Dear Martin, Thanks for taking the time to review the proposed names.
On Wed, Apr 17, 2013 at 2:36 AM, Schultz, Martin <[email protected]> wrote: > "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? The term "relative" is also used to describe difference, for example "relative velocity" is a difference between two velocity vectors. Using "relative" also keeps those names more familiar to the satellite data community. > Out of curiosity: isn't there a need to describe several other > platform/sensor/solar/viewing angles? Several such angles are already in the official table. My proposal complements that and I have initially used the definitions from those names as templates. > I am wondering if "sensor zenith angle" and "sensor look angle" aren't the > same, only shifted by 180 degrees. No, the relationship is not that simple because these angles are calculated approximating the Earth as an oblate spheroid. Below is a new definition for sensor_zenith_angle that is hopefully more graphical and less confusing: Standard name: sensor_zenith_angle Definition: The angle between the line of sight to the sensor and the local zenith at the observation target; a value of zero is directly overhead the observation target. Local zenith is a line perpendicular to the Earth’s surface at a given location. Observation target is a location on the Earth defined by the sensor performing the observations. > 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 I agree this standard name is unusual. > Is this a general concept, or are these variables needed for one specific > satellite sensor? It is a general concept for one way of expressing the uncertainty of satellite sensor inter-calibration. The CF convention does not currently have a similar concept and the NetCDF-U convention does not seem to have matured enough for use. > Do we run the "danger" to see many more such proposals with other > (inter)calibration concepts? I don't see the "danger"; look how many standard names for atmospheric chemical compounds are in the table now. > 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". The approach you outline appears to me as similar to what the NetCDF-U convention tries to achieve. If this standard name is deemed too unusual I am fine to drop it from the proposal. -Aleksandar _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
