[CF-metadata] New Standard Names for Satellite Data

From: Aleksandar Jelenak - NOAA Affiliate <aleksandar.jelenak>
Date: Tue, 30 Apr 2013 21:11:07 -0400

Dear Jonathan,

Thank you for reviewing those unattended standard name proposals.

On Sun, Apr 21, 2013 at 4:18 PM, Jonathan Gregory
<j.m.gregory at reading.ac.uk> wrote:
> A sensor is not necessarily a device which measures radiation. In fact the
> only existing standard name containing this word is
> temperature_of_sensor_for_oxygen_in_sea_water. Hence, it might be helpful to
> add some other word(s) to sensor_band to make it explicit that it is referring
> to measurement of radiation. That word is already used in the standard_names
> radiation_frequency and radiation_wavelength.

I thought combining "sensor", "band", and one of the spectral terms
would provide enough clues. I don't think there are better
alternatives but if the names must change then how about one of these
forms:

emr_sensor_band_central_*

sensor_band_central_emr_*

sensor_band_central_radiation_*

"emr" stands for "electromagnetic radiation" since there is also
particle radiation.

> The word "central" does not obviously mean "first moment" to me. There are
> existing standard_names with moments mentioned e.g.
> sea_surface_wave_mean_period_from_variance_spectral_density_first_frequency_moment
> Is this analogous to your use?

"central" has to be in the names as that is how those values are
called in remote sensing. Anything otherwise would make them
unrecognizable to those who are supposed to be using them the most.

> Are the "central" wavelength, wavenumber and frequency all equivalent, or are they separate convolutions with the spectral
> response function?

They are separate convolutions.

> bounds could also be used to indicate the extent of the band.

The band interval is not so important information. And in the context
of the bounds CF attribute that was mentioned in several recent
threads, band intervals can overlap and I think that would invalidate
the use of this attribute.

> Why is senor_zenith_angle distinct from the existing platform_zenith_angle? Can
> you see the sensor separately from the platform (satellite)?

The two names allow better description of the reference used to
calculate those zenith angles. For some viewing geometries the sensor
and the platform cannot be assumed close enough to neglect that
difference.

> When I look up "look angle" in Google, its main meaning appears to be the
> elevation angle for seeing a satellite, rather than the angle of observation
> from a satellite. I wonder if there is alternative phrase that could be used
> for this.

 It is different in remote sensing, I guess it depends on the vantage
point. :-) "view" can be an alternative to "look" but don't think it
really changes much:

platform_view_angle
sensor_view_angle

My initial proposal used "scan" but a member of the cf-satellite
community requested a change since some sensors do not scan.

> Also, what does the line of sight of the platform mean (as distinct from the line of sight of the sensor)?

The intention is the same as explained above for the platform and
sensor zenith angles.

> The opposite of zenith is nadir. Could that word be used to describe the angle wrt straight down?

I deliberately did not want to use the term nadir to avoid the debate
over whether it is geocentric or geodetic nadir. The definition is
purposefully vague in that regard.

> What is the use case for the relative angles? It might be helpful to be more specific if possible.

To describe the difference in viewing geometries from two different
sensors over the same target. I think the definitions are specific
enough.

> However, I do have a comment on toa_brightness_temperature_bias_at_standard_scene_wrt_intercalibration. I wonder if this could be simpler e.g.
> bias_in_toa_brightness_temperature_of_standard_scene. That also has the advantage of being the same as the previous one with a bit added.

The reason for that bias is intercalibration so it should probably be
in the name. Did you mean:

bias_in_toa_brightness_temperature_of_standard_scene_wrt_intercalibration ?

       -Aleksandar
Received on Tue Apr 30 2013 - 19:11:07 BST