Dear Jonathan,
Sorry, it looks like I've misunderstood the meaning of "WGS84".
Previously I have only ever seen the term "WGS84" as meaning a
reference ellipsoid, but it looks like the WGS84 is really a geoid,
which is based upon that reference ellipsoid. So you are quite right.
So in Dale's case, "depth_below_geoid" would seem appropriate. Is
there a way of saying which geoid is meant?
Regards, Jon
On Wed, Sep 10, 2008 at 3:37 PM, Jonathan Gregory
<j.m.gregory at reading.ac.uk> wrote:
> Dear Jon
>
> As I've said, I'm pretty ignorant on this, but I had thought on reading e.g.
> wikipedia that WGS84 must include a more detailed geoid as well as a reference
> ellipsoid. Is it not the case these two can different by large amounts locally
> owing to the bumps in the gravity field? If so, I would have thought that
> measurements like these might relate to the geoid (which is much more like
> sea level) than the ellipsoid. What have I misunderstood?
>
> Best wishes
>
> Jonathan
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--
Dr Jon Blower
Technical Director, Reading e-Science Centre
Environmental Systems Science Centre
University of Reading
Harry Pitt Building, 3 Earley Gate
Reading RG6 6AL. UK
Tel: +44 (0)118 378 5213
Fax: +44 (0)118 378 6413
j.d.blower at reading.ac.uk
http://www.nerc-essc.ac.uk/People/Staff/Blower_J.htm
Received on Thu Sep 11 2008 - 01:28:19 BST
