Re: [CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
Jonathan, This all makes sense to me. If you would be willing to propose the ticket, I would definitely support it. -Rich On Fri, Sep 19, 2014 at 9:37 AM, Jonathan Gregory wrote: > Dear John and Rich > > I think platform_altitude would be fine as a standard name. Altitude means > above the geoid. CF does not define a default geoid. At present it is not > possible to specify what geoid is being used (if you wish to be precise) > but > we have discussed this a few times before. I append some stuff which I > wrote > in an email to Rich and others in May. To implement this would require a > trac > ticket, proposing to define a geoid_name attribute in Appendix F for the > grid_mapping variable. I will propose the ticket if you'd support it. > > Best wishes > > Jonathan > > * Vertical coordinate variables generally have CF standard_name attributes > (standard_names are recommended, though not mandatory). The standard_name > defines the vertical coordinate relative to a geophysically described > surface > e.g. geoid, ellipsoid, mean sea level, surface (= bottom of atmosphere). > Hence > it would be redundant to identify the vertical datum in a geophysical way > in > any other part of CF metadata. I mean, for instance, CF does *not* have > vertical coordinate variables of "height" generically. The "height" is > always > defined as being wrt a geophysical surface. (The standard_name of height > means specifically height above the surface i.e. land or sea surface.) > > * Some of these special surfaces, especially ellipsoid and geoid, need more > precise definitions for some purposes. The existing CF grid_mapping > mechanism > can define the ellipsoid in terms which translate obviously to WKT terms > (see > ticket 80 http://kitt.llnl.gov/trac/ticket/80. (This ticket is agreed but > not > yet implemented in the CF standard document.) It would be easy, and I think > logical, to add an attribute of geoid_name to identify the geoid. > > > - Forwarded message from John Caron - > > > Date: Thu, 18 Sep 2014 14:01:15 -0600 > > From: John Caron > > To: "Signell, Richard" > > CC: CF Metadata List , John Graybeal > > > > Subject: Re: [CF-metadata] Why "surface_altitude" instead of > > "platform_altitude"? > > > > As I recall, the original proposal was for station_altitude. We decided > to > > change "station" to "platform". At the same time it was thought that the > > existing standard name of "surface altitude" would be synonymous. I at > > least was thinking of ground stations. So I think we make a mistake there > > and "platform_altitude" would be the right correction. > > > > An altitude of course needs a datum, and I think we have not been clear > > enough on that. I think we should review our use or non-use of vertical > > datum. A quick look seems to imply that "WGS 84" is assumed (?) > > > > On Thu, Sep 18, 2014 at 1:42 PM, Signell, Richard > wrote: > > > > > John, > > > So then the surface needs to be defined relative to some known datum, > no? > > > > > > Maybe we need platform_altitude_above_datum and a specification of > > > the vertical datum (EPSG:5701 (MSL), EPSG:5703 (NAVD88), etc) > > > > > > On Thu, Sep 18, 2014 at 1:47 PM, John Graybeal > > > wrote: > > > > I assume surface_altitude is an important variable for providing the > > > vertical location of measurements relative to a surface (as opposed to > > > relative to a geoid -- notwithstanding the definition issue). > > > > > > > > John > > > > > > > > On Sep 18, 2014, at 08:30, Signell, Richard > wrote: > > > > > > > >> 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 > > > >> 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
Re: [CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
Dear John and Rich I think platform_altitude would be fine as a standard name. Altitude means above the geoid. CF does not define a default geoid. At present it is not possible to specify what geoid is being used (if you wish to be precise) but we have discussed this a few times before. I append some stuff which I wrote in an email to Rich and others in May. To implement this would require a trac ticket, proposing to define a geoid_name attribute in Appendix F for the grid_mapping variable. I will propose the ticket if you'd support it. Best wishes Jonathan * Vertical coordinate variables generally have CF standard_name attributes (standard_names are recommended, though not mandatory). The standard_name defines the vertical coordinate relative to a geophysically described surface e.g. geoid, ellipsoid, mean sea level, surface (= bottom of atmosphere). Hence it would be redundant to identify the vertical datum in a geophysical way in any other part of CF metadata. I mean, for instance, CF does *not* have vertical coordinate variables of "height" generically. The "height" is always defined as being wrt a geophysical surface. (The standard_name of height means specifically height above the surface i.e. land or sea surface.) * Some of these special surfaces, especially ellipsoid and geoid, need more precise definitions for some purposes. The existing CF grid_mapping mechanism can define the ellipsoid in terms which translate obviously to WKT terms (see ticket 80 http://kitt.llnl.gov/trac/ticket/80. (This ticket is agreed but not yet implemented in the CF standard document.) It would be easy, and I think logical, to add an attribute of geoid_name to identify the geoid. - Forwarded message from John Caron - > Date: Thu, 18 Sep 2014 14:01:15 -0600 > From: John Caron > To: "Signell, Richard" > CC: CF Metadata List , John Graybeal > > Subject: Re: [CF-metadata] Why "surface_altitude" instead of > "platform_altitude"? > > As I recall, the original proposal was for station_altitude. We decided to > change "station" to "platform". At the same time it was thought that the > existing standard name of "surface altitude" would be synonymous. I at > least was thinking of ground stations. So I think we make a mistake there > and "platform_altitude" would be the right correction. > > An altitude of course needs a datum, and I think we have not been clear > enough on that. I think we should review our use or non-use of vertical > datum. A quick look seems to imply that "WGS 84" is assumed (?) > > On Thu, Sep 18, 2014 at 1:42 PM, Signell, Richard wrote: > > > John, > > So then the surface needs to be defined relative to some known datum, no? > > > > Maybe we need platform_altitude_above_datum and a specification of > > the vertical datum (EPSG:5701 (MSL), EPSG:5703 (NAVD88), etc) > > > > On Thu, Sep 18, 2014 at 1:47 PM, John Graybeal > > wrote: > > > I assume surface_altitude is an important variable for providing the > > vertical location of measurements relative to a surface (as opposed to > > relative to a geoid -- notwithstanding the definition issue). > > > > > > John > > > > > > On Sep 18, 2014, at 08:30, Signell, Richard wrote: > > > > > >> 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 > > >> 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 mad
Re: [CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
As I recall, the original proposal was for station_altitude. We decided to change "station" to "platform". At the same time it was thought that the existing standard name of "surface altitude" would be synonymous. I at least was thinking of ground stations. So I think we make a mistake there and "platform_altitude" would be the right correction. An altitude of course needs a datum, and I think we have not been clear enough on that. I think we should review our use or non-use of vertical datum. A quick look seems to imply that "WGS 84" is assumed (?) On Thu, Sep 18, 2014 at 1:42 PM, Signell, Richard wrote: > John, > So then the surface needs to be defined relative to some known datum, no? > > Maybe we need platform_altitude_above_datum and a specification of > the vertical datum (EPSG:5701 (MSL), EPSG:5703 (NAVD88), etc) > > On Thu, Sep 18, 2014 at 1:47 PM, John Graybeal > wrote: > > I assume surface_altitude is an important variable for providing the > vertical location of measurements relative to a surface (as opposed to > relative to a geoid -- notwithstanding the definition issue). > > > > John > > > > On Sep 18, 2014, at 08:30, Signell, Richard wrote: > > > >> 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 > >> 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 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 > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > >>> > >
Re: [CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
John, So then the surface needs to be defined relative to some known datum, no? Maybe we need platform_altitude_above_datum and a specification of the vertical datum (EPSG:5701 (MSL), EPSG:5703 (NAVD88), etc) On Thu, Sep 18, 2014 at 1:47 PM, John Graybeal wrote: > I assume surface_altitude is an important variable for providing the vertical > location of measurements relative to a surface (as opposed to relative to a > geoid -- notwithstanding the definition issue). > > John > > On Sep 18, 2014, at 08:30, Signell, Richard wrote: > >> 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 >> 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 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 CF-metadata@cgd.ucar.edu 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 > -- Dr. Richard P. Signell (508) 457-2229 USGS, 384 Woods Hole Rd. Woods Hole, MA 02543-1598 ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
I assume surface_altitude is an important variable for providing the vertical location of measurements relative to a surface (as opposed to relative to a geoid -- notwithstanding the definition issue). John On Sep 18, 2014, at 08:30, Signell, Richard wrote: > 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 > 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 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 >>> CF-metadata@cgd.ucar.edu >>> 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 CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
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 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 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 >> CF-metadata@cgd.ucar.edu >> 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 CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
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 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 > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
[CF-metadata] Why "surface_altitude" instead of "platform_altitude"?
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 CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
