The Suomi National Polar-Orbiting Partnership (S-NPP) NASA Visible Infrared Imaging Radiometer Suite (VIIRS) Bidirectional Reflectance Distribution Function (BRDF) and Albedo Model Parameter 2 Band M8 product (VNP43D20) is produced daily using 16 days of data at 30 arc second (1,000 meter) resolution. Data are temporally weighted to the ninth day, which is reflected in the file name. The VNP43D product suite is provided in a Climate Modeling Grid (CMG), which covers the entire globe for use in climate simulation models. Due to the large file size, each VNP43D product contains just one data layer. Each of the three model parameters (isotropic, volumetric, and geometric) for each of the nine VIIRS moderate resolution bands along with the visible, near-infrared (NIR), and shortwave bands included in the VNP43MA1 product is stored in a separate file as VNP43D01 through VNP43D36. In addition to the bands included in VNP43MA1, this product suite includes model parameters for the VIIRS Day/Night Band (DNB) as VNP43D37 through VNP43D39. Details regarding methodology are available on the VNP43MA1 product page and in the Algorithm Theoretical Basis Document (ATBD).
VNP43D20 is the BRDF volumetric parameter for VIIRS band M8 (1.240 μm). The volumetric parameter, in conjunction with the isotropic and geometric parameters, is used to derive the BRDF/Albedo values for VIIRS band M8.
|File Size||~200 MB|
|Temporal Extent||2012-01-19 to Present|
|Coordinate System||Geographic Latitude and Longitude|
|Number of Science Dataset (SDS) Layers||1|
|Columns/Rows||43200 x 21600|
|Pixel Size||1000 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|BRDF_Albedo_Parameter2_M8||BRDF model parameter for vol kernel of Band M8||N/A||16-bit signed integer||32767||N/A||0 to 32766||0.001|
The VIIRS Land Surface Reflectance product (VNP09) flags a larger number of retrievals as ‘High Aerosol’ in the quality layer as compared to the MODIS reflectance product. The inaccurately flagged high aerosol quality flags cause the BRDF retrieval algorithm to incorrectly reject the observations and switch from full inversion (high quality retrieval) to magnitude inversion (low quality retrieval) in the mid to high latitude, arid lands, and tropical vegetative regions.