The NOAA-21 Visible Infrared Imaging Radiometer Suite (VIIRS) Bidirectional Reflectance Distribution Function (BRDF) and Albedo Model Parameters (VJ243MA1) Version 2 product provides BRDF/Albedo model parameters at 1 kilometer (km) resolution. The VJ243MA1 product is produced daily using 16-day VIIRS data and is weighted temporally to the 9th day, which is reflected in the file name. The VJ243 data products are designed to promote the continuity of NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo data product suite.
The VJ243 algorithm uses the RossThick/Li-Sparse-Reciprocal (RTLSR) semi-empirical kernel-driven BRDF model, with the three kernel weights from VJ243MA1 to reconstruct surface anisotropic effects, correcting the directional reflectance to a common view geometry (VJ243MA4), while also computing integrated black-sky albedo (BSA) at local solar noon and white-sky albedo (WSA) (VJ423MA3). Researchers can use the BRDF model parameters with a simple polynomial, to obtain black-sky albedo at any solar illumination angle. Likewise, both the BSA and WSA Science Dataset (SDS) variables can be used with a simple polynomial, to manually estimate instantaneous actual albedo (blue-sky albedo). Additional details regarding the methodology are available in the Algorithm Theoretical Basis Document (ATBD).
The VJ243MA1 data product provides a total of 24 SDS variables including: mandatory quality bands and three multi-dimensional model parameter bands representing fiso, fvol, and fgeo for VIIRS moderate resolution bands M1-M5, M7-M8, and M10-M11. A low-resolution browse is also provided showing BRDF/Albedo parameters for bands M5, M7, and M5 as an RGB image in JPEG format.
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