The Bidirectional Reflectance Distribution Function (BRDF)/Albedo parameters provide:
• coefficients for mathematical functions that describe the BRDF of each pixel in the seven MODIS 'Land' bands (1- 7); and
• albedo measurements derived simultaneously from the BRDF for bands 1-7 as well as three broad bands (0.4-0.7, 0.7-3.0, and 0.4- 3.0 micrometres).
The models support the spatial relationship and parameter characterization best describing the differences in radiation due to the scattering (anisotropy) of each pixel, relying on multi-date, atmospherically corrected, cloud-cleared input data measured over 16-day periods. Both Terra and Aqua data are used in the generation of this product, providing the highest probability for quality input data.
The MCD43A1 BRDF/Albedo Model Parameters Product (MODIS/Terra BRDF/Albedo Model_1 Daily L3 Global 500m SIN Grid) supplies the weighting parameters associated with the RossThickLiSparseReciprocal BRDF model that best describes the anisotropy of each pixel. These three parameters ( fiso , fvol , fgeo ) are provided for each of the MODIS spectral bands as well as for three broad bands (0.3-0.7µm, 0.7-5.0µm, and 0.3-5.0µm). These parameters can be used in a forward version of the model to reconstruct the surface anisotropic effects and thus correct directional reflectances to a common view geometry (this is the procedure that is used to produce MCD43A4 Nadir BRDF-Adjusted Reflectances - NBAR) or to compute the integrated black-sky (at some solar zenith angle) and white-sky albedos (as are done for MCD43A3). Alternately, the parameters can be used with a simple polynomial to easily estimate the black-sky albedo with good accuracy for any desired solar zenith angle.