F. Nadal et Fm. Breon, Parameterization of surface polarized reflectance derived from POLDER spaceborne measurements, IEEE GEOSCI, 37(3), 1999, pp. 1709-1718
Citations number
22
Categorie Soggetti
Eletrical & Eletronics Engineeing
Journal title
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
Two months of spaceborne POLDER polarization measurements have been used to
generate empirical surface bidirectional polarization distribution functio
ns (BPDF's). Eleven surface classes have been defined based on a surface cl
assification and a vegetation index, Within each class, the surface polariz
ed reflectance was found rather homogeneous. The surface polarized reflecta
nce is highly anisotropic and varies between 0 close to the backscattering
direction, and a few percent in the forward scattering direction. For a giv
en observation geometry, the polarization is about twice as large over the
pixels classified as "desert" than over vegetated surfaces. An empirical fu
nction with two parameters fits the estimated surface polarized reflectance
with a residue on the order of 10(-3) in reflectance units. An analysis of
top-of-the-atmosphere (TOA) polarized reflectance over specific sunphotome
ter sites where the atmospheric contribution is well characterized confirms
the estimated accuracy of 10(-3).