VNP13A2 v001

VIIRS/NPP Vegetation Indices 16-Day L3 Global 1 km SIN Grid


PI: Kamel Didan

Description

The Suomi National Polar-Orbiting Partnership (S-NPP) NASA Visible Infrared Imaging Radiometer Suite (VIIRS) Vegetation Indices (VNP13A2) Version 1 data product provides vegetation indices by a process of selecting the best available pixel over a 16-day acquisition period at 1 kilometer (km) resolution. The VNP13 data products are designed after the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua Vegetation Indices product suite to promote the continuity of the Earth Observation System (EOS) mission.

The VNP13 algorithm process produces three vegetation indices: The Normalized Difference Vegetation Index (NDVI), the Enhanced Vegetation Index (EVI), and the Enhanced Vegetation Index-2 (EVI2). NDVI is one of the longest continual remotely sensed time series observations, using both the red and near-infrared (NIR) bands. EVI is a slightly different vegetation index that is more sensitive to canopy cover, while NDVI is more sensitive to chlorophyll. EVI2 is a reformation of the standard 3-band EVI, using the red band and NIR band. This reformation addresses arising issues when comparing VIIRS EVI to other EVI models that do not include a blue band. EVI2 will eventually become the standard EVI.

Along with the three Vegetation Indices layers, this product also includes layers for NIR reflectance; three shortwave infrared (SWIR) reflectance; red, blue, and green reflectance; composite day of year; pixel reliability; relative azimuth, view, and sun angles, and a quality layer. Two low resolution browse images are also available for each VNP13A2 product: EVI and NDVI.

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Characteristics

Product Maturity

Validation at stage 1 has been achieved for the VIIRS Vegetation Index (VI) product suite. Visit VIIRS Land Product Quality Assessment Product Maturity for information on product maturity status.

Collection and Granule

Collection

Characteristic Description
CollectionS-NPP VIIRS
DOI10.5067/VIIRS/VNP13A2.001
File Size~30 MB
Temporal ResolutionMulti-Day
Temporal Extent2012-01-17 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) Layers16
Columns/Rows1200 x 1200
Pixel Size1000 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
1 km 16 days EVI 3 band Enhanced Vegetation Index EVI 16-bit signed integer -15000, -13000 N/A -10000 to 10000 10000
1 km 16 days EVI2 2 band Enhanced Vegetation Index EVI2 16-bit signed integer -15000, -13000 N/A -10000 to 10000 10000
1 km 16 days NDVI Normalized Difference Vegetation Index NDVI 16-bit signed integer -15000, -13000 N/A -10000 to 10000 10000
1 km 16 days NIR reflectance Near-infrared Radiation reflectance (846–885 nm) N/A 16-bit signed integer -1000 N/A 0 to 10000 10000
1 km 16 days SWIR1 reflectance Shortwave Infrared Radiation reflectance (1230–1250 nm) N/A 16-bit signed integer -1000 N/A 0 to 10000 10000
1 km 16 days SWIR2 reflectance Shortwave Infrared Radiation reflectance (1580–1640 nm) N/A 16-bit signed integer -1000 N/A 0 to 10000 10000
1 km 16 days SWIR3 reflectance Shortwave Infrared Radiation reflectance (2225–2275 nm) N/A 16-bit signed integer -1000 N/A 0 to 10000 10000
1 km 16 days VI Quality Bit field that assigns each pixel a Quality Assessment (QA) attribute Bit Field 16-bit unsigned integer 65535 N/A 0 to 65534 N/A
1 km 16 days blue reflectance Blue band reflectance (478–498 nm) N/A 16-bit signed integer -1000 N/A 0 to 10000 10000
1 km 16 days composite day of the year Day of year for the pixel Julian day 16-bit signed integer -1 N/A 1 to 366 N/A
1 km 16 days green reflectance Green band reflectance (545–565 nm) N/A 16-bit signed integer -1000 N/A 0 to 10000 10000
1 km 16 days pixel reliability Pixel usefulness using a simple rank class Rank 8-bit signed integer -4, -1 N/A 0 to 11 N/A
1 km 16 days red reflectance Red band reflectance (600–680 nm) N/A 16-bit signed integer -1000 N/A 0 to 10000 10000
1 km 16 days relative azimuth angle Relative azimuth angle for each pixel Degree 16-bit signed integer -20000 N/A -18000 to 18000 100
1 km 16 days sun zenith angle Sun zenith angle for each pixel Degree 16-bit signed integer -20000 N/A 0 to 18000 100
1 km 16 days view zenith angle View zenith angle for each pixel Degree 16-bit signed integer -20000 N/A 0 to 18000 100

All scale factors are to be divided.

Fill Values for the Vegetation Index Layers

Fill Value Description
-15000 over ocean/water
-13000 over land

Fill Values for the Pixel Reliability Layer

Fill Value Description
-4 over ocean/water
-1 over land

Product Quality

Product Quality information can be found in the combined User Guide and Algorithm Theoretical Basis Document (ATBD). For the “1 km monthly pixel reliability” SDS Layer, a rank quality table for each pixel can be found in Table 5 on page 35. For the “1 km monthly VI Quality” SDS Layer, for use with all VI’s, a bit field Quality Assurance table can be found in Table 13 on pages 43-44, with additional information available in Table 20 on page 53. Accuracy Precision and Uncertainty information is available on page 65.

Known Issues

Known issues for VNP13A2 are available on the VIIRS Land Product Quality Assessment website.

Documentation

Using the Data

E-Learning

Land Ho! Exploring Earth’s Land Surface with Suomi NPP NASA VIIRS Land Data

Tools

Citation

DOI: 10.5067/VIIRS/VNP13A2.001

About the Image

The VNP13A2 vegetation indices product over Brazil, July 21 - August 5, 2018.

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