[cf-pointobsconvention] Draft 2

[John Graybeal]

I'm not Don, but... I agree that names are necessary and more 
reasonable (i.e., with both your points).  I just don't think 
making them part of the standard name scales *in an observing 
framework*.  The key point here is that I know what an instrument 
(think 1000s of instruments in an observing system) can measure, 
and I'm going to move the instrument to different places, and I 
don't want to change the name of the measurement -- even the 
standard name -- as the instruments move around.  The 
post-processors and modellers can do that if they want, but 
for operational concerns it is an inappropriate linkage.

John

At 6:37 PM +0100 9/18/07, Jonathan Gregory wrote:
>Dear Don
>
>> If I have a temperature, it means coming up with a
>> new standard name for each location (at_sea_level, at_tropopause,
>> at_halocline_top, at_halocline_bottom, etc).  That could quickly
>> get out of hand.  Of course, standard name is optional so you don't
>> have to use it.
>
>It sounds as though it could get out of hand, but in practice it hasn't in CF
>standard names. That's because there are not very many "named" surfaces of
>this kind. Mostly the vertical level is specified with a coordinate variable
>(height, depth, pressure, etc.), and then the standard name does not indicate
>the surface. However
>
>(a) Some surfaces which are defined in some physical way, like the tropopause,
>can't be specified as a vertical coordinate, so they have to be named. Naming
>them as part of the standard name has the advantage that it is impossible to
>omit this information (if you choose to use the standard name). If there was a
>separate string-valued attribute to identify the surface, it might be omitted
>- one more thing which could be defective with the file!
>
>(b) Others could be defined with a vertical coordinate, but it's not the most
>helpful thing to do, I'd say. Sea level, for example, could be called depth=0
>or height=0. It's not so convenient for software to have to be aware of various
>different equivalent definitions. I think that when we say "sea level" we
>really have a particular surface in mind, and it's not natural to invent a
>numerical coordinate to identify; it's more natural to name it.
>
>Best wishes
>
>Jonathan
>_______________________________________________
>cf-pointobsconvention mailing list
>cf-pointobsconvention at unidata.ucar.edu
>For list information or to unsubscribe,  visit: http://www.unidata.ucar.edu/mailing_lists/


-- 
----------
John Graybeal   <mailto:graybeal at mbari.org>  -- 831-775-1956
Monterey Bay Aquarium Research Institute
Marine Metadata Initiative: http://marinemetadata.org   ||  
Shore Side Data System: http://www.mbari.org/ssds