John, I think we (I, anyway) were waiting for a little more clarification as to
what was needed. Sorry for that delay. I like the name itself, makes sense to
me.
Unless I am mistaken, from your email I infer that the meaning of this is a
narrow case of surface_backwards_scattering_coefficient_of_radar_wave. That
description is:
> The scattering/absorption/attenuation coefficient is assumed to be an
> integral over all wavelengths, unless a coordinate of radiation_wavelength is
> included to specify the wavelength. Scattering of radiation is its deflection
> from its incident path without loss of energy. Backwards scattering refers to
> the sum of scattering into all backward angles i.e. scattering_angle
> exceeding pi/2 radians. Ascattering_angle should not be specified with this
> quantity.
I can't tell from the description if this item is different, so the description
could use a little bit more meat to tease that out. Looking at your thread, I
see this:
> we are calculating sigma_naught which is the fraction of incident power that
> is reflected by the surface. It is also very important in scatterometry to
> record the angle of incidence as the sigma_naught changes based on the
> incidence angle in addition to various other parameters which are essential
> to being able to correlate data from various scatterometers.
So does it work for the description could say something like the following?
This is still similar to the other standard name, so if there are specific
things that make the distinction clear that would be important to add. ("This
differs from surface_backwards_...")
> The fraction of incident power that is reflected by the surface. (In
> microwave remote sensing this is also known as the 'normalized radar cross
> section' or 'sigma naught', when produced from one angle of incidence and
> from one wavelength.) Scattering of radiation is its deflection from its
> incident path without loss of energy. Backwards scattering refers to the sum
> of scattering into all backward angles i.e. scattering_angle exceeding pi/2
> radians. A scattering_angle should not be specified with this quantity.
> Coordinates of radiation_wavelength and angle_of_incidence are used to
> specify those baseline parameters.
I'm not sure about the last part -- if they are always needed these variables
should be required.
John
On Jul 22, 2014, at 14:49, Niedfeldt, John C (398M-Affiliate)
<[email protected]> wrote:
> Dear all,
> Hello again! About two months back I sent in a request, which is referenced
> below, in which I requested that we add the
> ‘normalized_radar_backscatter_coefficient’ in CF. Having heard nothing to the
> contrary, and seeing as no other standards name match our needs, we at
> PO.DAAC will be moving forward in implementing this new standard name.
>
> As our newly reprocessed netCDF datasets shall soon serve as an online
> replacement for existing datasets already in use by hundreds of
> interdisciplinary scatterometry data users, we hope to likewise hear back
> from you soon as to whether there is consensus on our proposed standard name.
> If there is anything further we can do to build community consensus on our
> proposed standard name, please let me know.
>
> Sincerely,
> John
>
> --
> John Niedfeldt
> Data Engineering
> PO.DAAC, JPL
>
> From: Lauret Olivier <[email protected]>
> Date: Friday, May 30, 2014 at 8:11 AM
> To: "[email protected]" <[email protected]>
> Cc: JPL <[email protected]>
> Subject: TR: normalized_radar_backscatter_coefficient
>
> Hi all,
>
> Just forwarding you some discussion we have with J. Niedfeldt about some
> standard name for sigma naught variable. I thought the available
> “surface_backwards_scattering_coefficient_of_radar_wave” could be used
> considering some changes in the definition [in short I wish we could mix the
> description of sigma naught from radar altimetry with the one from
> scatterometers]. But it seems that the quantities are different enough to
> introduce a new standard name (see the message below).
>
> Can we introduce ‘normalized_radar_backscatter_coefficient’ in CF?
>
> Thanks,
>
> Olivier
>
> De : Niedfeldt, John C (398M-Affiliate)
> [mailto:[email protected]]
> Envoyé : jeudi 29 mai 2014 21:26
> À : Lauret Olivier
> Objet : normalized_radar_backscatter_coefficient
>
> Dear Mr. Olivier,
> After discussion with Dr. David Long of BYU and reviewing the current
> definition with him it was determined that we do in fact need a new variable.
> In microwave remote sensing the normalized radar cross section, sigma naught,
> is always produced from one angle of incidence and from one wavelength. I
> understand the desire to consolidate the number of standard names and to not
> have duplication, but adding this standard name would reduce confusion and
> error for many I believe. It is also general enough that we can add
> attributes to it in the future to allow further specification for various
> endeavors. If you have any more questions feel free to contact me and thank
> you again for your assistance. We changed the standard_name to be more
> descriptive.
>
> standard_name:
> normalized_radar_backscatter_coefficient
>
> Definition:
> normalized_radar_backscatter_coefficient is also called the normalized radar
> cross section, which are commonly used in the microwave remote sensing
> community.
>
> Canonical Units:
> 1
>
>
> Sincerely,
> John Niedfeldt
>
>
> Cliquez ici si ce message est indésirable (pourriel).
>
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