Wednesday, 17 October 2001
Land Surface Albedo, Nadir BRDF-Adjusted Reflectance, and BRDF Products from the MODerate Resolution Imaging Spectroradiometer (MODIS)
Provisional albedo and bidirectional reflectance products of the
Earth's land surfaces from the MODerate resolution Imaging
Spectroradiometer (MODIS) on board NASA's Terra spacecraft have
been available since November 2000. Atmospherically corrected,
cloud cleared, surface reflectances are used to produce MODIS
Bidirectional Reflectance Distribution Function (BRDF), Nadir
BRDF-Adjusted surface Reflectance (NBAR), and Albedo Products
(MOD43B1, MOD43B3 and MOD43B4) every 16 days. The operational
MODIS BRDF/Albedo algorithm relies on multidate data and a
semiempirical kernel-driven bidirectional reflectance model
(RossThickLiSparseReciprocal) to determine a global set of
parameters describing the BRDF of the land surface. These one
kilometer gridded parameters are then used to determine global
directional hemispherical reflectance ("black-sky albedo"), and
bihemispherical reflectance ("white-sky albedo") for the first
seven spectral bands of MODIS and three broad bands of interest
to modelers. The parameters are also used to obtain the Nadir
BRDF-Adjusted surface Reflectances (NBAR) for the seven spectral
bands (at the mean solar zenith angle of the period). Due to
their stability, the NBAR data are subsequently used to serve as the primary input
for the MODIS Land Cover Product (MOD12Q1). The BRDF, NBAR and
Albedo Products are all being evaluated by the science team and
and a number of validation field exercises are now underway.
These provisional data sets are publically available from the EDC
DAAC.
Supplementary URL: http://geography.bu.edu/brdf/userguide/index.html