Sorry,
I just had a look at the existing standard_names and toa is already
established there. So please ignore my last remark.
Heiko
On 2014-11-18 08:49, Heiko Klein wrote:
> 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 - 00:54:21 GMT
