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[CF-metadata] 4. Re: New Standard Names for Satellite Data

From: Schultz, Martin <m.schultz>
Date: Wed, 17 Apr 2013 06:36:56 +0000

Dear Aleksandar,

     nice job! Putting your proposal on http://wiki.esipfed.org/index.php/Standard_Names_For_Satellite_Observations#Proposal_.232 like this makes it easily tractable.

Sorry if I may be a little late, but upon reading through I have some minor concerns about:

"relative_platform_azimuth_angle" and "relative_platform_azimuth_angle": in my understanding "relative" denotes a (percent) fraction rather than a difference. Therefore, I think this term could be misleading. Wouldn't "platform_azimuth_angle_difference" be more precise?

Out of curiosity: isn't there a need to describe several other platform/sensor/solar/viewing angles? It might help to refer to some figure (e.g. on a web site) which illustrates the various geometrical aspects needed. For example, I am wondering if "sensor zenith angle" and "sensor look angle" aren't the same, only shifted by 180 degrees. It might still be ok to have two different standard names for them (because they are different quantities), but in this case a sentence should be added to the definition such as "Note that zenith_angle and look_angle are related by zenith_angle = (look_angle + 180) mod 360".

And, please excuse my ignorance, but "covariance_between_constant_and_linear_terms_of_radiance_per_unit_wavenumber_correction_due_to_intercalibration" does sound rather specific and incomprehensible to me, even if I read through the definitions of constant_term_of_radiance_per_unit_wavenumber_correction_due_to_intercalibration and linear_term_of_radiance_per_unit_wavenumber_correction_due_to_intercalibration. Is this a general concept, or are these variables needed for one specific satellite sensor? Do we run the "danger" to see many more such proposals with other (inter)calibration concepts? I think, these definitions require a far more extensive description (i.e. definition), again, for example pointing to a web reference where the sensor concept and/or viewing geometry is described. It may thus be better from the standard_name perspective to try and find a somewhat more generalized term (if this is indeed sensor specific) and require/request a comment attribute which would then detail the exact procedure
used. As an extreme (and perhaps unrealistic) suggestion, one could think about "covariance_between_correction_terms_due_to_intercalibration". The comment attribute would then have to specify that these are corrections of "radiance_per_unit_wavenumber", and that the covariance refers to "constant and linear terms".

Best regards,

Martin



PD Dr. Martin G. Schultz
IEK-8, Forschungszentrum J?lich
D-52425 J?lich
Ph: +49 2461 61 2831




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Received on Wed Apr 17 2013 - 00:36:56 BST

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