Below are the updated descriptions for the two proposed standard names.
Note CF does not seem to have a definition for albedo though it is used
in a handful of standard_names.
-ted
“toa_lambertian_equivalent_albedo”
“Albedo is the ratio of the outgoing to the incoming power per unit area
(irradiance). A coordinate variable can be used to specify the radiation
wavelength or frequency. ‘toa’ means top of atmosphere.
‘lambertian_equivalent’ means the quantity is evaluated for a diffusely
reflecting surface.”
canonical units = 1
“toa_lambertian_equivalent_albedo_multiplied_by_cosine_solar_zenith_angle”
“Albedo is the ratio of the outgoing to the incoming power per unit area
(irradiance). A coordinate variable can be used to specify the radiation
wavelength or frequency. ‘toa’ means top of atmosphere.
‘lambertian_equivalent’ means the quantity is evaluated for a diffusely
reflecting surface. ‘multiplied_by_cosine_solar_zenith_angle’ means that
the quantity has normalized to remove the angular dependence of the
incoming shortwave irradiance”
canonical units = 1
Jonathan Gregory wrote:
Dear Ted
Thanks for this explanation:
Reflectance is the ratio of outgoing radiance to incoming irradiance
giving it units of per steradians.
Albedo is the ratio of outgoing irradiance to incoming irradiance
and is unitless.
Because the proposed quantity is unitless, albedo is the better term.
However, albedo is the integral over all angles of the bidirectional
reflectance. In general, true
planetary albedo would account for this angular dependence. To make clear the
assumption regarding the Lambertian surface I still propose using the term
Lambertian equivalent in the name. Thus:
toa_lambertian_equivalent_albedo
toa_lambertian_equivalent_albdeo_multiplied_by_cosine_solar_zenith_angle
OK, with small L in lambertian as you had before (because stdnames are all
in lower case). Thanks!
Cheers
Jonathan
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