> Sometimes these instruments are also flown on aircraft, so do we want to
> hardwire 'satellite' into the standard_name? It is a bit of a mouthful, but
> would 'remote_sensing_instrument_' work?
According to the definition, there is nothing related to the satellite in
instrument_scan_angle: "The angle between the line of sight from an instrument
and its reference scan position." We don't know whether the reference scan
position is defined relative to the host platform, to the earth, to the sky, or
to the instrument's frame. It would only be appropriate to add a platform
reference if the relationship to it is clear in the context of the definition.
More generally, there is another concern, with the definition of line of sight.
If the 'instrument_x_angle is changed to satellite_x_angle or platform_x_angle
(or 'y_x_angle' :->), the question becomes, how is the line of sight of the
satellite (platform, y) defined? Some satellites/platforms have multiple
instruments with different lines of sight, so it is not always obvious. A
recommendation here is to define the line of sight in CF as the "primary
viewing direction, or a defined primary reference axis for the system", and
expect that to be defined for the hardware item in question in the description
of the variable.
More generally still, from OGC Sensor Web Enablement (and other) work, it is
apparent there can be multiple instances nested within each other -- a sensor
within an instrument within another instrument within a platform, to pick an
example. A more systematic approach references all of these with a single term
('system' is used in SWE, and works reasonably well). Alas, if you want all of
those in one data set, you will have multiple variables with the same
standard_name. But that will also be true if sensor, instrument, platform are
the 3 prefixes (since at least two of those concepts nest).
But (hopefully I recall this correctly) there is nothing that says a
standard_name can only be used once in a data set, so from that perspective I
would propose 'system' as the noun, backfilled by 'sensor', 'instrument', or
'platform' if particular communities need/want that.
Bear in mind that, to the extent we want CF to represent data that is readily
interoperable, the use of any of these standard names will not promise
interoperability for the corresponding data, since my sensor may be your
instrument, and someone else's platform, just by virtue of our own already
divergent use of those terms. But they are quite useful in context, so I hope
we still get to use them.
john
On Oct 19, 2010, at 16:44, Cameron-smith, Philip wrote:
> Hi Jonathan,
>
> Sometimes these instruments are also flown on aircraft, so do we want to
> hardwire 'satellite' into the standard_name?
>
> It is a bit of a mouthful, but would 'remote_sensing_instrument_' work?
>
> Best wishes,
>
> Philip
>
> -----------------------------------------------------------------------
> Dr Philip Cameron-Smith, p...@llnl.gov, Lawrence Livermore National Lab.
> -----------------------------------------------------------------------
>
>
>
>> -----Original Message-----
>> From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-
>> boun...@cgd.ucar.edu] On Behalf Of Jonathan Gregory
>> Sent: Tuesday, October 19, 2010 6:40 AM
>> To: cf-metadata@cgd.ucar.edu
>> Subject: Re: [CF-metadata] New standard names for satellite obs data
>>
>> Dear Evan et al.
>>
>> I agree with this:
>>> instrument_zenith_angle -> satellite_zenith_angle
>>> instrument_azimuth_angle -> satellite_azimuth_angle
>>> satellite_scan_angle -> satellite_view_angle
>>
>>> And add:
>>> instrument_scan_angle
>>> The angle between the line of sight from an instrument and its
>>> reference scan position.
>>
>> Could you put "satellite" in there too as well somehow? "Instrument" is
>> a very
>> general word and it may not obvious what the phrase refers to without
>> mentioning "satellite".
>>
>> Cheers
>>
>> Jonathan
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> _______________________________________________
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John Graybeal <mailto:jgrayb...@ucsd.edu>
phone: 858-534-2162
System Development Manager
Ocean Observatories Initiative Cyberinfrastructure Project:
http://ci.oceanobservatories.org
Marine Metadata Interoperability Project: http://marinemetadata.org
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