Confirming what Jonathan says, sea_surface_temperature was was used to describe data (including observations going many decades back) that reflected a variety of locations -- right at the interface (with remote sensors), or varying distances under the skin (with in situ sensors, including buckets dipped in the water and measured on the ship). The existing body of data using that concept made it broad beyond utility.
The somewhat sloppy vertical range definitions were influenced by measurement technologies and the physics underlying them.
The recommended practice, at the conclusion of the process adding the 3 new variables, was that no new data should use the term sea_surface_temperature, because it was too meaningless. (Not sure if that got captured anywhere in the definitions.) All new data should use one of the 3 new concepts (skin, subskin, foundation), according to the precise meaning. There was discussion of deprecating the original term, but people felt it was necessary at times, e.g. for older data sets with unknown measurement characteristics.
John
On Jun 20, 2013, at 09:24, Jonathan Gregory <j.m.gregory at reading.ac.uk> wrote:
> Dear Karl
>
> As I wrote in a previous posting, I think surface_temperature is either a some-
> what vague concept, to be used when it is not critical to say exactly what is
> meant (that's fine - standard names have always supported a range of precision
> in concepts), or it's an idealisation which really refers to an energy balance
> at the interface. The latter concept is applicable in models, and then does
> not necessarily have any matter associated with it.
>
> Best wishes
>
> Jonathan
>
> ----- Forwarded message from Karl Taylor <taylor13 at llnl.gov> -----
>
>> Date: Thu, 20 Jun 2013 09:15:36 -0700
>> From: Karl Taylor <taylor13 at llnl.gov>
>> User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:16.0)
>> Gecko/20121026 Thunderbird/16.0.2
>> To: cf-metadata at cgd.ucar.edu
>> Subject: Re: [CF-metadata] new standard name: land_surface_skin_temperature
>>
>> Dear all,
>>
>> O.K. I withdraw my suggestion to deprecate sea_surface_skin_temperature.
>>
>> I do think the definitions should say how skin temperature differs
>> from surface temperature. Maybe someone can explain that in a few
>> words.
>>
>> As I understand it, temperature is only defined when molecules are
>> involved. So surface_temperature I think should be defined as the
>> temperature of the surface molecules on the ocean or land/vegetated
>> surface. I don't think there are any useful observational
>> measurements of this temperature either in the ocean or land.
>> Models do calculate these a surface temperature, and as I understand
>> it models use this as their surface radiating temperature so in that
>> sense the temperature is identical to skin_temperature, I would
>> think.
>>
>> It sounds to me like in land observations, at least, the
>> skin_temperature is not precisely defined because the effective
>> radiating layer depends presumably on what wavelengths are being
>> sensed. To precisely say what the temperature represents one would
>> have to show what fraction of the radiation originated from
>> different depths. saying 10-20 microns of course gives an idea
>> about this, but it isn't precise.
>>
>> Also, the definition of land_surface_skin_temperature should clearly
>> indicate (when it represents an area mean) whether it is meant to be
>> the area mean of the soil or of the "solid or liquid surface" as
>> seen from above which might include vegetation, puddles, etc. [as
>> an aside, I wonder if the thickness of the layer producing the
>> radiation varies much from one material to the next.]
>>
>> It does seem a shame to me that users looking for
>> surface_temperature information will now have to search both for
>> surface_temperature and surface_skin_temperature, but I'll accede to
>> the clear majority that thinks both are necessary.
>>
>> best regards,
>> Karl
>>
>> On 6/20/13 4:56 AM, Jonathan Gregory wrote:
>>> Dear Karl
>>>
>>> Like Roy, I don't think we should deprecate sea_surface_skin_temperature.
>>> Although I cannot remember the arguments - which must be apparent in the
>>> mailing list archive - I do recall that it was a careful and long discussion
>>> with Craig which led to the introduction of the various SST names.
>>>
>>> Therefore adding land_surface_skin_temperature seems fine to me if there is
>>> a need to be precise about this as an observable quantity, which relates
>>> to a particular layer, even though it's very thin. The definition should note
>>> that if this precise meaning is not intended, the name surface_temperature
>>> could be used, which strictly refers to the temperature at the interface.
>>>
>>> Best wishes
>>>
>>> Jonathan
>>> _______________________________________________
>>> CF-metadata mailing list
>>> CF-metadata at cgd.ucar.edu
>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>
>
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>
>
> ----- End forwarded message -----
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------------------------------------
John Graybeal
Senior Data Manager, Metadata and Semantics
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Received on Thu Jun 20 2013 - 11:58:14 BST
