The MODIS Near Real Time (NRT) MCD43A1N, MODIS Combined Aqua and Terra Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameters is produced daily using 16 days of Terra and Aqua MODIS data. This global gridded tiled product provides model parameters/coefficients (isotropic, volume and surface) for characterizing the BRDF of each pixel at 500m resolution in the sinusoidal map projection. BRDF at each pixel for the current day is derived by inverting all available good quality corrected surface reflectance observations acquired by Terra and Aqua MODIS from the 16-day period ending with the current data day. The daily observation are weighed as a function of quality, observation coverage and temporal distance from the current data date. Model parameters are stored as 3D datasets for each of the 7 land bands, visible, near-infrared and shortwave bands along with corresponding mandatory QA flags. There is a significant change in the science algorithm of the Collection 61 (C61) NRT BRDF/Albedo products and, therefore significant differences/discontinuities between the C6 and C61 products. C61 algorithm changes are intended to minimize the differences between the NRT and Standard BRDF. The C61 NRT BRDF code has been modified to allow for an extra round of magnitude inversion, following a full inversion using the full set of inputs. This extra magnitude inversion will only use the set of 9 days that are overlapping between standard and NRT, with the highest weight being assigned to the last day.

Additional information at MODIS Land Science Team website at https://modis-land.gsfc.nasa.gov/brdf.html