude as an alias for the sake of
existing data) if it could be confused with height_above_reference_ellipsoid
(which is an existing standard name).

Best wishes

Jonathan
Received on Wed Feb 19 2014 - 06:32:39 GMT