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[CF-metadata] water level with/without datum

From: Jeff deLaBeaujardiere <Jeff.deLaBeaujardiere>
Date: Tue, 23 Feb 2010 09:11:24 -0500

Dear CF group:

Thank you for your time in discussing this matter.

I would counsel you *not* to make wholesale changes to existing names just because IOOS needs names for water levels that may or may not be measured in the ocean! Replacing 'sea_' with something else seems like it would break much existing code. Adding some names should be mostly harmless.


For the specific case of water-level measurement devices, I think the term water_level_* is better, applied generically regardless of oceanic, lacustrine or riverine environment, for the following reasons.

* There is no other generic name, and inventing one like SLR or sea+lake+river seems contrived.

* Every use of sea_level I can find in the CF name list refers to sea level as a semi-constant reference point rather than as an instantaneous measurement. Indeed, a comment used repeatedly in the CF table is that "sea_level means mean sea level, which is close to the geoid in sea areas." Therefore, separate names for sea_level_*, lake_level_ and river_level_* do not seem appropriate.

* Yes, there is water in the atmosphere and underground. CF already seems to qualify those uses with terms like 'atmosphere', 'cloud' and 'in air.' Therefore, it does not seem necessary to qualify 'water' as being on the surface--simply retain the existing non-surface qualifiers. If you later need a name to refer to the level of water in an underground aquifer or something, then create one.


Regarding the Use Case of measuring temperature in the sea and then continuing the trajectory upriver: there currently do not exist water_temperature names other than sea_water_temperature, so the Use Case is not satisfied at present. Perhaps in future CF could define additional generic names like water_temperature that may have specializations such as sea_water_temperature and fresh_water_temperature, but this can be done later and independently of the existing actual use case of water level measurements.

Cheers,
Jeff DLB

-- 
Jeff de La Beaujardi?re, PhD
Senior Systems Architect, Data Integration Framework
Integrated Ocean Observing System (IOOS) Program Office
National Oceanic and Atmospheric Administration
1100 Wayne Ave #1225, Silver Spring MD 20910 USA
+1 301 427 2427
Jeff.deLaBeaujardiere at noaa.gov 
Received on Tue Feb 23 2010 - 07:11:24 GMT

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