S-NPP Product Descriptions: VNP43IA4N

Last update: November 20, 2023

Data Set Short Name:
VNP43IA4N

Data Set Long Name:
VIIRS/NPP Nadir BRDF-Adjusted Reflectance Daily L3 Global 500 m SIN Grid NRT

Platform:
Suomi National Polar-orbiting Partnership (S-NPP)

Instrument:
Visible Infrared Imaging Radiometer Suite (VIIRS)

Product Description:
The Near Real Time (NRT) Suomi National Polar-Orbiting Partnership (S-NPP) NASA Visible Infrared Imaging Radiometer Suite (VIIRS) Nadir Bidirectional Reflectance Distribution Function (BRDF) Adjusted Reflectance (NBAR), (VNP43IA4N) product provides NBAR estimates at 500 meter (m) resolution. The VNP43IA4N product is produced daily using 16-day VIIRS data (i.e., the current day and the previous 15 days). The view angle effects are removed from the directional reflectances resulting in a stable and consistent NBAR product. 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 VNP43IA1N to reconstruct surface anisotropic effects, correcting the directional reflectance to a common view geometry (VNP43IA4N), while also computing integrated black-sky albedo (BSA) at local solar noon and white-sky albedo (WSA) (VNP43MA3N). 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 VNP43IA4N product includes six SDS layers for BRDF/Albedo mandatory quality and nadir reflectance for VIIRS imagery bands I1, I2, and I3.

file_naming_convention = "VNP43IA4N.AYYYYDDD.hXXvYY.CCC.YYYYDDDHHMMSS.h5

• AYYYYDDD = Acquisition Year and Day of Year
• HHMM = Hour and minute of acquisition
• hXXvYY = Sinusoidal Tile Identifier (horizontalXXverticalYY)
• CCC = Collection Version number
• YYYYDDDHHMMSS = Julian Date and time of Production in Year, Day of Year, hour, minute, and seconds
• h5 = HDF-EOS (version 5) file format

Production Frequency:
~460 file per day

Spatial Coverage:
Global

Spatial Resolution:
500 m

File Size (MB):
~20

Citation:

Dataset Originator/Creator:
NASA Suomi-NPP Land Science Team/Land, Atmosphere Near real-time Capability for EOS (LANCE)Moderate Resolution Imaging Spectroradiometer (MODIS)

Data Authors:
Dr. Crystal B. Schaaf

Dataset DOI:
http://dx.doi.org/10.5067/VIIRS/VNP43IA4N.002