Just a data point: Back in the day, I was told (on-list I thought) that sea_surface_temperature was effectively deprecated, at least for measurements. I understood that to be the reason for the explicit language that it was _not_ any of the other concepts -- just to make clear people should not be using it.
john -------------------------------------- John Graybeal [email protected] On Mar 7, 2016, at 17:47, Karl Taylor <[email protected]> wrote: > Dear Peter, Craig and all, > > For observations I am not arguing that all the different ocean temperature > definitions aren't needed. In describing observations I understand that skin > and surface temperature are not identical. My statement was that by > construction (almost all) current models assume that the temperature is > vertically uniform (i.e., the water is perfectly mixed and homogeneous) > throughout the upper most layer, so in *those* models the statement that the > "sea_surface_temperature" is "not the skin or interface temperature" is > *wrong*. > > The CF standard name description of "sea_surface_temperature" is somewhat > vague by design: "the temperature of sea water near the surface". Because it > is vague, it *could* defensibly be used to represent any more precisely > defined near-surface temperature, including "sea_surface_skin_temperature", > "sea_surface_subskin_temperature", or "sea_surface_foundation_temperature". > > Even for observations it would be wrong to say "sea water near the surface > is not the skin temperature". > > Since skin temperature is near the surface and sea_surface_temperature is > vague, it might in fact be the same as skin temperature (e.g., if > sea_surface_temperature in fact recorded the conductive diffusion-dominated > sub-layer at a depth of approximately 10-20 micrometers below the air-sea > interface). Again, usually in models, sea_surface_temperature most > emphatically does provide the model's best (only!) estimate of skin > temperature. > > If the description were changed to read: > "It is the temperature of sea water near the surface (including the part > under sea-ice, if any), and not necessarily the skin temperature". > I would be happy. > > Better yet, why not include in the discussion the following points: > > 1) surface temperature, sea_surface_temperature, > sea_surface_skin_temperature, sea_surface_subskin_temperature, and > sea_surface_foundation_temperature are all terms that might apply to the > temperature of sea water. > 2) When the temperature represents a horizontal spatial average, > surface_temperature represents the mean of the temperature over all surface > types in the domain, whereas the other temperatures do not. > 3) The sea_surface_temperature is imprecise because it represents a > near-surface temperature sampled within (or averaged over) the portion of the > column extending from the surface down to perhaps several meters. In many > ocean models, the temperature does not vary in that portion of the column so > sea_surface_temperature might be the appropriate standard_name. Note that in > this case, if part of the horizontal domain represented by this temperature > is under sea ice, the temperature would not be the same as > surface_temperature (which would include contributions from the surface of > the sea ice). > 4) The other CF standard names for ocean temperatures have more precise > definitions, and so those names should be used whenever they apply. > > best regards, > Karl > > > > On 3/7/16 7:06 AM, Peter Minnett wrote: >> Dear Alison, Craig, Karl et al., >> >> I have refrained from entering this discussion until now as Craig has made >> the points carefully and succinctly. But I think there's a fundamental issue >> at stake about what these definitions are for. >> >> My view is that definitions such as these are intended to provide a >> framework for communication that accurately but briefly represents our best >> understanding of the physics of the upper ocean and lower atmosphere. Thus, >> the definitions should not be constrained, or adapted, to reflect our >> current measurement or modelling capabilities as these, we expect, will >> improve with time. If, at some point in the future, we learn something new >> about how the thermal structure of the upper ocean behaves, then maybe the >> definitions will have to be revised, but for now I believe our definitions >> should be based on our understanding of the physical behavior of sea water >> near the air-sea interface. And this is what we tried to achieve with the >> GHRSST definitions. >> >> Best regards, >> >> Peter >> >> -------------------------------------------------------- >> Peter J. Minnett >> Professor, Department of Ocean Sciences >> Speaker, RSMAS School Council. >> Rosenstiel School of Marine and Atmospheric Science >> University of Miami >> 4600 Rickenbacker Causeway >> Miami, FL 33149-1031, USA >> >> Chairman, Science Team of the Group for High Resolution Sea-Surface >> Temperature (GHRSST) >> >> Tel: +1 (305) 421-4104 Fax: +1 (305) 421-4696 >> email: [email protected] >> http://www.rsmas.miami.edu/people/faculty-index/?p=peter-minnett >> https://www.ghrsst.org/ >> >> >> >> >> >> On 3/7/2016 6:41 AM, [email protected] wrote: >>> Dear Craig and Karl, >>> >>> Thanks both for your comments. It is clear that we need some more >>> discussion on this topic. I will be making an update to the standard name >>> table tomorrow but will defer any changes to the sea surface temperature >>> names until we can all agree a position on this. >>> >>> Best wishes, >>> Alison >>> >>> ------ >>> Alison Pamment Tel: >>> +44 1235 778065 >>> Centre for Environmental Data Analysis Email: >>> [email protected] >>> STFC Rutherford Appleton Laboratory >>> R25, 2.22 >>> Harwell Campus, Didcot, OX11 0QX, U.K. >>> >>> >>> From: Craig Donlon [mailto:[email protected]] >>> Sent: 07 March 2016 02:18 >>> To: Pamment, Alison (STFC,RAL,RALSP) >>> Cc: [email protected]; [email protected]; Kenneth Casey; Peter >>> Minnett; Anne O'Caroll; Edward Armstrong >>> Subject: Re: [CF-metadata] Confusing skin temperature and interface >>> temperature >>> >>> Dear Alison and Karl: >>> >>> Thanks for the discussion here. The key issue is that model teams need to >>> be more precise as to which SST variable is being used. As more advanced >>> systems begin to fully couple ocean and atmosphere, begin to perform >>> radiance assimilation etc the need for each of the different SST variables >>> becomes readily apparent. >>> >>> I would not like to see any of the current CF SST definitions watered down >>> in the manner proposed. But rather to ask Karl to define what he means by >>> SST in the modelling context that he is working? >>> >>> Then we may hope to resolve the issue efficiently. >>> >>> Regards >>> Craig >>> >>> -- >>> *** Sent from my iPhone *** >>> -- >>> Dr Craig Donlon >>> Sentinel-3 Mission Scientist, >>> Principal Scientist for Oceans and Ice >>> European Space Agency/ESTEC >>> Keplerlaan 1, 2201 AZ >>> Noordwijk >>> The Netherlands >>> >>> >>> e: [email protected] >>> t: +31 (0)715 653687 >>> f: +31 (0)715 655675 >>> m: +31 (0)627 013244 >>> Skype: crazit >>> >>> On 3 Mar 2016, at 19:53, <[email protected]> >>> <[email protected]> wrote: >>> >>> Dear Karl, >>> >>> Thanks for your comments on this. Clearly we need to get this right before >>> I make any changes in the standard name table. >>> >>> I recall that the sea surface skin, subskin and foundation temperatures >>> were introduced primarily to describe satellite radiometer data because the >>> existing sea_surface_temperature name was too vague. I have the impression >>> that modellers sometimes use the word “skin” as being synonymous with the >>> interface at the bottom of the atmosphere and I think that was probably the >>> intention behind its use in the current definition. By contrast, the >>> observational community have a very specific definition for the sea skin: >>> “the conductive diffusion-dominated sub-layer at a depth of approximately >>> 10 - 20 micrometers below the air-sea interface”. So I think there is scope >>> for some confusion here since the more specific sea surface temperature >>> names were introduced. >>> >>> As far as standard name definitions are concerned, the main thing is to >>> ensure we provide clear guidance as to when a particular name should be >>> used and to explain the relationships between similar names. I take your >>> point that some models may be deliberately formulated to have >>> sea_surface_temperature (by which I assume you mean the top layer of the >>> model) the same as the interface temperature. I assume you would still >>> label it with a standard name of sea_surface_temperature, even though in >>> this case it would be directly comparable with a variable with standard >>> name surface_temperature and we should probably explain that in the >>> definition. >>> >>> Do models ever output variables that you would actually want label as >>> “skin”, “subskin” or “foundation” temperatures (as defined in the existing >>> standard names)? If not, then perhaps it is best to simply note in the >>> definition that the other names exist and that they have very specific >>> definitions. This avoids the issue around the word “skin”. >>> >>> These points would then lead to a definition something like the following: >>> ‘Sea surface temperature is usually abbreviated as "SST". It is the >>> temperature of sea water near the surface (including the part under >>> sea-ice, if any), and is not necessarily the same as the interface >>> temperature at the bottom of the atmosphere, whose standard name is >>> surface_temperature. Some models are formulated such that >>> sea_surface_temperature and surface_temperature are the same in ice free >>> sea areas. The standard names sea_surface_skin_temperature, >>> sea_surface_subskin_temperature and sea_surface_foundation_temperature can >>> be used to describe the temperature in specific layers close to the sea >>> surface and are often used to describe satellite observations. For the >>> temperature of sea water at a particular depth or layer, a standard name of >>> sea_water_temperature with a vertical coordinate axis should be used.’ >>> >>> Does that sound OK? Does it include all the necessary information? >>> >>> Best wishes, >>> Alison >>> >>> ------ >>> Alison Pamment Tel: >>> +44 1235 778065 >>> Centre for Environmental Data Analysis Email: >>> [email protected] >>> STFC Rutherford Appleton Laboratory >>> R25, 2.22 >>> Harwell Campus, Didcot, OX11 0QX, U.K. >>> >>> >>> From: CF-metadata [mailto:[email protected]] On Behalf Of >>> Karl Taylor >>> Sent: 02 March 2016 20:26 >>> To: [email protected] >>> Subject: Re: [CF-metadata] Confusing skin temperature and interface >>> temperature >>> >>> Dear Alison and all, >>> >>> For "sea_surface_temperature", there is a problem stating definitively that >>> it is "not the skin or interface temperature". In most models the skin and >>> interface temperatures over ice-free (i.e., open) ocean are indeed the same >>> as sea_surface_temperature (by construction). I think it would be more >>> accurate (and less misleading) to say it is "not *necessarily* the skin or >>> interface temperature". You could also add to the list >>> "sea_surface_foundation_temperature" here because in models it too is often >>> the same as sea_surface_temperature". Models are evolving, so this might >>> not indefinitely be the case. >>> >>> thanks, >>> Karl >>> >>> >>> >>> On 3/2/16 9:40 AM, [email protected] wrote: >>> Dear Martin, All, >>> >>> No objections have been received to the proposed definition change and it >>> is now accepted for publication in the standard name table. >>> >>> The name will in future appear as: >>> sea_surface_temperature (canonical units: K) >>> ‘Sea surface temperature is usually abbreviated as "SST". It is the >>> temperature of sea water near the surface (including the part under >>> sea-ice, if any), not the skin or interface temperature, whose standard >>> names are sea_surface_skin_temperature and surface_temperature, >>> respectively. For the temperature of sea water at a particular depth or >>> layer, a data variable of sea_water_temperature with a vertical coordinate >>> axis should be used.’ >>> >>> In response to Martin’s proposal I received an email from Craig Donlon >>> (original proposer of many of the current sea_surface_X_temperature names). >>> Craig and his team support the Martin’s proposal and additionally point out >>> an error that occurs in the definition of the following names: >>> sea_surface_skin_temperature >>> sea_surface_subskin_temperature >>> in which the first sentence reads “The surface called "surface" means the >>> lower boundary of the atmosphere” even though the temperatures are not in >>> fact measured at the sea-air boundary. The suggestion is to delete the >>> initial sentence from the definitions. I note also that a similar situation >>> currently exists with the standard name sea_surface_foundation_temperature >>> even though that temperature generally refers to a depth of 1 – 5 m below >>> the sea surface. >>> >>> I agree with Craig that the sentence should be deleted. I think it was >>> probably included by accident because most “surface” standard names do >>> indeed refer to the interface between the bottom of the atmosphere and >>> whatever lies beneath. I plan to remove the sentence from the definitions >>> of these three names at the next standard name table update unless any >>> objections are received in the meantime. >>> >>> Best wishes, >>> Alison >>> >>> ------ >>> Alison Pamment Tel: >>> +44 1235 778065 >>> Centre for Environmental Data Analysis Email: >>> [email protected] >>> STFC Rutherford Appleton Laboratory >>> R25, 2.22 >>> Harwell Campus, Didcot, OX11 0QX, U.K. >>> >>> >>> From: Pamment, Alison (STFC,RAL,RALSP) >>> Sent: 03 February 2016 15:32 >>> To: Juckes, Martin (STFC,RAL,RALSP); [email protected] >>> Subject: RE: Confusing skin temperature and interface temperature >>> >>> Dear Martin, >>> >>> Thank you for pointing this out. I agree that since the introduction of the >>> very precisely defined sea_surface_skin_temperature name, the definition of >>> the more generic name is confusing. I agree with your suggested amendment >>> and unless anyone objects within the next seven days the change will be >>> accepted and added at the next update of the standard name table. >>> >>> Best wishes, >>> Alison >>> >>> From: Juckes, Martin (STFC,RAL,RALSP) >>> Sent: 02 February 2016 16:07 >>> To: [email protected]; Pamment, Alison (STFC,RAL,RALSP) >>> Subject: Confusing skin temperature and interface temperature >>> >>> Hello All, >>> >>> The CF Standard Name sea_surface_temperature includes the statement that it >>> is ".... not the skin temperature, whose standard name is >>> surface_temperature". The last phrase here is incorrect: the standard name >>> of the skin temperature is sea_surface_skin_temperature, not >>> surface_temperature. Can the definition be modified to read ".. not the >>> skin or interface temperature, whose standard names are >>> sea_surface_skin_temperature and surface_temperature respectively"? >>> >>> regards, >>> Martin >>> >>> >>> >>> >>> >>> _______________________________________________ >>> CF-metadata mailing list >>> [email protected] >>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >>> >>> _______________________________________________ >>> CF-metadata mailing list >>> [email protected] >>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >>> This message and any attachments are intended for the use of the addressee >>> or addressees only. >>> The unauthorised disclosure, use, dissemination or copying (either in whole >>> or in part) of its >>> content is not permitted. >>> If you received this message in error, please notify the sender and delete >>> it from your system. >>> Emails can be altered and their integrity cannot be guaranteed by the >>> sender. >>> >>> Please consider the environment before printing this email. >> > > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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