Dear Jonathan,
>> Since CF is expanding to include in situ data, can we express this
>> somehow, so that users know that the coordinate value depends on
>> certain assumptions?
>
> Yes, we could, but I would not make that distinction in the standard name,
I agree that this shouldn't be expressed in the standard name - I
guess this was a little off-topic for this thread and probably merits
a separate conversation.
Cheers, Jon
On Mon, Sep 29, 2008 at 11:33 AM, Jonathan Gregory
<j.m.gregory at reading.ac.uk> wrote:
> Dear Jon
>
>> - Being pedantic, two points at the same height above the geoid might
>> not have quite the same potential energy. The 3D geopotential
>> contours are not everywhere equally-spaced. However, I imagine this
>> is not usually a large effect, unless the data in question are close
>> to a large gravity anomaly.
>
> If I understand you, then I agree. That is because geopotential is not the
> same as gravitational potential, so height above a gravitational equipotential
> surface is not the same as height above geoid. These again are two distinct
> physical quantities.
>
>> - Vertical coordinate values (heights, altitudes etc) are often
>> inferred from other quantities (esp. pressure in both air and water).
>> Since CF is expanding to include in situ data, can we express this
>> somehow, so that users know that the coordinate value depends on
>> certain assumptions?
>
> Yes, we could, but I would not make that distinction in the standard name, if
> the intention is just to supply some extra information about how the quantity
> was obtained. That does not make different kinds of quantity. On the other
> hand, if the quantities are regarded as distinct, so that you might have
> several of them in the same dataset, and wanted to compare them with the
> corresponding ones in another dataset, perhaps an argument could be made
> for distinguishing them by standard name. However, another attribute might
> still be a better way, I suspect. We would need some use-cases to discuss
> this when it arises.
>
> Cheers
>
> 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 Mon Sep 29 2008 - 04:39:08 BST
