VNP43DNBA2 v001

VIIRS/NPP DNB BRDF/Albedo Quality Daily L3 Global 1 km SIN Grid


PI: Crystal Schaaf

Description

The Suomi National Polar-Orbiting Partnership (S-NPP) NASA Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) Bidirectional Reflectance Distribution Function (BRDF) and Albedo Quality (VNP43DNBA2) Version 1 product provides BRDF and Albedo quality at 1 kilometer (km) resolution. The VNP43DNBA2 product is produced daily using 16 days of VIIRS data and is weighted temporally to the ninth day, which is reflected in the file name. The VNP43DNBA2 product gives information regarding band quality and days of valid observation within a 16-day period for the VIIRS DNB. The VNP43 data products are designed to promote the continuity of NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo data product suite.

The VNP43 algorithm uses the RossThick/Li-Sparse-Reciprocal (RTLSR) semi-empirical kernel-driven BRDF model, with the three kernel weights from VNP43DNBA1 to reconstruct surface anisotropic effects, correcting the directional reflectance to a common view geometry (VNP43DNBA4), while also computing integrated black-sky albedo (BSA) at local solar noon and white-sky albedo (WSA) (VNP43DNBA3). 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) layers 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 VNP43DNBA2 data product provides a total of seven SDS layers, including BRDF/Albedo band quality and days of valid observation within a 16-day period for the VIIRS DNB, as well as land water type class flag, snow BRDF albedo class flag, local solar noon, and the platform name.

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Characteristics

Product Maturity

Validation at stage 1 has been achieved for the VIIRS BRDF/Albedo product suite. Visit the VIIRS Land Product Quality Assessment website for additional information on validation and product maturity status.

Collection and Granule

Collection

Characteristic Description
CollectionS-NPP VIIRS
DOI10.5067/VIIRS/VNP43DNBA2.001
File Size~13 MB
Temporal ResolutionDaily
Temporal Extent2012-01-19 to Present
Spatial ExtentGlobal
Coordinate SystemSinusoidal
DatumN/A
File FormatHDF-EOS5
Geographic Dimensions1200 km x 1200 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers7
Columns/Rows1200 x 1200
Pixel Size1000 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
BRDF_Albedo_Band_Quality_DNB BRDF inversion information N/A 8-bit unsigned integer 255 N/A 0 to 3 N/A
BRDF_Albedo_LandWaterType Land/Water type Class Flag 8-bit unsigned integer 255 N/A 0 to 254 N/A
BRDF_Albedo_LocalSolarNoon Solar zenith angle at local solar noon Degree 8-bit unsigned integer 255 N/A 0 to 90 N/A
BRDF_Albedo_Platform Platform name N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A
BRDF_Albedo_Uncertainty Weight of Determination (WoD) of WSA N/A 16-bit unsigned integer 37267 N/A 0 to 32766 N/A
BRDF_Albedo_ValidObs_DNB Days of valid observation within 16-day period for band DNB N/A 16-bit unsigned integer 0 N/A 1 to 65535 N/A
Snow_BRDF_Albedo Snow Flag N/A 8-bit unsigned integer 255 N/A 0 to 1 N/A

Land/Water Type

Class Label Description
0 Shallow ocean
1 Land (Nothing else but land)
2 Ocean and lake shorelines
3 Shallow inland water
4 Ephemeral water
5 Deep inland water
6 Moderate or continental ocean
7 Deep ocean

Snow Flag

Class Label Description
0 snow-free albedo retrieved
1 snow albedo retrieved

Band Quality

Class Label Description
0 best quality, full inversion (WoDs, RMSE majority good)
1 good quality, full inversion
2 Magnitude inversion (numobs ≥ 7)
3 Magnitude inversion (numobs ≥ 2 & 7)
255 Fill value

Product Quality

Additional information on the quality layers can be found in Table 5 of the ATBD. Product accuracy/uncertainty information can be found in section 4.

Known Issues

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.

Documentation

Using the Data

Tools

Citation

DOI: 10.5067/VIIRS/VNP43DNBA2.001

About the Image

The BRDF albedo quality day/night band from the VNP43DNBA2 product over Algeria, Africa on October 1, 2019.

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