Hi Philip-
Your statement is correct:
Philip said:
> as I understand it, antenna temperature is a similar type of quantity as brightness temperature. Am I correct? If so, antenna_temperature would seem the obvious choice for CF (following brightness_temperature which is already part of CF)
So, antenna_temperature is not the temperature of the antenna, but is
part of the process of measuring microwave radiation from space. The
antenna reflects radiation from the Earth to the feedhorn. So the
antenna_temperature is the radiation measured at the feedhorn prior to
correction for other effects. The following link might clear this up for
those interested (not brief, but helpful).
http://brucegary.net/MTP_tutorial/MTP_ch3.html
-Ken Knapp
On 5/2/2011 10:13 PM, Cameron-smith, Philip wrote:
> Hi John,
>
> I think this was an issue worth raising. There certainly seems to be the potential for ambiguity.
>
> I just searched the CF archive to find any approved examples of either physical_quantity_by_instrument or physical_state_of_instrument.
>
> I had thought there were cases of the former for specific satellite instruments, but I couldn't find one. Perhaps I missed it, or it was discussed but not approved yet.
>
> I did find one example of the latter:
>
> temperature_of_sensor_for_oxygen_in_sea_water
>
> If we followed this convention, then the temperature of the antenna (if it were required) would presumably be something
> like:
>
> temperature_of_antenna,
>
> I am not an expert in antennas, but as I understand it, antenna temperature is a similar type of quantity as brightness temperature. Am I correct? If so, antenna_temperature would seem the obvious choice for CF (following brightness_temperature which is already part of CF), and it would avoid ambiguity because of the example above.
>
> Best wishes,
>
> Philip
>
> -----------------------------------------------------------------------
> Dr Philip Cameron-Smith, pjc at llnl.gov, Lawrence Livermore National Lab.
> -----------------------------------------------------------------------
>
>
>> -----Original Message-----
>> From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-
>> bounces at cgd.ucar.edu] On Behalf Of John Graybeal
>> Sent: Monday, May 02, 2011 2:34 PM
>> To: Ken Roberts
>> Cc: cf-metadata at cgd.ucar.edu
>> Subject: Re: [CF-metadata] New CF Standard Name (antenna_temperature)
>>
>> You're right, I can't argue that 'antenna temperature' is widely used
>> in another way. Though by limiting your field to remote sensing, you
>> are excluding some heavy in situ users of CF, the ocean communities.
>>
>> In ocean systems I've seen many a 'component_temperature' pattern, from
>> can_temperature to processor_temperature to panel_temperature (none in
>> CF, mind you -- it's not a concept that is easily interoperable). I
>> can't swear from personal experience I've ever seen an
>> antenna_temperature; maybe no one *ever* cares about that.
>>
>> So I'll only toss out there that 'antenna noise temperature' has no
>> possible ambiguity with antenna physical temperature, and seems to be
>> the Wikipedia term of choice (even if 'antenna temperature' wins the
>> Google fight by about 5 to 1 :->) -- just in case you like 'antenna
>> noise temperature' equally well. Of course, Wikipedia defines that as
>> "the temperature of a hypothetical resistor at the input of an ideal
>> noise-free receiver that would generate the same output noise power per
>> unit bandwidth as that at the antenna output at a specified frequency"
>> -- it may be that you have in mind a different concept.
>>
>> I will stop rambling now on this topic, so if no one else expresses
>> concern you may consider me agreeable.
>>
>> john
>>
>> On May 2, 2011, at 06:11, Ken Roberts wrote:
>>
>>> John,
>>>
>>> We could not find any well-cited or commonly known circumstances in a
>>> related field (to remote sensing) where the antenna temperature can
>> mean
>>> "the temperature of the antenna itself." Maybe you could suggest a
>> case
>>> where antenna temperature has such a meaning in terms of measurements
>> so
>>> we can identify a potential conflict. As far as we can tell, antenna
>>> temperature is used to "relate the power emitted by [a] source to an
>>> interesting physical property of that source."
>>> [http://map.gsfc.nasa.gov/site/glossary.html]
>>>
>>> Regards,
>>> Ken
>>>
>>> On 4/27/2011 12:30 PM, John Graybeal wrote:
>>>> Sorry, a doofus question here.
>>>>
>>>> Isn't the antenna temperature affected to some degree by the
>> temperature of the environment it is in? I am thinking of temperature
>> in the common vernacular, sorry if that is the wrong context. But I
>> see a potential conflict with those measurements of antenna temperature
>> that are taken strictly to learn what the temperature of the antenna
>> is, and having nothing to do with the power per unit bandwidth received
>> from a source.
>>>> John
>>>>
>>>> On Apr 27, 2011, at 08:51, Ken Roberts wrote:
>>>>
>>>>> All,
>>>>>
>>>>> If there are no objections or requested changes, can it be
>> confirmed
>>>>> that the following proposed name will be added to the next version
>> of
>>>>> the CF Standard Name Table?
>>>>>
>>>>> Standard Name: antenna_temperature
>>>>> Definition: A measure of the power per unit bandwidth received from
>> a
>>>>> source by an antenna
>>>>> Units: Kelvin
>>>>>
>>>>> Thanks,
>>>>> Ken
>>>>>
>>>>> On 4/6/2011 12:48 PM, Ken Roberts wrote:
>>>>>> All,
>>>>>>
>>>>>> The National Climatic Data Center (NCDC) has a Special Sensor
>>>>>> Microwave/Imager (SSM/I) product currently being developed for the
>>>>>> Climate Data Record (CDR) program. The dataset contains variables
>> for
>>>>>> brightness temperature and corresponding antenna temperature
>> values.
>>>>>> Given that there does not appear to be a fitting CF standard name
>> for
>>>>>> antenna temperature, we would like to propose a new name,
>>>>>> antenna_temperature, defined as a measure of the power per unit
>>>>>> bandwidth received from a source by an antenna (units are Kelvin).
>>>>>>
>>>>>> Regards,
>>>>>> Ken
>>>>>>
>>>>> --
>>>>> Ken P. Roberts
>>>>> Programmer Analyst, STG, Inc., Government Contractor
>>>>> Remote Sensing& Applications Division
>>>>> National Climatic Data Center
>>>>> 151 Patton Ave.
>>>>> Asheville, NC 28801-5001
>>>>> Phone: (828) 271-4083
>>>>> Fax: (828) 271-4328
>>>>> Ken.Roberts at noaa.gov
>>>>>
>>>>> _______________________________________________
>>>>> CF-metadata mailing list
>>>>> CF-metadata at cgd.ucar.edu
>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>>>
>>>> John Graybeal<mailto:jgraybeal at ucsd.edu>
>>>> phone: 858-534-2162
>>>> Product Manager
>>>> Ocean Observatories Initiative Cyberinfrastructure Project:
>> http://ci.oceanobservatories.org
>>>> Marine Metadata Interoperability Project: http://marinemetadata.org
>>>>
>>>
>>> --
>>> Ken P. Roberts
>>> Programmer Analyst, STG, Inc., Government Contractor
>>> Remote Sensing& Applications Division
>>> National Climatic Data Center
>>> 151 Patton Ave.
>>> Asheville, NC 28801-5001
>>> Phone: (828) 271-4083
>>> Fax: (828) 271-4328
>>> Ken.Roberts at noaa.gov
>>>
>>> _______________________________________________
>>> CF-metadata mailing list
>>> CF-metadata at cgd.ucar.edu
>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>
>>
>> John Graybeal<mailto:jgraybeal at ucsd.edu>
>> phone: 858-534-2162
>> Product Manager
>> Ocean Observatories Initiative Cyberinfrastructure Project:
>> http://ci.oceanobservatories.org
>> Marine Metadata Interoperability Project: http://marinemetadata.org
>>
>> _______________________________________________
>> CF-metadata mailing list
>> CF-metadata at cgd.ucar.edu
>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> _______________________________________________
> CF-metadata mailing list
> CF-metadata at cgd.ucar.edu
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
--
Ken Knapp
Remote Sensing and Applications Division
National Climatic Data Center
151 Patton Ave
Asheville, NC 28801
828-271-4339 (voice) 828-271-4328 (fax)
IBTrACS: http://www.ncdc.noaa.gov/oa/ibtracs/
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"Worry is the interest paid by those who borrow trouble."
-George Washington
Received on Tue May 03 2011 - 06:09:40 BST
