Hei Maarten,
the proposal looks generally good to me, but I would like to see toa
written out as top_of_atmosphere. In my world (atmospheric dispersion
modelling) toa is used for 'time of arrival' and the list of acronyms
for toa is even longer:
http://acronyms.thefreedictionary.com/TOA
Best regards,
Heiko
On 2014-11-12 18:32, Maarten Sneep wrote:
> Hi all,
>
> I hereby propose the addition of the following standard names. All are
> commonly used quantities used in passive satellite remote sensing, to be
> specific instruments that use ultra-violet, visible and near infra-red
> radiation for remote sensing of atmospheric composition, sometimes
> including wavelengths up to 2.5 micrometer (shortwave radiation).
>
> Examples of these instruments include GOME, SCIAMACHY, OMI, GOME-2,
> OMPS, and the upcoming TROPOMI on Sentinel 5 precursor, and instruments
> on Sentinel 4 and Sentinel 5 missions.
>
> Please note the notes at the end.
>
> -------------------------------------------------------------------------
> * toa_incoming_photon_solar_irradiance_per_unit_wavelength
>
> "toa" means top of atmosphere. "Photon solar irradiance" is the photon
> flux on a surface perpendicular to the incoming solar radiation. The
> direction is specified as "incoming". A photon flux is specified in
> terms of numbers of photons expressed in moles. The "per unit
> wavelength" indicates a spectrally resolved quantity. A coordinate
> variable for radiation wavelength should be given the standard name
> radiation_wavelength.
>
> Canonical unit: mol m-2 m-1 s-1
>
> -------------------------------------------------------------------------
> * toa_outgoing_photon_radiance_per_unit_wavelength
>
> "toa" means top of atmosphere. "Photon radiance" is the photon flux in a
> particular direction, per unit of solid angle. The direction is
> specified as "outgoing", i.e. radiation from below. A photon flux is
> specified in terms of numbers of photons expressed in moles. The "per
> unit wavelength" indicates a spectrally resolved quantity. A coordinate
> variable for radiation wavelength should be given the standard name
> radiation_wavelength.
>
> Canonical unit: mol m-2 m-1 s-1 sr-1
>
> -------------------------------------------------------------------------
> Note 1: The coordinate variable for radiation wavelength may require a
> mapping that is similar to the mapping of geolocation coordinates for
> satellite observations, i.e. not a dimension, but a multi dimensional
> mapping. This is the case for the OMI instrument, where a 2D-dectector
> is used for wavelength (columns of CCD) and a spatial dimension across
> the swath (rows of CCD). The mapping is imperfect, and the wavelength
> depends on the row-index.
>
> Note 2: Existing standard names supply aliases for these names:
> "toa_incoming_spectral_photon_solar_irradiance" and
> "toa_outgoing_spectral_photon_radiance" respectively.
>
> Note 3: mole as a unit for counting photons is unconventional within the
> satellite community, photon fluxes are typically expressed in 'photons
> cm-2 nm-1 s-1' and 'photons cm-2 nm-1 s-1 sr-1'. It would be nice to add
> 'photon' as an alias to UDUnits, in a way that is similar to the recent
> addition of 'molecule'.
>
> Note 4: Other instruments may use other units, depending on the
> construction of the instrument. These can not be converted easily into
> one another as they require additional knowledge, in particular
> knowledge of the wavelength. I'm unsure if UDUnits is equiped to handle
> these types of conversion. Additional names may be needed for using "W
> m-2 m-1" or "W m-2 m-1 sr-1" respectively (similar name, but leaving out
> the 'photon') Another quantity that is commonly encountered expresses
> the radiation_wavelength as wavenumber or frequency, and therefore also
> alters the (frequency/energy) interval over which the quantity is
> integrated. I'll leave the addition of these quantities to communities
> that actually use them, IASI on MetOp comes to mind.
>
> Kind regards,
>
> Maarten Sneep
--
Dr. Heiko Klein Tel. + 47 22 96 32 58
Development Section / IT Department Fax. + 47 22 69 63 55
Norwegian Meteorological Institute http://www.met.no
P.O. Box 43 Blindern 0313 Oslo NORWAY
Received on Tue Nov 18 2014 - 00:49:49 GMT
