MOD13A2 v061

MODIS/Terra Vegetation Indices 16-Day L3 Global 1 km SIN Grid


PI: Kamel Didan

Description

The MOD13A2 Version 6.1 product provides Vegetation Index (VI) values at a per pixel basis at 1 kilometer (km) spatial resolution. There are two primary vegetation layers. The first is the Normalized Difference Vegetation Index (NDVI), which is referred to as the continuity index to the existing National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer (NOAA-AVHRR) derived NDVI. The second vegetation layer is the Enhanced Vegetation Index (EVI), which has improved sensitivity over high biomass regions. The algorithm for this product chooses the best available pixel value from all the acquisitions from the 16 day period. The criteria used is low clouds, low view angle and the highest NDVI/EVI value.

Provided along with the vegetation layers and the two quality assurance (QA) layers are reflectance bands 1 (red), 2 (near-infrared), 3 (blue), and 7 (mid-infrared), as well as four observation layers.

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Characteristics

Improvements/Changes from Previous Versions

  • The Version 6.1 Level-1B (L1B) products have been improved by undergoing various calibration changes that include: changes to the response-versus-scan angle (RVS) approach that affects reflectance bands for Aqua and Terra MODIS, corrections to adjust for the optical crosstalk in Terra MODIS infrared (IR) bands, and corrections to the Terra MODIS forward look-up table (LUT) update for the period 2012 - 2017.
  • A polarization correction has been applied to the L1B Reflective Solar Bands (RSB).

Product Maturity

Validation at stage 3 has been achieved for the MODIS Vegetation Index product suite. Further details regarding MODIS land product validation for the MOD13 data products are available from the MODIS Land Team Validation site.

Collection and Granule

Collection

Characteristic Description
CollectionTerra MODIS
DOI10.5067/MODIS/MOD13A2.061
File Size~9 MB
Temporal ResolutionMulti-Day
Temporal Extent2000-02-18 to Present
Spatial ExtentGlobal
Coordinate SystemSinusoidal
DatumN/A
File FormatHDF-EOS
Geographic Dimensions1200 km x 1200 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers12
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 NDVI 1 km 16 days NDVI NDVI 16-bit signed integer -3000 N/A -2000 to 10000 0.0001
1 km 16 days EVI 1 km 16 days EVI EVI 16-bit signed integer -3000 N/A -2000 to 10000 0.0001
1 km 16 days VI Quality VI Quality indicators Bit Field 16-bit unsigned integer 65535 N/A 0 to 65534 N/A
1 km 16 days red reflectance Surface Reflectance Band 1 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km 16 days NIR reflectance Surface Reflectance Band 2 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km 16 days blue reflectance Surface Reflectance Band 3 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km 16 days MIR reflectance Surface Reflectance Band 7 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km 16 days view zenith angle View zenith angle of VI Pixel Degree 16-bit signed integer -10000 N/A 0 to 18000 0.01
1 km 16 days sun zenith angle Sun zenith angle of VI pixel Degree 16-bit signed integer -10000 N/A 0 to 18000 0.01
1 km 16 days relative azimuth angle Relative azimuth angle of VI pixel Degree 16-bit signed integer -4000 N/A -18000 to 18000 0.01
1 km 16 days composite day of the year Day of year VI pixel Julian day 16-bit signed integer -1 N/A 1 to 366 N/A
1 km 16 days pixel reliability Quality reliability of VI pixel Rank 8-bit signed integer -1 N/A 0 to 4 N/A

Product Quality

The "1 km 16 days VI Quality" layer is stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the quality layer.

The QA bit flags for the "1 km 16 days pixel reliability" layer are provided in Table 4 and the "1km 16 days VI Quality" in Table 5 of the User Guide.

In areas where no valid VI is retrieved, VI Quality bits 11-13 are correctly assigned to indicate the land/water type. The other bits are set to 1 which can create a false notion of the parameter description; however, since no valid VI is retrieved these values can be ignored.

Known Issues

For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.

Documentation

Using the Data

Access Data

Citation

DOI: 10.5067/MODIS/MOD13A2.061

About the Image

Terra MODIS NDVI data from the MOD13A2 product over part of Brazil, July 27 - August 11, 2020.

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