Folks:
I am working the GOES-R program. We have a few very specific questions on the
use of a standard name (toa_bidirectional_reflectance):
The top of atmosphere (TOA) reflectance is a key product from satellite
observations but is
often ambiguous as a result of the many non-standard definitions used
throughout the
community. The CF standard name table includes "toa_bidirectional_reflectance"
as a unitless
quantity that is the ratio of the reflected to incident energy. However, the
details of this
quantity are not completely clear.
(1)
Does it include an integration of solid angle - i.e., introducing a factor of
PI for Lambertian surface? Does it include or exclude the cosine (SZA) factor
that is often omitted from imagery (and that allows a direct scaling from
radiance to
reflectance)?
(2) What programs have already adopted the "toa_bidirectional_reflectance" and
how can one ensure that the convention is being used consistently with respect
to the above questions?
very respectfully,
randy
