Dear All,

I'd just like to reinforce John's last point that the semantics of 'instrument' 
and 'platform' are becoming blurred in these discussions.  From my perspective 
as one who has to map to CF datasets I would prefer it if the semantics of 
terms used in Standard Names had a universally understood meaning.

Another point that struck me from John's response is that when we do have 
multiple data streams sharing a single Standard Name, we need to ensure that 
there are objective criteria (i.e. not plaintext in the longname) that enable 
each stream to be uniquely identified.  Otherwise, even 'common concepts' 
(which incidentally will be worked during a workshop in November) won't deliver 
interoperability.

Cheers, Roy.

-----Original Message-----
From: cf-metadata-boun...@cgd.ucar.edu 
[mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Aleksandar Jelenak
Sent: 20 October 2010 01:33
To: cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] New standard names for satellite obs data

Dear Evan,

Thanks for your suggestions.

Evan Manning wrote on 10/18/10 11:30 PM:
> The names below mix "satellite" and "instrument" differently than I'm
> used to.

I started with "satellite_*" names but then wanted to generalize since 
remote sensing instruments are not only carried on satellites. But you 
brought up an important distinction that the observation geometry of an 
instrument can be different from the generic one associated with the 
entire spacecraft.

> I recommend changing:
>    instrument_zenith_angle ->  satellite_zenith_angle
>    instrument_azimuth_angle ->  satellite_azimuth_angle
>    satellite_scan_angle ->  satellite_view_angle

I think the "instrument_*" names are more applicable as they allow for 
either instrument-specific or spacecraft-generic geometries. I also 
think being able to distinguish between the two observation geometries 
is important and would like to have sets of standard names for both. So 
a data provider can clearly signal what is given, even for data from the 
same instrument.

To summarize:

1) Use "instrument_zenith_angle", "instrument_azimuth_angle", and 
"instrument_scan_angle" for precise, instrument-specific observation 
geometry.

2) Use "platform_zenith_angle", "platform_azimuth_angle", and 
"platform_view_angle" for generic satellite (here generalized to 
"platform") observation geometry.

3) Mixing names from these two sets is allowed, whatever is more 
applicable for the zenith, azimuth, and scan/view angle data.

Too complicated?

> And add:
>    instrument_scan_angle
>      The angle between the line of sight from an instrument and its
>      reference scan position.

Agree.

        -Aleksandar
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