Yeah, Xerox didn't think much of it either, but check your dictionaries. Please note I never meant to suggest having just one label, two are clearly needed. I was merely trying to find the optimal end point.
A note to consider: In cases where a definition has become hopeless muddled by practice or overtaken by better practices (see for example sea_surface_temperature), the consensus approach has been to define more clear terms, and ask new users to use one of the more precise/disambiguated terms whenever possible, thus marginalizing the original confusing term. The absence of an existing standard_name to describe what is acknowledged as a large body of existing data makes me believe that possibility is worth evaluating. I promise that's the last I'll say about that. John P.S. Except this refinement to your comments: We change definitions all the time in CF, so the bar for that is clearly not high. But when we invert the meaning, it is of course a little more indelicate. :-> On Jan 10, 2013, at 23:51, Lowry, Roy K. wrote: > Hi John, > > I agree with Philip. Not only does changing existing definitions go against > all my gut instincts, there's another problem with just having a single sea > pressure label. > > Although the practice to correct to zero at sea level is almost universal > when pressure is used as the z co-ordinate, in situations where pressure is > measured as a geophysical phenomenon (e.g. sea level time series measured by > a seabed-mounted pressure sensor) working practices are more variable. Some > subtract actual atmospheric pressure measurements, some subtract a nominal > value and others do nothing. This digs a hole that I think is a little too > deep for semantics to come to the rescue. > > Cheers, Roy. > > From: Cameron-smith, Philip [cameronsmi...@llnl.gov] > Sent: 11 January 2013 01:30 > To: John Graybeal > Cc: Lowry, Roy K.; cf-metadata@cgd.ucar.edu; sdn2-net...@seadatanet.org > Subject: RE: [CF-metadata] sea_water_pressure > > Hi John, > > I have seen similar situations in atmospheric chemistry. I participated in > an intercomparison in which we submitted exactly what the std_name required, > only to find out that every other group had submitted what they assumed it > meant, which was several orders of magnitude different. > > I think the bar for retroactively changing a definition should be very high > (without commenting on the merits of your case). One thing we can do to > help, without causing any problems, is to add to existing descriptions a list > of related std_names so that a user will get a 'heads up' to look at other > std_names. I know this is only a partial solution, but better than nothing. > > Best wishes, > > Philip > > ----------------------------------------------------------------------- > Dr Philip Cameron-Smith, p...@llnl.gov, Lawrence Livermore National Lab. > ----------------------------------------------------------------------- > > > From: John Graybeal [mailto:jgrayb...@ucsd.edu] > Sent: Thursday, January 10, 2013 3:48 PM > To: Cameron-smith, Philip > Cc: Lowry, Roy K.; cf-metadata@cgd.ucar.edu; sdn2-net...@seadatanet.org > Subject: Re: [CF-metadata] sea_water_pressure > > It looks sensible to me, too, but I have to ask a stupid question. Of all the > data with "sea_water_pressure" CF standard names in the world, how many are > actually presenting what CF defines that to be? (If the answer is "very > few", maybe the answer is that the definition is just mis-stated for what the > community expected, and we need a new term to go with the existing > definition.) > > (Yes, this is a perspective that only an ontologist could offer without > embarrassment.) > > John > > > > > On Jan 10, 2013, at 15:16, Cameron-smith, Philip wrote: > > > Hi Roy, > > This looks sensible to me. > > Philip > > ----------------------------------------------------------------------- > Dr Philip Cameron-Smith, p...@llnl.gov, Lawrence Livermore National Lab. > ----------------------------------------------------------------------- > > > From: CF-metadata [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of > Lowry, Roy K. > Sent: Thursday, January 10, 2013 1:01 AM > To: cf-metadata@cgd.ucar.edu > Cc: sdn2-net...@seadatanet.org > Subject: [CF-metadata] sea_water_pressure > > Dear All, > > It has been pointed out to me that the SeaDataNet NetCDF specification uses > 'sea_water_pressure' as the Standard Name in cases where pressure is used as > the z co-ordinate in observational data such as CTD profiles. The definition > for this Standard Name is: > > the pressure that exists in the medium of sea water. It includes the > pressure due to overlying sea water, sea ice, air and any other medium that > may be present. > > Consequently the expected pressure z co-ordinate labelled > 'sea_water_pressure' would be approximately 10 decibars at the sea surface. > However, it is almost universal practice to either calibrate or correct the > pressure z co-ordinate so that it reads zero at the sea surface. > Consequently, I think we need a new Standard Name: > > sea_water_pressure_due_to_sea_water defined as > > the pressure that exists in the medium of sea water due to overlying sea > water. Excludes the pressure due to sea ice, air and any other medium that > may be present. > > Apologies to anybody else who like me had used 'sea_water_pressure' for their > Z co-ordinate without looking at the definition. > > Cheers, Roy. > > Please note that I now work part-time from Tuesday to Thursday. E-mail > response on other days is possible but not guaranteed! > > > > ________________________________ > This message (and any attachments) is for the recipient only. NERC is subject > to the Freedom of Information Act 2000 and the contents of this email and any > reply you make may be disclosed by NERC unless it is exempt from release > under the Act. Any material supplied to NERC may be stored in an electronic > records management system. > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > ---------------- > John Graybeal <mailto:jgrayb...@ucsd.edu> phone: 858-534-2162 > Product Manager > Ocean Observatories Initiative Cyberinfrastructure Project: > http://ci.oceanobservatories.org > Marine Metadata Interoperability Project: http://marinemetadata.org > > > > > > > > > This message (and any attachments) is for the recipient only. NERC is subject > to the Freedom of Information Act 2000 and the contents of this email and any > reply you make may be disclosed by NERC unless it is exempt from release > under the Act. Any material supplied to NERC may be stored in an electronic > records management system. ---------------- John Graybeal <mailto:jgrayb...@ucsd.edu> phone: 858-534-2162 Product Manager Ocean Observatories Initiative Cyberinfrastructure Project: http://ci.oceanobservatories.org Marine Metadata Interoperability Project: http://marinemetadata.org
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