Dear Jonathan Gregory,
A few days ago, I submitted a proposal for a new standard name,
land_surface_skin_temperature. This name would essentially be the land
analogue for the "sea_surface_skin_temperature" standard name. However,
through some of the dialogue on the CF mailing list re: this submission,
a few related questions have arose:
1) What is meaning of the "surface_temperature" standard name? The
definition states that it is the temperature of the interface, and not
the medium above or below. What does this mean? There has be some
medium to have a temperature.
2) The "sea_surface_temperature" definition seems to incorrectly refer
to the "surface_temperature", when it should refer instead to the
"sea_surface_skin_temperature." But, I can't say this for sure in light
of question #1.
3) Karl Taylor has raised the question that if someone searches for
surface temperature, this is the same as the skin temperature. So,
there could be some ambiguity between the surface temperature and
surface skin temperature names in CF, which may or may not be intended.
4) After question #1-3 are determined, this should presumably make it
easier to determine the role of the proposed
"land_surface_skin_temperature" name.
Sorry to put so many questions in one post, but it seemed like my latest
post generated several questions, and I thought putting them all in one
place might make things a little less confusing. Thanks in advance for
your feedback.
Sincerely,
Jonathan Wrotny
On 6/10/2013 12:54 PM, Jonathan Wrotny wrote:
> Jim,
>
> This is a good question and you raise a good point. I have to admit
> that I too am a little confused by the definition of "surface
> temperature" in the CF database. My initial interpretation was that
> this quantity refers to the temperature at the lowest level of the
> atmosphere, i.e. just above the surface, so that it is actually an air
> temperature. But, how can the "surface temperature" be an air
> temperature (or a skin temperature, for that matter) if it is "not the
> bulk temperature of the medium above or below (the interface)"?
>
> Could someone help please clarify the "surface temperature" quantity?
>
> Jonathan Wrotny
>
> On 6/10/2013 12:30 PM, Jim Biard wrote:
>> I'd appreciate it if someone would take the time to help an ignorant
>> soul understand how a non-physical boundary such as the interface
>> between the land surface and the atmosphere can have a temperature.
>> It sure seems to me that you need some material in order to have a
>> temperature, and such an interface seems to have none.
>>
>> Jim Biard
>> Research Scholar
>> Cooperative Institute for Climate and Satellites <http://www.cicsnc.org/>
>> Remote Sensing and Applications Division
>> National Climatic Data Center <http://www.ncdc.noaa.gov/>
>> 151 Patton Ave, Asheville, NC 28801-5001
>>
>> jim.biard at noaa.gov <mailto:jim.biard at noaa.gov>
>> 828-271-4900
>>
>>
>>
>> Follow us onFacebook <https://www.facebook.com/cicsnc>!
>>
>> On Jun 10, 2013, at 11:52 AM, Jonathan Wrotny <jwrotny at aer.com
>> <mailto:jwrotny at aer.com>> wrote:
>>
>>> Dear Jonathan Gregory,
>>>
>>> I have not yet replied to this e-mail yet from you...thanks for the
>>> information on the meaning of the various surface temperatures.
>>>
>>> Yes, the land skin temperature is actually different from the
>>> "surface_temperature" standard name since it corresponds to the
>>> skin, and not the interface, temperature. So, I do believe that an
>>> additional name will need to be added to account for this land
>>> analogue to "sea_surface_skin_temperature." Here is my current
>>> proposal:
>>>
>>> Standard Name: land_surface_skin_temperature
>>>
>>> Definition:The surface called "surface" means the lower boundary of
>>> the atmosphere. The land surface skin temperature is the temperature
>>> measured by an infrared radiometer, but measurements from microwave
>>> radiometers operating at GHz wavelengths also exist. It represents
>>> the aggregate temperature of the skin surface where "skin" means the
>>> surface medium viewed by a sensor to a vertical depth of
>>> approximately 12 micrometers.
>>>
>>> Measurements of this quantity are subject to a large potential
>>> diurnal cycle which is primarily due to the balance between heating
>>> during the day by solar radiation and continual cooling from
>>> terrestrial (long-wave) radiation emitted by the skin surface.
>>>
>>> Canonical Units:K
>>>
>>>
>>> Sincerely,
>>>
>>> Jonathan
>>>
>>> On 6/7/2013 3:47 AM, Jonathan Gregory wrote:
>>>> Dear Jonathan W
>>>>
>>>>> If my interpretation of all of the surface temperature names is
>>>>> correct, then there may need to be a modification to the current
>>>>> definition of "sea_surface_temperature." In particular, this
>>>>> definition states "It is the temperature of sea water near the
>>>>> surface (including the part under sea-ice, if any), and not the skin
>>>>> temperature, whose standard name is surface_temperature." However,
>>>>> it seems to me that the "surface_temperature" is the
>>>>> atmosphere/medium interface temperature, and not the temperature of
>>>>> the medium below the interface (e.g. the skin temperature). So, I'm
>>>>> wondering if the above sentence in quotes incorrectly refers to the
>>>>> "surface_temperature" when perhaps it should refer to the
>>>>> "sea_surface_skin_temperature"?
>>>> Yes, I think you are right. This definition of sea_surface_temperature may
>>>> predate the introduction of sea_surface_skin_temperature. The SST is neither
>>>> the true interface temperature (for which the name is surface_temperature) nor
>>>> the "skin" temperature, but a bulk temperature applying to a rather ill-defined
>>>> upper layer of the ocean. There isn't a land analogue for SST.
>>>>
>>>> If land skin temperature is different from surface_temperature of the
>>>> interface, a new name is needed for it, I agree.
>>>>
>>>> Cheers
>>>>
>>>> Jonathan
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>>>
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>
>
>
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Received on Thu Jun 13 2013 - 11:04:26 BST
