The Suomi National Polar-Orbiting Partnership (S-NPP) NASA Visible Infrared Imaging Radiometer Suite (VIIRS) Bidirectional Reflectance Distribution Function (BRDF) and Albedo Model Parameter 3 Shortwave product (VNP43D36) 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).
VNP43D36 is the BRDF geometric parameter for VIIRS shortwave broadband (1.61 μm). The geometric parameter, in conjunction with the isotropic and volumetric parameters, is used to derive the BRDF/Albedo values for the VIIRS shortwave broadband.
|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_Parameter3_shortwave||BRDF model parameter for geo kernel of shortwave Band||N/A||16-bit signed integer||32767||N/A||0 to 32766||0.001|
The abnormally high activation of the high aerosol flag in the Collection 1 (C1) VNP09 product, has impacted downstream products. The VNP43 BRDF/Albedo/NBAR product is affected by reducing the number of otherwise acceptable observations used as input to characterize surface anisotropy. This effect (most obvious over arid bright surfaces), results in a reduced number of high quality full BRDF model inversions. Therefore, users should be aware that bright arid surfaces (normally associated with high quality BRDF/Albedo/NBAR retrievals) are likely to be somewhat represented by lower quality results in C1. VNP09 has been corrected for Collection 2 (C2). Therefore, users should avoid substantive use of C1 VNP43 over arid regions (and wait for C2 products). In any event, users are always strongly encouraged to download and use the extensive QA data provided in VNP43[I-M]A2, in addition to the briefer mandatory QA provided as part of the VNP43[I-M]A1, 3 and 4 products.
Additional known issues for VNP43 data products can be found on the VIIRS Land Quality Assessment website.