Re: [CF-metadata] seeking CF name for total water column height
Dear Jeff, Thank you for your standard name proposal for water column height and thanks to all who have contributed comments to this discussion. The consensus view seems to be that sea_floor_depth_below_sea_surface is an acceptable name for this quantity and that it is consistent with the existing standard name sea_floor_depth_below_sea_level. The canonical units will be metres (m). Roy has suggested the following definition: 'The vertical distance between the sea surface and the seabed as measured at a given point in space including the variance caused by tides and possibly waves.' If no further comments on this name or its definition are received over the next seven days then they will be accepted in their present form for inclusion in the standard name table. You have also suggested two further standard names: water_level_with|above_reference_datum water_level_without_reference_datum For the latter name, Roy has suggested the term 'tide gauge zero' to express the lack of reference datum. Am I correct in thinking that all these quantities are referring to measurements in the open sea or coastal areas? If so, I think we should refer to sea_surface_height rather than water_level for consistency with other names. So we could have: sea_surface_height_above_reference_datum sea_surface_height_above_tide_gauge_zero. I am wondering how many different reference datums there are likely to be? You mentioned low water and highest astronomical tide but are there likely to be dozens of these quantities? If there are only a few we could consider introducing separate standard names for them as we have done with quantities such as sea_surface_height_above_reference_ellipsoid and sea_surface_height_above_geoid for example. If there are a large number of possible datums then it wouldn't be practical to introduce standard names for them all and we would need another way to record which datum is being used. Regarding the definitions, do both quantities average out the effects of waves? Nan has raised the question of how to distinguish between the same geophysical quantity measured with different sensors/sensor configurations or post-processed differently. This question has arisen in a number of contexts recently. For example, as well as sea water pressure and depth measurements, we discussed some CMIP5 proposals in which climate models were simulating cloud amounts as retrieved from two different satellite instruments. In the case of CMIP5 I believe the issue was resolved by using the same standard name for both quantities and placing them in differently named files, but a simple way of distinguishing between instruments/instrument types/retrieval algorithms in metadata would be to use the 'source' attribute which can be either global or attached to a single variable (this is already part of the CF conventions, section 2.6.2). Best wishes, Alison -- Alison Pamment Tel: +44 1235 778065 NCAS/British Atmospheric Data CentreFax: +44 1235 446314 Rutherford Appleton Laboratory Email: alison.pamm...@stfc.ac.uk Chilton, Didcot, OX11 0QX, U.K. -- Scanned by iCritical. ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] seeking CF name for total water column height
Hi Alison, *About the 'water level' vs 'sea surface height' In the case of Jeff needs would only concern ocean data, would you mind if I ask CF to introduce both? I was about to ask CF for such quantities on rivers and lakes.. *About reference datum, my opinion is that considering CF standard name is supposed to uniquely identify one geophysical field, we should ask: are there as many standard names as there are datums? Is the sea surface height above French Naval Chart Datum geophysically different from the sea surface height above French Naval Chart Datum for Lebanon? If the answer is yes, I guess introducing a new datum attribute in CF would be relevant. By the way if we consider the sea surface height above geoid, geoid is not exactly a datum, or became indirectly a datum: the whole quantity refers first to the geophysical information retrieved, which is the absolute ocean topography, and which is not obtained by measuring some heights and subtracting geoid heights from. It is really full of meaning in terms of ocean dynamics - and less on the way it was really measured.. *I confirm that what you explained about distinction between the same geophysical field obtained by different sensors was also applied by OSTST/Jason community. In the NetCDF product you can have 2 variables with the same standard name, but one is obtained via the onboard instrument, and the second via ECMWF forecasts. It is another illustration. Cheers, Olivier. -Message d'origine- De : cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] De la part de alison.pamm...@stfc.ac.uk Envoyé : vendredi 12 février 2010 12:15 À : cf-metadata@cgd.ucar.edu Objet : Re: [CF-metadata] seeking CF name for total water column height Dear Jeff, Thank you for your standard name proposal for water column height and thanks to all who have contributed comments to this discussion. The consensus view seems to be that sea_floor_depth_below_sea_surface is an acceptable name for this quantity and that it is consistent with the existing standard name sea_floor_depth_below_sea_level. The canonical units will be metres (m). Roy has suggested the following definition: 'The vertical distance between the sea surface and the seabed as measured at a given point in space including the variance caused by tides and possibly waves.' If no further comments on this name or its definition are received over the next seven days then they will be accepted in their present form for inclusion in the standard name table. You have also suggested two further standard names: water_level_with|above_reference_datum water_level_without_reference_datum For the latter name, Roy has suggested the term 'tide gauge zero' to express the lack of reference datum. Am I correct in thinking that all these quantities are referring to measurements in the open sea or coastal areas? If so, I think we should refer to sea_surface_height rather than water_level for consistency with other names. So we could have: sea_surface_height_above_reference_datum sea_surface_height_above_tide_gauge_zero. I am wondering how many different reference datums there are likely to be? You mentioned low water and highest astronomical tide but are there likely to be dozens of these quantities? If there are only a few we could consider introducing separate standard names for them as we have done with quantities such as sea_surface_height_above_reference_ellipsoid and sea_surface_height_above_geoid for example. If there are a large number of possible datums then it wouldn't be practical to introduce standard names for them all and we would need another way to record which datum is being used. Regarding the definitions, do both quantities average out the effects of waves? Nan has raised the question of how to distinguish between the same geophysical quantity measured with different sensors/sensor configurations or post-processed differently. This question has arisen in a number of contexts recently. For example, as well as sea water pressure and depth measurements, we discussed some CMIP5 proposals in which climate models were simulating cloud amounts as retrieved from two different satellite instruments. In the case of CMIP5 I believe the issue was resolved by using the same standard name for both quantities and placing them in differently named files, but a simple way of distinguishing between instruments/instrument types/retrieval algorithms in metadata would be to use the 'source' attribute which can be either global or attached to a single variable (this is already part of the CF conventions, section 2.6.2). Best wishes, Alison -- Alison Pamment Tel: +44 1235 778065 NCAS/British Atmospheric Data CentreFax: +44 1235 446314 Rutherford Appleton Laboratory Email: alison.pamm...@stfc.ac.uk Chilton, Didcot
Re: [CF-metadata] seeking CF name for total water column height
Hi Roy - I was arguing at the start of this thread ... This first came up in August, 2008: Subject: Same parameter, different meaning (pressure) Can (or should) the CF standard differentiate between these two very different measurements of sea water pressure: The consensus then was that we should use a single name and infer the meaning of the data from metadata about how the sensor was mounted. ... that an instantaneous single-beam echosounder measurement is the so close to being the same thing as a BPR measurement in tidal mode with waves filtered out (ever looked at echosounder data from an anchored ship?) that they should be called the same thing on the basis that the Standard Name represents the phenomenon and should not describe how it was measured. Exactly; they're comparable when the BPR is processed in a specific way - and not comparable otherwise. So, does data from the different modes of a pressure recorder (or data that's been post-processed as you describe) constitute different physical phenomena, worthy of different standard names, or not? It looks like we're sticking with the original decision, and using a single name, but users will need to come to some agreement on how to document the sensor mounting and/or post-processing, to provide enough information to understand the meaning of the data. Cheers - Nan From: Nan Galbraith [ngalbra...@whoi.edu] Sent: 04 February 2010 17:29 Subject: Re: [CF-metadata] seeking CF name for total water column height Sea_floor_depth_below_sea_surface seems very appropriate when the water depth is measured from the surface. Some communities need to distinguish this measurement from one made from the sea floor. Shipboard water depth measurements in the open ocean generally ignore tides and other variations in sea surface height, while bottom pressure recorders or other instruments used in transport studies are monitoring these differences. The oceansites project is looking for a way to identify this distinction - maybe having 2 water depth terms in CF will be the solution, although it may not be clear enough (especially since most people seem to think these terms are synonyms). If this has been mentioned, please excuse; I've been on a ship with terrible network throughput, and I'm slowly trying to catch up with email discussions. Cheers - Nan -- *** * Nan Galbraith(508) 289-2444 * * Upper Ocean Processes GroupMail Stop 29 * * Woods Hole Oceanographic Institution* * Woods Hole, MA 02543* *** ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] seeking CF name for total water column height
Hello Nan, I was arguing at the start of this thread that an instantaneous single-beam echosounder measurement is the so close to being the same thing as a BPR measurement in tidal mode with waves filtered out (ever looked at echosounder data from an anchored ship?) that they should be called the same thing on the basis that the Standard Name represents the phenomenon and should not describe how it was measured. Cheers, Roy. From: cf-metadata-boun...@cgd.ucar.edu [cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Nan Galbraith [ngalbra...@whoi.edu] Sent: 04 February 2010 17:29 To: Jonathan Gregory Cc: cf-metadata@cgd.ucar.edu; Mike Garcia Subject: Re: [CF-metadata] seeking CF name for total water column height Sea_floor_depth_below_sea_surface seems very appropriate when the water depth is measured from the surface. Some communities need to distinguish this measurement from one made from the sea floor. Shipboard water depth measurements in the open ocean generally ignore tides and other variations in sea surface height, while bottom pressure recorders or other instruments used in transport studies are monitoring these differences. The oceansites project is looking for a way to identify this distinction - maybe having 2 water depth terms in CF will be the solution, although it may not be clear enough (especially since most people seem to think these terms are synonyms). If this has been mentioned, please excuse; I've been on a ship with terrible network throughput, and I'm slowly trying to catch up with email discussions. Cheers - Nan I agree, it is arbitrary whether it is called sea_floor_depth_below_sea_surface or sea_surface_height_above_sea_floor and I agree with Roy that consistency with existing names would suggest the former. It's interesting that this kind of ambiguity hasn't arisen before. What you want to name is the distance between two named surfaces. In other names, we call the vertical distance between two surfaces a thickness e.g. ocean_mixed_layer_thickness. That doesn't have an associated direction (upward or downward) and so avoids this problem. By that analogy the quantity you want to name might be called thickness_of_ocean but I suspect most people would find that less obvious. What we are aiming at principally is clarity. The procedure for adding names is that Alison Pamment, the manager of standard names, will consider them and add them. She is dealing with CMIP5 names at present, I believe, so it might be a while before she gets to this. If no-one else objects soon or makes an alternative proposal, I'd suggest you use this name on the assumption that it will be added to the stdname table in due course. Best wishes Jonathan -- *** * Nan Galbraith(508) 289-2444 * * Upper Ocean Processes GroupMail Stop 29 * * Woods Hole Oceanographic Institution* * Woods Hole, MA 02543* *** ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- 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
Re: [CF-metadata] seeking CF name for total water column height
Sea_floor_depth_below_sea_surface seems very appropriate when the water depth is measured from the surface. Some communities need to distinguish this measurement from one made from the sea floor. Shipboard water depth measurements in the open ocean generally ignore tides and other variations in sea surface height, while bottom pressure recorders or other instruments used in transport studies are monitoring these differences. The oceansites project is looking for a way to identify this distinction - maybe having 2 water depth terms in CF will be the solution, although it may not be clear enough (especially since most people seem to think these terms are synonyms). If this has been mentioned, please excuse; I've been on a ship with terrible network throughput, and I'm slowly trying to catch up with email discussions. Cheers - Nan I agree, it is arbitrary whether it is called sea_floor_depth_below_sea_surface or sea_surface_height_above_sea_floor and I agree with Roy that consistency with existing names would suggest the former. It's interesting that this kind of ambiguity hasn't arisen before. What you want to name is the distance between two named surfaces. In other names, we call the vertical distance between two surfaces a thickness e.g. ocean_mixed_layer_thickness. That doesn't have an associated direction (upward or downward) and so avoids this problem. By that analogy the quantity you want to name might be called thickness_of_ocean but I suspect most people would find that less obvious. What we are aiming at principally is clarity. The procedure for adding names is that Alison Pamment, the manager of standard names, will consider them and add them. She is dealing with CMIP5 names at present, I believe, so it might be a while before she gets to this. If no-one else objects soon or makes an alternative proposal, I'd suggest you use this name on the assumption that it will be added to the stdname table in due course. Best wishes Jonathan -- *** * Nan Galbraith(508) 289-2444 * * Upper Ocean Processes GroupMail Stop 29 * * Woods Hole Oceanographic Institution* * Woods Hole, MA 02543* *** ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
[CF-metadata] seeking CF name for total water column height
Dear Jeff and Roy I agree, it is arbitrary whether it is called sea_floor_depth_below_sea_surface or sea_surface_height_above_sea_floor and I agree with Roy that consistency with existing names would suggest the former. It's interesting that this kind of ambiguity hasn't arisen before. What you want to name is the distance between two named surfaces. In other names, we call the vertical distance between two surfaces a thickness e.g. ocean_mixed_layer_thickness. That doesn't have an associated direction (upward or downward) and so avoids this problem. By that analogy the quantity you want to name might be called thickness_of_ocean but I suspect most people would find that less obvious. What we are aiming at principally is clarity. The procedure for adding names is that Alison Pamment, the manager of standard names, will consider them and add them. She is dealing with CMIP5 names at present, I believe, so it might be a while before she gets to this. If no-one else objects soon or makes an alternative proposal, I'd suggest you use this name on the assumption that it will be added to the stdname table in due course. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] seeking CF name for total water column height
Perhaps the infamous aliases would be an appropriate technique? I seem to recall that aliases are considered OK in some cases in CF, or am I remembering that incorrectly? I like the idea of 'distance_between_sea_floor_and_sea_surface' myself, rather than 'thickness_of_ocean' (though the latter is elegant too!). But in any case, it would be delightful if the two (three?) alternatives were also present, for searchers. John On Feb 2, 2010, at 10:22, Jonathan Gregory wrote: Dear Jeff and Roy I agree, it is arbitrary whether it is called sea_floor_depth_below_sea_surface or sea_surface_height_above_sea_floor and I agree with Roy that consistency with existing names would suggest the former. It's interesting that this kind of ambiguity hasn't arisen before. What you want to name is the distance between two named surfaces. In other names, we call the vertical distance between two surfaces a thickness e.g. ocean_mixed_layer_thickness. That doesn't have an associated direction (upward or downward) and so avoids this problem. By that analogy the quantity you want to name might be called thickness_of_ocean but I suspect most people would find that less obvious. What we are aiming at principally is clarity. The procedure for adding names is that Alison Pamment, the manager of standard names, will consider them and add them. She is dealing with CMIP5 names at present, I believe, so it might be a while before she gets to this. If no-one else objects soon or makes an alternative proposal, I'd suggest you use this name on the assumption that it will be added to the stdname table in due course. Best wishes Jonathan ___ 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
Re: [CF-metadata] seeking CF name for total water column height
Dear John Yes, good suggestion, we could adopt a new pattern vertical_distance_between_X and_Y for cases where thickness sounds peculiar. Aliases are really intended for cases where we make mistakes or change our minds, rather than to provide synonyms deliberately. We've preferred to force ourselves to agree where possible on a minimal vocabulary. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] seeking CF name for total water column height
Dear Jonathan, The alias structure has developed into a deprecation mechanism and some of the more recent corrections have changed the meanings of the terms, so that the term and its alias are no longer synonyms. Using the alias mechanism to establish synonyms between undeprecated terms invites confusion - it's like building RDF triples with no predicate. Should the decision be taken to develop the Standard Names into a semantic network (which has been advocated at GO-ESSP meetings) then a more robust mechanism for specifying the relationship between terms is needed. I can support this, but the infrastructure on the CF site would need a minor upgrade. Cheers, Roy. From: cf-metadata-boun...@cgd.ucar.edu [cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Jonathan Gregory [j.m.greg...@reading.ac.uk] Sent: 02 February 2010 18:43 To: John Graybeal Cc: CF Metadata List Subject: Re: [CF-metadata] seeking CF name for total water column height Dear John Yes, good suggestion, we could adopt a new pattern vertical_distance_between_X and_Y for cases where thickness sounds peculiar. Aliases are really intended for cases where we make mistakes or change our minds, rather than to provide synonyms deliberately. We've preferred to force ourselves to agree where possible on a minimal vocabulary. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- 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
Re: [CF-metadata] seeking CF name for total water column height
In general, when CF has a measured observable, the name makes no statement about whether the variable has been measured instantaneously, or for 1 hour, or for one month. It's time-neutral. ... because you can use other cf attributes to say things about time averaging ( intensivity/extensivity etc) implicit in the measurement/simulation ... Bryan -- Bryan Lawrence Director of Environmental Archival and Associated Research (NCAS/British Atmospheric Data Centre and NCEO/NERC NEODC) STFC, Rutherford Appleton Laboratory Phone +44 1235 445012; Fax ... 5848; Web: home.badc.rl.ac.uk/lawrence ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] seeking CF name for total water column height
Hi Jeff, My motives for 'looking down' rather than 'looking up' were that we already had a 'sea_floor_depth_below_mean_sea_level' and established practice with CF name development has been to be as consistent as possible with name structure. Jonathan Gregory has led this development in the past - let's see what his take is on the best name syntax. The issue of encoding sea level measurements relative to reference datums other than MSL has been discussed on the list at length previously and I don't recall our ever reaching a satisfactory resolution. It might be worth your having a trawl around the archives or waiting for somebody with a better memory than me to summarise where the discussion had reached. Incidentally, I have seen the 'datum' for streams without a datum described as 'tide gauge zero', which often has a physical manifestation such as a metal peg driven into a wall. Cheers, Roy. -Original Message- From: Jeff deLaBeaujardiere [mailto:jeff.delabeaujardi...@noaa.gov] Sent: 28 January 2010 14:06 To: Lowry, Roy K Cc: John Graybeal; cf-metadata@cgd.ucar.edu; Mike Garcia Subject: Re: [CF-metadata] seeking CF name for total water column height I should mention that there are other types of water level measurements for which we will want names. These are instruments such as tide gauges that measure water relative to a reference datum (such as mean lower low water, or highest astronomical tide), or stream gauges that measure relative to the station itself but not a formal datum. I spoke about this yesterday afternoon with some water-level experts at NOAA CO-OPS, and we felt that three new CF names like the following might suffice: sea_floor_depth_below_sea_surface[*] water_level_with_reference datum (or above instead of with) water_level_without_reference datum [*] Looking at this one again, I wonder whether sea_surface_height_above_sea_floor would be more appropriate. NDBC had suggested total_water_column_height. -Jeff DLB Lowry, Roy K wrote: Hi John, Ah, I thought you were objecting to having different names for different averaging intervals. Let's see if I can improve the definition. There are three varieties of water depth (sea_floor_depth_below_sea_surface) that I've encountered. 1 Instantaneous measurements collected at high frequency over a short time interval designed to quantify waves. These are normally reduced to a raft of wave statistics by processing on board the instrument and I've certainly never seen them as a stream and so didn't see any point in setting up a separate standard name. 2 Measurements averaged over a sampling interval (an hour or shorter) to filter out variance caused by normal waves but not tide (or unusually long period waves). This is Jeff's stream, and also pretty much what is measured by an echosounder mounted on all but the smallest ship. 3 Long-term averages or nominal calculations by models that filter out (or ignore in the case of models) the variances caused by waves and tide - which are covered by the existing Standard Name 'sea_floor_depth_below_mean_sea_level'. How about 'The vertical distance between the sea surface and the seabed as measured at a given point in space including the variance caused by tides and possibly waves'? Or can you do better? Cheers, Roy. -Original Message- From: John Graybeal [mailto:jbgrayb...@mindspring.com] Sent: 27 January 2010 23:01 To: Lowry, Roy K Cc: cf-metadata@cgd.ucar.edu; Mike Garcia Subject: Re: [CF-metadata] seeking CF name for total water column height I have no concern about whether this stream needs labeling. My concern is whether you are defining something in the definition which is in no way described by the label, and which will prevent that label being used for other variables in other streams. Put another way, what should the models that calculate the nominal sea_floor_depth_below_sea_surface -- or an averaged value longer than 1 hour -- call their values? John On Jan 27, 2010, at 12:54, Lowry, Roy K wrote: Hi John, Simple pragmatism. It's what a BPR data stream tends to contain and so it needs labelling. Cheers, Roy. From: John Graybeal [jbgrayb...@mindspring.com] Sent: 27 January 2010 16:41 To: Lowry, Roy K Cc: Jeff deLaBeaujardiere; cf-metadata@cgd.ucar.edu; Mike Garcia Subject: Re: [CF-metadata] seeking CF name for total water column height Any particular reason that you are biased for this name representing only a short-term value? Seems to me there is equally the need for a (measured or modeled) value that would be defined exactly the same way, but without the time qualifiers. In general, when CF has a measured observable, the name makes no statement about whether the variable has been measured instantaneously, or for 1 hour, or for one month. It's time-neutral. This has several advantages. I
Re: [CF-metadata] seeking CF name for total water column height
Hi, I've been involved in the other sea_surface_above definitions, it was at that time from a sea-level-from-space (radar altimetry) only point of view. Anyway, I've the feeling that you are suggesting Roy reminds more something close to bathymetry. Considering that bathymetry and sea level are very close topics, it's just a question of point of view.. Do you think it would be possible to use both 'sea_floor_depth_below_sea_surface' and 'sea_surface_height_above_sea_floor' with some alias? Only a compromise.. Cheers -Message d'origine- De : cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] De la part de Lowry, Roy K Envoyé : jeudi 28 janvier 2010 16:12 À : Jeff deLaBeaujardiere Cc : John Graybeal; cf-metadata@cgd.ucar.edu; Mike Garcia Objet : Re: [CF-metadata] seeking CF name for total water column height Hi Jeff, My motives for 'looking down' rather than 'looking up' were that we already had a 'sea_floor_depth_below_mean_sea_level' and established practice with CF name development has been to be as consistent as possible with name structure. Jonathan Gregory has led this development in the past - let's see what his take is on the best name syntax. The issue of encoding sea level measurements relative to reference datums other than MSL has been discussed on the list at length previously and I don't recall our ever reaching a satisfactory resolution. It might be worth your having a trawl around the archives or waiting for somebody with a better memory than me to summarise where the discussion had reached. Incidentally, I have seen the 'datum' for streams without a datum described as 'tide gauge zero', which often has a physical manifestation such as a metal peg driven into a wall. Cheers, Roy. -Original Message- From: Jeff deLaBeaujardiere [mailto:jeff.delabeaujardi...@noaa.gov] Sent: 28 January 2010 14:06 To: Lowry, Roy K Cc: John Graybeal; cf-metadata@cgd.ucar.edu; Mike Garcia Subject: Re: [CF-metadata] seeking CF name for total water column height I should mention that there are other types of water level measurements for which we will want names. These are instruments such as tide gauges that measure water relative to a reference datum (such as mean lower low water, or highest astronomical tide), or stream gauges that measure relative to the station itself but not a formal datum. I spoke about this yesterday afternoon with some water-level experts at NOAA CO-OPS, and we felt that three new CF names like the following might suffice: sea_floor_depth_below_sea_surface[*] water_level_with_reference datum (or above instead of with) water_level_without_reference datum [*] Looking at this one again, I wonder whether sea_surface_height_above_sea_floor would be more appropriate. NDBC had suggested total_water_column_height. -Jeff DLB Lowry, Roy K wrote: Hi John, Ah, I thought you were objecting to having different names for different averaging intervals. Let's see if I can improve the definition. There are three varieties of water depth (sea_floor_depth_below_sea_surface) that I've encountered. 1 Instantaneous measurements collected at high frequency over a short time interval designed to quantify waves. These are normally reduced to a raft of wave statistics by processing on board the instrument and I've certainly never seen them as a stream and so didn't see any point in setting up a separate standard name. 2 Measurements averaged over a sampling interval (an hour or shorter) to filter out variance caused by normal waves but not tide (or unusually long period waves). This is Jeff's stream, and also pretty much what is measured by an echosounder mounted on all but the smallest ship. 3 Long-term averages or nominal calculations by models that filter out (or ignore in the case of models) the variances caused by waves and tide - which are covered by the existing Standard Name 'sea_floor_depth_below_mean_sea_level'. How about 'The vertical distance between the sea surface and the seabed as measured at a given point in space including the variance caused by tides and possibly waves'? Or can you do better? Cheers, Roy. -Original Message- From: John Graybeal [mailto:jbgrayb...@mindspring.com] Sent: 27 January 2010 23:01 To: Lowry, Roy K Cc: cf-metadata@cgd.ucar.edu; Mike Garcia Subject: Re: [CF-metadata] seeking CF name for total water column height I have no concern about whether this stream needs labeling. My concern is whether you are defining something in the definition which is in no way described by the label, and which will prevent that label being used for other variables in other streams. Put another way, what should the models that calculate the nominal sea_floor_depth_below_sea_surface -- or an averaged value longer than 1 hour -- call their values? John On Jan 27, 2010, at 12:54, Lowry, Roy K wrote: Hi John
Re: [CF-metadata] seeking CF name for total water column height
Dear All, I think a new Standard Name 'sea_floor_depth_below_sea_surface' is what's needed here. My definition for this would be 'The vertical distance between the sea surface and the seabed at a given point in space and at a given instant in time or averaged over a time interval that is significantly less than a tidal cycle (1 hour or less).' This may seem complicated, but is needed to cover BPRs which do some averaging to smooth out waves. My take on 'height_above_sea_floor' would be as the z co-ordinate for something inside a water body. May be worth pointing out to Jeff that there is already 'sea_water_pressure_at_sea_floor' for BPR data that haven't been converted to depth. I've expressed this as a depth rather than as a height to be consistent with 'sea_floor_depth_below_sea_level' and so we don't end up with different terms for the same quantity depending upon whether one is looking upwards or downwards. Cheers, Roy. -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Jeff deLaBeaujardiere Sent: 26 January 2010 22:22 To: cf-metadata@cgd.ucar.edu Cc: Mike Garcia Subject: [CF-metadata] seeking CF name for total water column height Hello- I am a new subscriber. We are hoping to adopt CF names wherever possible in the context of the Integrated Ocean Observing System (IOOS) Sensor Observation Services (SOS). Not all phenomena we measure have immediately apparent CF names, however. We are using this URL as a reference: http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-table/current/cf-standard-name-table.html The first example is total water column height as derived from a bottom pressure recorder associated with a tsunami warning buoy. This is not sea_surface_height_above_reference_ellipsoid or _above_sea_level. It might be height_above_sea_floor but we're not really sure what that refers to (height of what?). Is there a standard name present or planned that is equivalent to total_water_column_height? Thanks for any information, Jeff DLB -- Jeff de La Beaujardière, 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.delabeaujardi...@noaa.gov ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- 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
Re: [CF-metadata] seeking CF name for total water column height
Hello Roy, Hello Jeff, Just to feed the debate: that in CF table there is also the quantity 'sea_surface_height_above_geoid'. That could be a possibility too, I think? Cheers, Olivier. -Message d'origine- De : cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] De la part de Lowry, Roy K Envoyé : mercredi 27 janvier 2010 09:58 À : Jeff deLaBeaujardiere; cf-metadata@cgd.ucar.edu Cc : Mike Garcia Objet : Re: [CF-metadata] seeking CF name for total water column height Dear All, I think a new Standard Name 'sea_floor_depth_below_sea_surface' is what's needed here. My definition for this would be 'The vertical distance between the sea surface and the seabed at a given point in space and at a given instant in time or averaged over a time interval that is significantly less than a tidal cycle (1 hour or less).' This may seem complicated, but is needed to cover BPRs which do some averaging to smooth out waves. My take on 'height_above_sea_floor' would be as the z co-ordinate for something inside a water body. May be worth pointing out to Jeff that there is already 'sea_water_pressure_at_sea_floor' for BPR data that haven't been converted to depth. I've expressed this as a depth rather than as a height to be consistent with 'sea_floor_depth_below_sea_level' and so we don't end up with different terms for the same quantity depending upon whether one is looking upwards or downwards. Cheers, Roy. -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Jeff deLaBeaujardiere Sent: 26 January 2010 22:22 To: cf-metadata@cgd.ucar.edu Cc: Mike Garcia Subject: [CF-metadata] seeking CF name for total water column height Hello- I am a new subscriber. We are hoping to adopt CF names wherever possible in the context of the Integrated Ocean Observing System (IOOS) Sensor Observation Services (SOS). Not all phenomena we measure have immediately apparent CF names, however. We are using this URL as a reference: http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-table/current/cf-standard-name-table.html The first example is total water column height as derived from a bottom pressure recorder associated with a tsunami warning buoy. This is not sea_surface_height_above_reference_ellipsoid or _above_sea_level. It might be height_above_sea_floor but we're not really sure what that refers to (height of what?). Is there a standard name present or planned that is equivalent to total_water_column_height? Thanks for any information, Jeff DLB -- Jeff de La Beaujardière, 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.delabeaujardi...@noaa.gov ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- 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 Cliquez sur l'url suivante https://www.mailcontrol.com/sr/XSF3ayfb92zTndxI!oX7UtTXwRoU2H8X9MZg!!X+6h5uo0A89Yts6hMrboLqIZ6d9r4ZDktgx4ejfskgLULbMA== si ce message est indésirable (pourriel). ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] seeking CF name for total water column height
Any particular reason that you are biased for this name representing only a short-term value? Seems to me there is equally the need for a (measured or modeled) value that would be defined exactly the same way, but without the time qualifiers. In general, when CF has a measured observable, the name makes no statement about whether the variable has been measured instantaneously, or for 1 hour, or for one month. It's time-neutral. This has several advantages. I suggest either the same principle be applied here, or that the possibility of the longer-time-frame name be accommodated by adding a qualifier to the name associated with this definition. John On Jan 27, 2010, at 00:58, Lowry, Roy K wrote: Dear All, I think a new Standard Name 'sea_floor_depth_below_sea_surface' is what's needed here. My definition for this would be 'The vertical distance between the sea surface and the seabed at a given point in space and at a given instant in time or averaged over a time interval that is significantly less than a tidal cycle (1 hour or less).' This may seem complicated, but is needed to cover BPRs which do some averaging to smooth out waves. My take on 'height_above_sea_floor' would be as the z co-ordinate for something inside a water body. May be worth pointing out to Jeff that there is already 'sea_water_pressure_at_sea_floor' for BPR data that haven't been converted to depth. I've expressed this as a depth rather than as a height to be consistent with 'sea_floor_depth_below_sea_level' and so we don't end up with different terms for the same quantity depending upon whether one is looking upwards or downwards. Cheers, Roy. -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu ] On Behalf Of Jeff deLaBeaujardiere Sent: 26 January 2010 22:22 To: cf-metadata@cgd.ucar.edu Cc: Mike Garcia Subject: [CF-metadata] seeking CF name for total water column height Hello- I am a new subscriber. We are hoping to adopt CF names wherever possible in the context of the Integrated Ocean Observing System (IOOS) Sensor Observation Services (SOS). Not all phenomena we measure have immediately apparent CF names, however. We are using this URL as a reference: http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-table/current/cf-standard-name-table.html The first example is total water column height as derived from a bottom pressure recorder associated with a tsunami warning buoy. This is not sea_surface_height_above_reference_ellipsoid or _above_sea_level. It might be height_above_sea_floor but we're not really sure what that refers to (height of what?). Is there a standard name present or planned that is equivalent to total_water_column_height? Thanks for any information, Jeff DLB -- Jeff de La Beaujardière, 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.delabeaujardi...@noaa.gov ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- 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 -- I have my new work email address: jgrayb...@ucsd.edu -- John Graybeal mailto:jgrayb...@ucsd.edu phone: 858-534-2162 System Development Manager Ocean Observatories Initiative Cyberinfrastructure Project: http://ci.oceanobservatories.org Marine Metadata Interoperability Project: http://marinemetadata.org ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] seeking CF name for total water column height
I have no concern about whether this stream needs labeling. My concern is whether you are defining something in the definition which is in no way described by the label, and which will prevent that label being used for other variables in other streams. Put another way, what should the models that calculate the nominal sea_floor_depth_below_sea_surface -- or an averaged value longer than 1 hour -- call their values? John On Jan 27, 2010, at 12:54, Lowry, Roy K wrote: Hi John, Simple pragmatism. It's what a BPR data stream tends to contain and so it needs labelling. Cheers, Roy. From: John Graybeal [jbgrayb...@mindspring.com] Sent: 27 January 2010 16:41 To: Lowry, Roy K Cc: Jeff deLaBeaujardiere; cf-metadata@cgd.ucar.edu; Mike Garcia Subject: Re: [CF-metadata] seeking CF name for total water column height Any particular reason that you are biased for this name representing only a short-term value? Seems to me there is equally the need for a (measured or modeled) value that would be defined exactly the same way, but without the time qualifiers. In general, when CF has a measured observable, the name makes no statement about whether the variable has been measured instantaneously, or for 1 hour, or for one month. It's time-neutral. This has several advantages. I suggest either the same principle be applied here, or that the possibility of the longer-time-frame name be accommodated by adding a qualifier to the name associated with this definition. John On Jan 27, 2010, at 00:58, Lowry, Roy K wrote: Dear All, I think a new Standard Name 'sea_floor_depth_below_sea_surface' is what's needed here. My definition for this would be 'The vertical distance between the sea surface and the seabed at a given point in space and at a given instant in time or averaged over a time interval that is significantly less than a tidal cycle (1 hour or less).' This may seem complicated, but is needed to cover BPRs which do some averaging to smooth out waves. My take on 'height_above_sea_floor' would be as the z co-ordinate for something inside a water body. May be worth pointing out to Jeff that there is already 'sea_water_pressure_at_sea_floor' for BPR data that haven't been converted to depth. I've expressed this as a depth rather than as a height to be consistent with 'sea_floor_depth_below_sea_level' and so we don't end up with different terms for the same quantity depending upon whether one is looking upwards or downwards. Cheers, Roy. -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu ] On Behalf Of Jeff deLaBeaujardiere Sent: 26 January 2010 22:22 To: cf-metadata@cgd.ucar.edu Cc: Mike Garcia Subject: [CF-metadata] seeking CF name for total water column height Hello- I am a new subscriber. We are hoping to adopt CF names wherever possible in the context of the Integrated Ocean Observing System (IOOS) Sensor Observation Services (SOS). Not all phenomena we measure have immediately apparent CF names, however. We are using this URL as a reference: http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-table/current/cf-standard-name-table.html The first example is total water column height as derived from a bottom pressure recorder associated with a tsunami warning buoy. This is not sea_surface_height_above_reference_ellipsoid or _above_sea_level. It might be height_above_sea_floor but we're not really sure what that refers to (height of what?). Is there a standard name present or planned that is equivalent to total_water_column_height? Thanks for any information, Jeff DLB -- Jeff de La Beaujardière, 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.delabeaujardi...@noaa.gov ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- 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 -- I have my new work email address: jgrayb...@ucsd.edu -- John Graybeal mailto:jgrayb...@ucsd.edu phone: 858-534-2162 System Development Manager Ocean Observatories Initiative Cyberinfrastructure Project: http://ci.oceanobservatories.org Marine Metadata Interoperability Project: http://marinemetadata.org -- This message (and any attachments
[CF-metadata] seeking CF name for total water column height
Hello- I am a new subscriber. We are hoping to adopt CF names wherever possible in the context of the Integrated Ocean Observing System (IOOS) Sensor Observation Services (SOS). Not all phenomena we measure have immediately apparent CF names, however. We are using this URL as a reference: http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-table/current/cf-standard-name-table.html The first example is total water column height as derived from a bottom pressure recorder associated with a tsunami warning buoy. This is not sea_surface_height_above_reference_ellipsoid or _above_sea_level. It might be height_above_sea_floor but we're not really sure what that refers to (height of what?). Is there a standard name present or planned that is equivalent to total_water_column_height? Thanks for any information, Jeff DLB -- Jeff de La Beaujardière, 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.delabeaujardi...@noaa.gov ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
