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, [email protected], Lawrence Livermore National Lab.
-----------------------------------------------------------------------
-----Original Message-----
From: [email protected] [mailto:cf-metadata-
[email protected]] On Behalf Of John Graybeal
Sent: Monday, May 02, 2011 2:34 PM
To: Ken Roberts
Cc: [email protected]
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
[email protected]
_______________________________________________
CF-metadata mailing list
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John Graybeal<mailto:[email protected]>
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
[email protected]
_______________________________________________
CF-metadata mailing list
[email protected]
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
John Graybeal<mailto:[email protected]>
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
[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
--
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/
GridSat: http://www.ncdc.noaa.gov/oa/gridsat/
HURSAT: http://www.ncdc.noaa.gov/oa/rsad/hursat/
"Worry is the interest paid by those who borrow trouble."
-George Washington
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