Re: [CF-metadata] water level with/without datum
Hi all, When I reread my previous mail, I found it was very confused and also looked not nice with previous contributions like Roy's: it was not my intentions, sorry for that. Writing things too fast causes muddled and blurred discourse! If we consider the last proposal from Seth, does that mean that we could have two different possibilities for the same standard name? If yes, I am afraid we could raise a situation where one would have collocated satellite data to compare with in-situ data and: - In the satellite dataset, CF attribute would be sea_surface_height_above_.. - In the in-situ dataset, CF attribute would be water_body_surface_height_above.. ? (Or perhaps I haven't well understood) Olivier -Message d'origine- De : cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] De la part de Seth McGinnis Envoyé : samedi 27 février 2010 04:51 À : cf-metadata@cgd.ucar.edu Objet : Re: [CF-metadata] water level with/without datum Therefore I think we have to decide what to call the new names. Roy suggested water body. As I've said before, I would prefer sea/lake/river_water (or with some other punctuation) to water_body_water, because sea/lake/river_water is more self-explanatory, and the repetition of water in water_body_water is clumsy and possibly confusing. I can imagine someone not being sure how to parse water body water temperature when they first come across it. Instead of a prefix modifer, how about adding _body as a postfix modifier? So you could have sea_water_temperature for oceans and water_body_temperature for oceans, rivers, lakes, and other significant accumulations of liquid water. Cheers, Seth McGinnis NARCCAP Data Manager ISSE / ISP / IMAGe / CISL / NCAR (P.S.: Observation/tangent: It seems like this conundrum may be arising in part because the day-to-day meaning of the term water -- liquid H2O -- is at odds with the definition given in the standard name guidelines of water in all phases if not otherwise qualified. Were there a blank slate, I would suggest using the unqualified term to mean liquid water, in better alignment with its commonsense meaning, and coming up with a new term for the more restricted contexts where one needs to refer to all three phases. How frequently in current usage does the all phases sense differ fom the usual sense? Would it be worth considering a switch? That would be an alternate way around the issue of generic water bodies.) ___ 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/Y8JdOU4DsM7TndxI!oX7UvGHrMX8oTLhxXmnApiAmj9zdQJy4gJWXe3FyfcXLuoUBltZoDt4qRPbd8XIx2vetQ== 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] water level with/without datum
Dear Olivier - In the satellite dataset, CF attribute would be sea_surface_height_above_.. - In the in-situ dataset, CF attribute would be water_body_surface_height_above.. I believe that we have agreed to call the latter water_surface_height_above... (John's suggestion). Are you happy with that? I think this general name could be used for sea, lake or river, but we also keep the sea_surface_height for sea specifically. I think sea_surface_height is the name which should be used for both satellite altimetry and tide-gauge measurements (on the sea). It's the same geophysical quantity, whichever way it's measured, so it should have the same name. water_surface_height could equally be used for either measurement method, and is appropriate if the data are not just for the sea. This sidesteps the general issue of sea/lake/river terms. The use of surface in water_surface makes it clear enough where the water is. If someone is definitely asking for a standard name which refers to a property of water in in sea, lake or river in general, we can return to that discussion. Roy gave a use case, but I'm not sure if that's a definite need. At present, my own preference would be for the lengthy but clear phrase sea_or_lake_or_river. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Hi Nan, Using unqualified 'water' to signify water within a water body works for me. Cheers, Roy. -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Nan Galbraith Sent: 25 February 2010 16:47 To: Jonathan Gregory Cc: John Graybeal; cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] water level with/without datum Agreed, water_surface_height_above_x is perfect. And simple, as Jeff pointed out earlier this week. I think Roy's example is a relevant use case. Although he has not made a proposal, his data set requires either a new name of river_water_temperature, or a name which can be used for both sea and river. The existing name of sea_water_temperature is not sufficient for the case he described. Roy's example shows the need for a *single name* that can be used for both sea and river temperature, not different names, if I understand his description correctly. I'd like to extend the use of this prospective term to sub-surface water bodies, which, like rivers, don't always have clear boundaries. We have ROVs that travel from lakes and reservoirs through subsurface passages; I don't see any reason to (or reasonable way to) split up the measurements made by these instruments based on which side of an invisible line they're on at any given point. So, I think 'water' is far better than 'sea_lake_river_water'. There are several names that use the modifiers 'atmosphere', 'in_air' and 'surface' to indicate water that's not part of a water body. Does this imply that the unmodified term 'water' means water that's in a water body? The only names I can find that use plain 'water' seem to be sound_intensity and sound_pressure terms - I assume these refer to water in a water body? Is that enough of a precedent to suggest that water_temperature, _velocity, _salinity, etc etc could be standard names for properties of the water in bodies of water? Cheers - Nan water_surface_height_above_x seems to meet all the criteria. -- *** * 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] water level with/without datum
Dear Nan I think Roy's example is a relevant use case. Although he has not made a proposal, his data set requires either a new name of river_water_temperature, or a name which can be used for both sea and river. The existing name of sea_water_temperature is not sufficient for the case he described. Roy's example shows the need for a *single name* that can be used for both sea and river temperature, not different names, if I understand his description correctly. That's right. He needs a single name which covers sea and river. I don't see any reason to (or reasonable way to) split up the measurements made by these instruments based on which side of an invisible line they're on at any given point. Yes. In some applications it is artificial to distinguish between sea, lake, reservoir, river etc. There are several names that use the modifiers 'atmosphere', 'in_air' and 'surface' to indicate water that's not part of a water body. Does this imply that the unmodified term 'water' means water that's in a water body? The only names I can find that use plain 'water' seem to be sound_intensity and sound_pressure terms - I assume these refer to water in a water body? Is that enough of a precedent to suggest that water_temperature, _velocity, _salinity, etc etc could be standard names for properties of the water in bodies of water? I don't remember the intention of those standard names. I am surprised that they don't say sea or river if that's what they meant. I am sorry to be obstinate on this, but I don't think that it would be right to assume that water without any qualifier meant water that is part of a water body. As I said in a previous email, we always try to indicate the context explicitly in standard names, to make them self-describing. This use of water would be a kind of definition by omission, rather than explicitly. I think that our discussion so far indicates that we should keep the existing sea names, and add corresponding new names for water bodies in general (as and when they are requested). We can likewise add new sea names. Therefore I think we have to decide what to call the new names. Roy suggested water body. As I've said before, I would prefer sea/lake/river_water (or with some other punctuation) to water_body_water, because sea/lake/river_water is more self-explanatory, and the repetition of water in water_body_water is clumsy and possibly confusing. I can imagine someone not being sure how to parse water body water temperature when they first come across it. As Roy said, / could be a problem, although it's legal for netCDF. It does make the intention clearer, since / means or. It could be spelled out, at the cost of greater length, as sea_or_lake_or_river_water. best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Dear Jeff After more internal discussion we feel that the single name 'water_surface_height_above_reference_datum' would meet our needs admirably (i.e., no separate name for the station datum case). Very good. Is this an arbitrary local reference datum? I think that would be the right name, if so. If it's the geoid or some tide level, I think that should be indicated in the name. That's because quantities with these different datums do not differ by a constant, and could not be regarded as the same geophysical quantity, so should have different standard names. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Therefore I think we have to decide what to call the new names. Roy suggested water body. As I've said before, I would prefer sea/lake/river_water (or with some other punctuation) to water_body_water, because sea/lake/river_water is more self-explanatory, and the repetition of water in water_body_water is clumsy and possibly confusing. I can imagine someone not being sure how to parse water body water temperature when they first come across it. Instead of a prefix modifer, how about adding _body as a postfix modifier? So you could have sea_water_temperature for oceans and water_body_temperature for oceans, rivers, lakes, and other significant accumulations of liquid water. Cheers, Seth McGinnis NARCCAP Data Manager ISSE / ISP / IMAGe / CISL / NCAR (P.S.: Observation/tangent: It seems like this conundrum may be arising in part because the day-to-day meaning of the term water -- liquid H2O -- is at odds with the definition given in the standard name guidelines of water in all phases if not otherwise qualified. Were there a blank slate, I would suggest using the unqualified term to mean liquid water, in better alignment with its commonsense meaning, and coming up with a new term for the more restricted contexts where one needs to refer to all three phases. How frequently in current usage does the all phases sense differ fom the usual sense? Would it be worth considering a switch? That would be an alternate way around the issue of generic water bodies.) ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Dear John et al. water_surface_height_above_x seems to meet all the criteria. I agree, this would be fine for Jeff's need. Thanks for suggesting it. It is like sea_surface_height_above_X, which already exists, and surface disambiguates it. It does not solve the general problem, illustrated by Roy's use case. We will not be able to use surface for properties measured *within* the water, such as temperature, velocity, etc., as that would be confusing. But, as is our usual habit, we can postpone trying to solve that problem until someone definitely requests a standard name which raises it. In that case, we'd probably have to return to the sea/lake/river debate. I could handle sea+lake+river but it doesn't thrill me, because of (a) special characters which can have unintended consequences for times now and yet to come, (b) 'sea' is not self-explanatory until you know it really means ocean (in some local dialects) and excludes inland seas (or maybe not?), and (c) awkwardness. Not a preference but if all others get ruled out, there we'd be. Yes, I actually agree. As for (a), maybe sea_lake_river would be better. Sea means ocean or sea in CF names - any body of water which is connected to the world ocean. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Agreed, water_surface_height_above_x is perfect. And simple, as Jeff pointed out earlier this week. I think Roy's example is a relevant use case. Although he has not made a proposal, his data set requires either a new name of river_water_temperature, or a name which can be used for both sea and river. The existing name of sea_water_temperature is not sufficient for the case he described. Roy's example shows the need for a *single name* that can be used for both sea and river temperature, not different names, if I understand his description correctly. I'd like to extend the use of this prospective term to sub-surface water bodies, which, like rivers, don't always have clear boundaries. We have ROVs that travel from lakes and reservoirs through subsurface passages; I don't see any reason to (or reasonable way to) split up the measurements made by these instruments based on which side of an invisible line they're on at any given point. So, I think 'water' is far better than 'sea_lake_river_water'. There are several names that use the modifiers 'atmosphere', 'in_air' and 'surface' to indicate water that's not part of a water body. Does this imply that the unmodified term 'water' means water that's in a water body? The only names I can find that use plain 'water' seem to be sound_intensity and sound_pressure terms - I assume these refer to water in a water body? Is that enough of a precedent to suggest that water_temperature, _velocity, _salinity, etc etc could be standard names for properties of the water in bodies of water? Cheers - Nan water_surface_height_above_x seems to meet all the criteria. -- *** * 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] water level with/without datum
Hello Jonathan, I have concerns about having separate names for river, lake and sea. If you have them for height, then the logic would extend to temperature. I have temperature data from a boat that started in the North Sea, went up the Humber and then up to the navigable limit of the Yorkshire Ouse. I would much prefer a single Standard Name across the whole dataset. My suggestion of 'water body' as the generic term didn't get any reaction. Was that acceptance or did nobody notice it? Cheers, Roy. -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Jonathan Gregory Sent: 22 February 2010 19:02 To: Jeff deLaBeaujardiere Cc: Andrea Hardy; cf-metadata@cgd.ucar.edu Subject: [CF-metadata] water level with/without datum Dear Jeff et al About water_level_with|above_reference_datum water_level_without_reference_datum I'd like to make some suggestions: * Since we don't have a convenient word for river, lake or sea, perhaps we should have separate names for each of them i.e. sea_surface_height, lake_surface_height and river_surface_height. All these terms are in use, often in connection with altimetry. Obviously the same duplication (or triplication) could occur with other sea-related names, but we have not had a great demand for terms related to lakes and rivers up to now. Even if we did, it would not be an unmanageable expansion of the standard name table. There are currently 284 standard names containing the word sea. * If the datum is an arbitrary local benchmark, then I think a name of sea/lake/river_surface_height_above_reference_datum would be fine. If the datum itself needs to be located, we could have standard names for that such as sea/lake/river_surface_reference_datum_altitude. * If the datum is a quantity which could be regarded as a continuous function of location, I think it should be identified in the standard name, as in the existing sea_surface_height_above_geoid. Other standard names would thus be needed for sea_surface_height_above_mean_high_water etc. We also have an existing name of sea_surface_height_above_reference_ellipsoid. Here, the ellipsoid is not identified, but it can be with other CF metadata. I think that's OK because the geophysical intention of the reference ellipsoid is always the same, so this is in a sense a matter of measurement rather than the quantity itself. By contrast, mean high water is a different geophysical concept from the geoid. 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] water level with/without datum
Dear Roy I have concerns about having separate names for river, lake and sea. If you have them for height, then the logic would extend to temperature. I have temperature data from a boat that started in the North Sea, went up the Humber and then up to the navigable limit of the Yorkshire Ouse. I would much prefer a single Standard Name across the whole dataset. I share that concern, but I didn't have a use-case where it would be a problem to have separate names, so thanks for that. My suggestion of 'water body' as the generic term didn't get any reaction. Was that acceptance or did nobody notice it? I noticed it, yes, thanks! It is a correct generic term, of course, but I feel it would cause a loss of clarity to replace sea with water body in existing standard names e.g. water_body_surface_height, water_body_water_temperature, water_body_water_speed and water_body_ice_thickness are all unfamiliar terms, whereas sea_surface_height, sea_water_temperature, sea_water_speed and sea_ice_thickness are all recognisable. In the particular case of Jeff's, water body surface height is not a term that Google finds, whereas sea surface height, lake surface height and river surface height do all exist. More cumbersome than water body, but clearer I think, would be to use the phrase sea/lake/river (I think / is a permitted character) e.g. sea/lake/river_surface_height, sea/lake/river_water_temperature. We could provide such names of this type as are requested, for generic uses like yours, but keep the sea names as well. In a case such as yours, would it be acceptable to use sea all the time, even when it's a river? Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Hi Roy, Would simply inventing an artificial new term to represent sea+lakes+rivers be an option here? Presumably, back in the day, there was no word for a land-locked body of fresh water so someone thought, I know, I'll call it a 'lake'. Or whatever the latin/greek equivalent was back then! So we might choose, say, the word 'sorl', this being an acronym for seas, oceans, rivers and lakes. Sure that's not very pretty but no doubt someone can think of a better word. Answers on an e-postcard... Regards, Phil -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Lowry, Roy K Sent: 23 February 2010 09:06 To: Jonathan Gregory Cc: Andrea Hardy; cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] water level with/without datum Hello again, I wouldn't recommend using '/' in a string, such as a Standard Name, that could potentially be incorporated into a URL. I think using 'sea' as defined shorthand for 'river/lake/sea' has been suggested before. I certainly have no problem with it as long as that information is included in the definition. Cheers, Roy. -Original Message- From: Jonathan Gregory [mailto:jonat...@met.reading.ac.uk] On Behalf Of Jonathan Gregory Sent: 23 February 2010 08:47 To: Lowry, Roy K Cc: Jeff deLaBeaujardiere; Andrea Hardy; cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] water level with/without datum Dear Roy I have concerns about having separate names for river, lake and sea. If you have them for height, then the logic would extend to temperature. I have temperature data from a boat that started in the North Sea, went up the Humber and then up to the navigable limit of the Yorkshire Ouse. I would much prefer a single Standard Name across the whole dataset. I share that concern, but I didn't have a use-case where it would be a problem to have separate names, so thanks for that. My suggestion of 'water body' as the generic term didn't get any reaction. Was that acceptance or did nobody notice it? I noticed it, yes, thanks! It is a correct generic term, of course, but I feel it would cause a loss of clarity to replace sea with water body in existing standard names e.g. water_body_surface_height, water_body_water_temperature, water_body_water_speed and water_body_ice_thickness are all unfamiliar terms, whereas sea_surface_height, sea_water_temperature, sea_water_speed and sea_ice_thickness are all recognisable. In the particular case of Jeff's, water body surface height is not a term that Google finds, whereas sea surface height, lake surface height and river surface height do all exist. More cumbersome than water body, but clearer I think, would be to use the phrase sea/lake/river (I think / is a permitted character) e.g. sea/lake/river_surface_height, sea/lake/river_water_temperature. We could provide such names of this type as are requested, for generic uses like yours, but keep the sea names as well. In a case such as yours, would it be acceptable to use sea all the time, even when it's a river? Best wishes Jonathan -- 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 ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Hi Phil, Jonathan's argument against 'water body' was that it was not as well-known as 'sea'. I think that the argument applies even more strongly to 'sorl'. Cheers, Roy. -Original Message- From: Bentley, Philip [mailto:philip.bent...@metoffice.gov.uk] Sent: 23 February 2010 09:25 To: Lowry, Roy K Cc: cf-metadata@cgd.ucar.edu Subject: RE: [CF-metadata] water level with/without datum Hi Roy, Would simply inventing an artificial new term to represent sea+lakes+rivers be an option here? Presumably, back in the day, there was no word for a land-locked body of fresh water so someone thought, I know, I'll call it a 'lake'. Or whatever the latin/greek equivalent was back then! So we might choose, say, the word 'sorl', this being an acronym for seas, oceans, rivers and lakes. Sure that's not very pretty but no doubt someone can think of a better word. Answers on an e-postcard... Regards, Phil -Original Message- From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Lowry, Roy K Sent: 23 February 2010 09:06 To: Jonathan Gregory Cc: Andrea Hardy; cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] water level with/without datum Hello again, I wouldn't recommend using '/' in a string, such as a Standard Name, that could potentially be incorporated into a URL. I think using 'sea' as defined shorthand for 'river/lake/sea' has been suggested before. I certainly have no problem with it as long as that information is included in the definition. Cheers, Roy. -Original Message- From: Jonathan Gregory [mailto:jonat...@met.reading.ac.uk] On Behalf Of Jonathan Gregory Sent: 23 February 2010 08:47 To: Lowry, Roy K Cc: Jeff deLaBeaujardiere; Andrea Hardy; cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] water level with/without datum Dear Roy I have concerns about having separate names for river, lake and sea. If you have them for height, then the logic would extend to temperature. I have temperature data from a boat that started in the North Sea, went up the Humber and then up to the navigable limit of the Yorkshire Ouse. I would much prefer a single Standard Name across the whole dataset. I share that concern, but I didn't have a use-case where it would be a problem to have separate names, so thanks for that. My suggestion of 'water body' as the generic term didn't get any reaction. Was that acceptance or did nobody notice it? I noticed it, yes, thanks! It is a correct generic term, of course, but I feel it would cause a loss of clarity to replace sea with water body in existing standard names e.g. water_body_surface_height, water_body_water_temperature, water_body_water_speed and water_body_ice_thickness are all unfamiliar terms, whereas sea_surface_height, sea_water_temperature, sea_water_speed and sea_ice_thickness are all recognisable. In the particular case of Jeff's, water body surface height is not a term that Google finds, whereas sea surface height, lake surface height and river surface height do all exist. More cumbersome than water body, but clearer I think, would be to use the phrase sea/lake/river (I think / is a permitted character) e.g. sea/lake/river_surface_height, sea/lake/river_water_temperature. We could provide such names of this type as are requested, for generic uses like yours, but keep the sea names as well. In a case such as yours, would it be acceptable to use sea all the time, even when it's a river? Best wishes Jonathan -- 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 -- 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] water level with/without datum
Hi Roy, For sure, I wasn't proposing use of the word 'sorl', that was merely an examplar. My argument was that since there appears to be no existing term for what you want to describe - at least none without overloaded meaning(s) - then just invent a completely new word. So, yes, by its very nature it wouldn't be well-known on day 1! Cheers, Phil -Original Message- From: Lowry, Roy K [mailto:r...@bodc.ac.uk] Sent: 23 February 2010 11:19 To: Bentley, Philip Cc: cf-metadata@cgd.ucar.edu Subject: RE: [CF-metadata] water level with/without datum Hi Phil, Jonathan's argument against 'water body' was that it was not as well-known as 'sea'. I think that the argument applies even more strongly to 'sorl'. Cheers, Roy. -Original Message- From: Bentley, Philip [mailto:philip.bent...@metoffice.gov.uk] Sent: 23 February 2010 09:25 To: Lowry, Roy K Cc: cf-metadata@cgd.ucar.edu Subject: RE: [CF-metadata] water level with/without datum Hi Roy, Would simply inventing an artificial new term to represent sea+lakes+rivers be an option here? Presumably, back in the day, there was no word for a land-locked body of fresh water so someone thought, I know, I'll call it a 'lake'. Or whatever the latin/greek equivalent was back then! So we might choose, say, the word 'sorl', this being an acronym for seas, oceans, rivers and lakes. Sure that's not very pretty but no doubt someone can think of a better word. Answers on an e-postcard... ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Dear Stephen The issue here is that water doesn't only exist in these bodies of water viz seas, lakes and river. It also exists in the atmosphere and the ground. For this reason we don't have a standard name of just water temperature, for instance. We could define aqua to mean sea, lake or river, but this is not really any more self-explanatory than using an abbreviation, I'd say. Roy pointed out that / would be a dangerous character to use, so I'd next suggest sea+lake+river. I prefer + to - because - looks like _, and it's terribly confusing to have a mixture of - and _. I really would prefer defining sea to mean sea, lake or river but not everyone who's given an opinion would support that, and I agree that it's not really self-describing - it would be new jargon. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Dear CF group: Thank you for your time in discussing this matter. I would counsel you *not* to make wholesale changes to existing names just because IOOS needs names for water levels that may or may not be measured in the ocean! Replacing 'sea_' with something else seems like it would break much existing code. Adding some names should be mostly harmless. For the specific case of water-level measurement devices, I think the term water_level_* is better, applied generically regardless of oceanic, lacustrine or riverine environment, for the following reasons. * There is no other generic name, and inventing one like SLR or sea+lake+river seems contrived. * Every use of sea_level I can find in the CF name list refers to sea level as a semi-constant reference point rather than as an instantaneous measurement. Indeed, a comment used repeatedly in the CF table is that sea_level means mean sea level, which is close to the geoid in sea areas. Therefore, separate names for sea_level_*, lake_level_ and river_level_* do not seem appropriate. * Yes, there is water in the atmosphere and underground. CF already seems to qualify those uses with terms like 'atmosphere', 'cloud' and 'in air.' Therefore, it does not seem necessary to qualify 'water' as being on the surface--simply retain the existing non-surface qualifiers. If you later need a name to refer to the level of water in an underground aquifer or something, then create one. Regarding the Use Case of measuring temperature in the sea and then continuing the trajectory upriver: there currently do not exist water_temperature names other than sea_water_temperature, so the Use Case is not satisfied at present. Perhaps in future CF could define additional generic names like water_temperature that may have specializations such as sea_water_temperature and fresh_water_temperature, but this can be done later and independently of the existing actual use case of water level measurements. Cheers, 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
Re: [CF-metadata] water level with/without datum
Dear Jeff Thanks for your email. I appreciate your arguments, which are very reasonable, but I don't agree with them so far. Replacing 'sea_' with something else seems like it would break much existing code. Adding some names should be mostly harmless. Yes, adding names is better. We can resolve this by keeping sea to mean sea, and adding some other ones to refer to sea, lake or river, as requested. We agree on that point. For the specific case of water-level measurement devices, I think the term water_level_* is better, applied generically regardless of oceanic, lacustrine or riverine environment, for the following reasons. * There is no other generic name, and inventing one like SLR or sea+lake+river seems contrived. Contrived, yes, but sea+lake+river is certainly explicit and self-explanatory, isn't it? Standard names are contrived to explain what they mean, rather than being the terms used most commonly (although some of them are common terms). The term name is a bit misleading. They are not names, in most cases. They are answers to the question, What does that mean?, when a term is used. * Every use of sea_level I can find in the CF name list refers to sea level as a semi-constant reference point rather than as an instantaneous measurement. Indeed, a comment used repeatedly in the CF table is that sea_level means mean sea level, which is close to the geoid in sea areas. Therefore, separate names for sea_level_*, lake_level_ and river_level_* do not seem appropriate. Yes, sea_level refers to a fixed level, like geoid, but the quantity you are referring to as water_level is more like sea_surface_height, which is a time-varying level, and is referred to a fixed level. I am proposing of sea+lake+river_surface_height_above_X for your water level, if it's not the sea. * Yes, there is water in the atmosphere and underground. CF already seems to qualify those uses with terms like 'atmosphere', 'cloud' and 'in air.' Therefore, it does not seem necessary to qualify 'water' as being on the surface--simply retain the existing non-surface qualifiers. If you later need a name to refer to the level of water in an underground aquifer or something, then create one. That gives a special status to water on the surface. CF names attempt to deal even-handedly with all geophysical quantities. Such an argument would mean that, in the first place, we would have used the plain name temperature to mean air temperature (since we started with atmospheric models, mostly), and later added sea_water_temperature. That would have been inconsistent and I believe that such inconsistencies would make standard names less satisfactory in practice. In general, we have tried to include some context in standard names. Regarding the Use Case of measuring temperature in the sea and then continuing the trajectory upriver: there currently do not exist water_temperature names other than sea_water_temperature, so the Use Case is not satisfied at present. Perhaps in future CF could define additional generic names like water_temperature that may have specializations such as sea_water_temperature and fresh_water_temperature, but this can be done later and independently of the existing actual use case of water level measurements. I think Roy's example is a relevant use case. Although he has not made a proposal, his data set requires either a new name of river_water_temperature, or a name which can be used for both sea and river. The existing name of sea_water_temperature is not sufficient for the case he described. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
On Feb 23, 2010, at 06:33, Jonathan Gregory wrote: Contrived, yes, but sea+lake+river is certainly explicit and self- explanatory, isn't it? Standard names are contrived to explain what they mean, rather than being the terms used most commonly (although some of them are common terms). The term name is a bit misleading. They are not names, in most cases. They are answers to the question, What does that mean?, when a term is used. water_surface_height_above_x seems to meet all the criteria. It answers what does that mean? It is explicit and self-explanatory (and even reasonably short). Thanks to the 'surface' term, it can not be confused with 'atmospheric surface water height' (what would that mean?). The fact that it also applies to underground water is a non-issue, scientifically speaking, and in my mind is advantageous, because it is equally meaningful in that context. (Two data sets with this term can be compared, regardless of whether the water is underground or not -- the x normalized the reference, as does the location.) I can even construct a valid use case (for an AUV or hydro model) that is the analog of Roy's, in the case of underground streams feeding into oceans or rivers. I could handle sea+lake+river but it doesn't thrill me, because of (a) special characters which can have unintended consequences for times now and yet to come, (b) 'sea' is not self-explanatory until you know it really means ocean (in some local dialects) and excludes inland seas (or maybe not?), and (c) awkwardness. Not a preference but if all others get ruled out, there we'd be. John ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Dear John Sorry not to be clear. My main point is that sea_surface_height is an existing term which is customarily used to refer to the level of the water surface in the open ocean. I am arguing that, at the coast, the level of the sea water surface is really the same quantity as sea_surface_height away from the coast, and so it should have the same name. Then that raises the question of what to call the level of the water surface when it is a lake or a river but not the sea. We could have standard names using the phrases lake_surface_height and river_surface_height. That would be fine, except that the distinction may in some cases become inconvenient and arbitrary, as you have to decide exactly when it is one or another. It would be convenient to use the same word for all of them. I don't think it's such a good idea to solve this by dropping sea and calling it just water. Although you are right that the exact term water_level might not be needed in the atmosphere and the ground (though I suppose something like it might be used for ground water), I think it is preferable to use a term which includes the context. We try to make the standard names as informative and self-explanatory as we can, so we don't use just the word water without indicating somehow where the water is in the Earth system. For instance, we do not have a standard name of water content because the context is not clear. We have names such as atmosphere_water_content and soil_frozen_water_content. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
[CF-metadata] water level with/without datum
Thank you for the discussion and current status regarding sea_floor_depth_below_sea_surface as a new standard name. I have changed the subject line of this email to focus on the other names we discussed. I have also CCed our local water level expert (Andrea Hardy from NOAA CO-OPS); my replies are based on limited knowledge. alison.pamm...@stfc.ac.uk wrote: 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. I suppose you mean the latter name could be something like water_level_relative_to_tide_gauge_zero ? I believe that at NOAA we use the term station datum to refer to measurements relative only to the station (which might be a tide gauge or not), so perhaps one of these would be better: water_level_relative_to_station_datum water_level_above_station_datum I like the use of the word above because it indicates the sign of the value, but that's just a personal preference. 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. My understanding is that water level stations may be associated with rivers or the US Great Lakes, so sea surface would not be ideal. 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 Possible datums include at least International Great Lakes Datum (IGLD), mean high water (MHW), mean lower low water (MLLW), mean sea level (MSL), and NAVD88. I believe our preference would be *not* to include the datum name in the standard name, so that the user can request the datum of their choice. Andrea: I see that on your server Station Datum is among the choices. Are you sure it wouldn't be better to have a single name like water_level_relative_to_datum, with station datum merely being one of the options? Regarding the definitions, do both quantities average out the effects of waves? I don't know. Andrea? Regards to all from snowy Washington, 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
Re: [CF-metadata] water level with/without datum
Dear Jeff, Alison et al. Like Alison, I prefer sea_surface_height to water_level, because it's really the same geophysical quantity at the coast and far from the coast, isn't it. It seems awkward to me to say that the satellite altimeter measures SSH, while a tide gauge measures water level. The altimeter comes right up to the coast (in principle), so where is the distinction? Also, water_level is rather like sea_level, which is the name of a special surface i.e. mean sea level, whereas SSH is the name of time-varying quantity. I tend to think that geophysically different datums imply different geophysical quantities and standard names. The reference surface might also be time- dependent, in a different way (in general, more slowly) from the SSH; it's not a constant offset. There is some vagueness about this; some of the reference surfaces might be different estimates of the same thing e.g. different geoids and different reference ellipsoids. In that case we could use the same stdname, but we ought to use other attributes to be more precise, when necessary. But I don't think the lowest tide level, the mean high water, the (mean) sea level etc. should be regarded as the same reference surface. They're all different. Having a dozen different SSH standard names would be OK, I'd say. As for sea, lake and river - this is a vexed question we have never resolved! If only there were a simple word which meant any of the three! At the moment, we only have sea names. A possibility is to define sea to mean sea, lake or river, in CF standard names; obviously that could be confusing. We could replace sea (almost) everywhere with e.g. slr, which would not be self- explanatory, but it would force the user to look it up, and so it would not be confusing. (We do use a few other abbreviations e.g. toa and lwe.) e.g. sea_water_temperature - slr_water_temperature. I think that would be a reasonable solution, but there are probably better ones. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Jonathan Gregory wrote: As for sea, lake and river - this is a vexed question we have never resolved! If only there were a simple word which meant any of the three! That's why 'water_' seems preferable, in my view. Cheers, Jeff DLB ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
Dear Jeff As for sea, lake and river - this is a vexed question we have never resolved! If only there were a simple word which meant any of the three! That's why 'water_' seems preferable, in my view. Unfortunately water occurs not just in the sea, lakes and rivers, but also in the atmosphere and the ground. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] water level with/without datum
The term 'water_' is preferable to me too. When this liquid occurs underground, it still is appropriate to measure this quantity (and temperature, and other things). And when it occurs in the atmosphere, I don't think the term has any meaning -- measuring the height of atmospheric water is a conundrum at best; if the term's meaning is problematic, then define its meaning in that special case, and everything is consistent and meaningful with the most intuitive term available. john On Feb 12, 2010, at 13:53, Jonathan Gregory wrote: Dear Jeff As for sea, lake and river - this is a vexed question we have never resolved! If only there were a simple word which meant any of the three! That's why 'water_' seems preferable, in my view. Unfortunately water occurs not just in the sea, lakes and rivers, but also in the atmosphere and the ground. Best wishes Jonathan ___ 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
