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[CF-metadata] Same parameter, different meaning (pressure)

From: Roy Lowry <rkl>
Date: Thu, 28 Aug 2008 14:00:31 +0100

Hello Jonathan/John,

Mounting specification in other metadata is fine by me: it's where I'd be without a 25 year legacy system millstone. Can someone recommend a way this should be done in a CF file so that it can be adopted by Nan et al.?

To answer John's question. I agonised over that point - should I class the pressure on a 'semi-fixed' moored instrument with profilers et al. (i.e. z co-ordinate and nothing else)? In the end I decided no because there are circumstances where usable tidal information (e.g. in low-current regimes where knock-down doesn't happen) can be derived from the semi-fixed moored instrument, which can never be the case for a profiler.

Cheers, Roy.

>>> John Graybeal <graybeal at mbari.org> 08/28/08 1:29 PM >>>
Jonathan,

yes, now we're talking. I wanted to be sure that case was covered, as
most mounting are likely to be above the sea floor, and some may be a
known GPS-style altitude but uncertain distance above the sea floor.
The latter case is also met by the coordinate variable.

But as Roy says, we still haven't differentiate mountings. My
question for Roy is, do we differentiate mounting between pressure on
an AUV, tow-yo, or vertical profiler, and pressure on a buoy? To be
consistent we should either *always* make it possible to differentiate
mountings (and similar things affecting the interpretation of data) in
the standard name, or we should recognize that mounting
characteristics are explicitly not described by the standard name. I
prefer the latter.

John



On Aug 28, 2008, at 4:44 AM, Jonathan Gregory wrote:

> Dear Roy
>
> If the sensor is 200 m above the sea-floor, its standard name should
> be
> sea_water_pressure, not sea_water_pressure_at_sea_floor. It would
> need a
> coordinate variable or scalar coordinate variable with a value of
> 200 m and a
> standard name of height_above_sea_floor (which is an existing
> standard name).
>
> Does that make sense? Best wishes
>
> Jonathan

On Aug 28, 2008, at 4:13 AM, Roy Lowry wrote:

> Hello Jonathan,
>
> However, we still haven't solved Nan's problem of differentiating
> between fixed and tethered sensors 200m above the seabed. This is
> important because the former is a reliable measure of sea level but
> the latter isn't.

--------------
John Graybeal <mailto:graybeal at mbari.org> -- 831-775-1956
Monterey Bay Aquarium Research Institute
Marine Metadata Interoperability Project: http://marinemetadata.org



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Received on Thu Aug 28 2008 - 07:00:31 BST

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