[CF-metadata] fixed sensors, depth, datum

From: Jonathan Gregory <j.m.gregory>
Date: Fri, 26 Sep 2008 20:15:44 +0100

Dear Ethan

> >>>- height relative to the ellipsoid
> >>>- height relative to the geoid
> I would argue against them being different quantities because there
> exist transformations between these various heights. Is that not enough
> to indicate they are the same quantity?

I don't think so, because the transformations aren't a simple matter of
convention, but involve geophysical data viz. the shape of geopotential
surfaces. If you say that height relative to ellipsoid and geoid is the
same quantity, aren't you saying that the geoid and ellipsoid are essentially
the same thing? I don't think they are the same thing; they are by definition
different from each other, and from other surfaces such as mean sea level and
"the" surface (the bottom of the atmosphere).

Best wishes

Jonathan
Received on Fri Sep 26 2008 - 13:15:44 BST