Re: [cf-satellite] New Standard Names for Satellite Data

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Greetings all,
A few of us here at RSS took a look at your new names and offer some thoughts:
1. For the platform and sensor look angle as written, nadir is defined 
as pointing towards the center of the Earth.  We question whether this 
is appropriate for all cases, as many satellites are flown with nadir 
pointing toward the closest place on Earth, so that the nadir look has 
an incidence angle of 0.   (geodetic vs. geocentric pointing).  We 
suggest separate geodetic and geocentric look angle definitions to 
reduce confusion, such as sensor_look_angle_geocentric and 
sensor_look_angle_geodetic.
2.  There is only a 
linear_term_of_spectral_radiance_correction_due_to_intercalibration and 
a constant_term_of_spectral_radiance_correction_due_to_intercalibration. 
Many microwave radiometers have quadratic (or higher order) terms in the 
calibration and subsequent calibration corrections.  We suggest adding 
more names.
3.  Azimuth angle definitions need to be clearer (see suggested changes 
in bold below).   We would like to be sure that the definition is 
unambiguous.  For example, the definition of platform_azimuth_angle 
would be clearer if it read:
"platform" refers to the vehicle from which observations are made e.g. 
airplane, ship, or satellite. Platform azimuth angle is the horizontal 
angle between the line of sight *from the observation point *to the 
platform and a reference direction *at the observation point,* which is 
often due north. The angle is measured clockwise*starting from the 
reference direction*.
4.  The definition for sensor_band_central_wavenumber does not say 
whether  the first moment of the band's normalized spectral response 
function is averaged over wavelength or frequency.  One can't invert 
wavelength and wavenumber if not calculated correctly.
Thanks for taking these points into consideration.   Significant input 
came from Carl Mears and Kyle Hilburn at RSS.
-Deborah



--
Deborah K Smith
Scientist
Remote Sensing Systems
smith@xxxxxxxxx
www.remss.com
www.discover-earth.org

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