Maybe a simpler approach would be to just adopt "platform_altitude" as an alias for "surface_altitude" and suggest deprecating the use of "surface_altitude"?
On Thu, Sep 18, 2014 at 11:15 AM, John Graybeal <[email protected]> wrote: > Interesting that there is so little discussion of this language in the mail > list, only in John Caron's 2011.09.16 mail on standard names for stations > (which refers to words already in draft 1.6, I think) -- which came at the > tail end of a long thread on platform names/IDs. > > From those words, I infer that the original drafter thought surface_altitude > was just as good for describing platform location, as it was for describing > observation location. I suspect the assumption was that any corresponding > observations were at the same location as the platform. > > Since this is not always true, I'm with you that there should be a term > platform altitude, and it should be the one used in this sentence. > > I hereby propose the standard name platform_surface_altitude (m), "Standard > names for platform describe the motion and orientation of the vehicle from > which observations are made e.g. aeroplane, ship or satellite. > The surface called "surface" means the lower boundary of the atmosphere. > Altitude is the (geometric) height above the horizontal reference surface." > > Note I've changed the standard wording of the _altitude definition, which > generally says ".. above the geoid, which is the reference geopotential > surface. The geoid is similar to mean sea level." This seems clearly in > conflict with the definition of surface_altitude and this new term, and I > think it should be changed in surface_altitude's definition too. > > I suppose if people agree with you and me, we need to do a Trac ticket for > the corresponding change to the standard. > > John > > > > On Sep 18, 2014, at 06:40, Signell, Richard <[email protected]> wrote: > >> In the CF-1.6 and CF-1.7 draft doc, in section H.2, we have: >> >> "It is recommended that there should be station variables with >> standard_name attributes " platform_name ", " surface_altitude " and “ >> platform_id ” when applicable." >> >> Why is this "surface_altitude" instead of "platform_altitude"? >> >> In the ocean, we have lots of upward-looking Acoustic Doppler Current >> Profilers (ADCP), where the instrument with transducer and other >> sensors is located some distance below the ocean surface. While >> velocity and other properties are measured in vertical bins above the >> instrument (timeSeriesProfile), other properties like pressure and >> temperature are measured at the instrument. >> >> Since the instrument is not at the surface, it seems misleading to use >> the standard_name "surface_altitude" instead of "platform_altitude", >> particularly when we already have "platform_name" and "platform_id". >> >> In this example CF_1.6 ADCP dataset: >> >> http://geoport.whoi.edu/thredds/dodsC/usgs/data2/rsignell/data/adcp/7201adc-a_cf16.nc.html >> >> the variable "platform_altitude" has a value of -10.4522 m: >> http://geoport.whoi.edu/thredds/dodsC/usgs/data2/rsignell/data/adcp/7201adc-a_cf16.nc.ascii?platform_altitude >> >> but we are forced to use a standard_name of "surface_altitude". >> >> Why not "platform_altitude"? >> >> Thanks, >> Rich >> >> -- >> Dr. Richard P. Signell (508) 457-2229 >> USGS, 384 Woods Hole Rd. >> Woods Hole, MA 02543-1598 >> _______________________________________________ >> CF-metadata mailing list >> [email protected] >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > -- Dr. Richard P. Signell (508) 457-2229 USGS, 384 Woods Hole Rd. Woods Hole, MA 02543-1598 _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
