MOD13A3 v006

MODIS/Terra Vegetation Indices Monthly L3 Global 1 km SIN Grid

PI: Kamel Didan

The MOD13A3 Version 6 data product was decommissioned on July 31, 2023. Users are encouraged to use the MOD13A3 Version 6.1 data product.


The Terra Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Indices (MOD13A3) Version 6 data are provided monthly at 1 kilometer (km) spatial resolution as a gridded Level 3 product in the sinusoidal projection. In generating this monthly product, the algorithm ingests all the MOD13A2 products that overlap the month and employs a weighted temporal average.

The MODIS Normalized Difference Vegetation Index (NDVI) complements NOAA's Advanced Very High Resolution Radiometer (AVHRR) NDVI products and provides continuity for time series historical applications. MODIS also includes an Enhanced Vegetation Index (EVI) that minimizes canopy background variations and maintains sensitivity over dense vegetation conditions. The EVI uses the blue band to remove residual atmosphere contamination caused by smoke and sub-pixel thin clouds. The MODIS NDVI and EVI products are computed from surface reflectances corrected for molecular scattering, ozone absorption, and aerosols.

Vegetation indices are used for global monitoring of vegetation conditions and are used in products displaying land cover and land cover changes. These data may be used as input for modeling global biogeochemical and hydrologic processes as well as global and regional climate. Additional applications include characterizing land surface biophysical properties and processes, such as primary production and land cover conversion.

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 three observation layers.

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Improvements/Changes from Previous Versions

  • The 16-day composite VI is generated using the two 8-day composite surface reflectance granules (MOD09A1) in the 16-day period.
  • This surface reflectance input is based on the minimum blue compositing approach used to generate the 8-day surface reflectance product.
  • The product format is consistent with the Version 5 product generated using the Level 2 gridded daily surface reflectance product.
  • A frequently updated long-term global Climate Modeling Grid (CMG) Average Vegetation Index product database is used to fill the gaps in the CMG product suite.

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


Characteristic Description
CollectionTerra MODIS
File Size~8.29 MB
Temporal ResolutionMonthly
Temporal Extent2000-02-01 to 2023-01-31
Spatial ExtentGlobal
Coordinate SystemSinusoidal
File FormatHDF-EOS
Geographic Dimensions1200 km x 1200 km


Characteristic Description
Number of Science Dataset (SDS) Layers11
Columns/Rows1200 x 1200
Pixel Size1000 m

Layers / Variables

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
1 km monthly NDVI 1 km monthly NDVI NDVI 16-bit signed integer -3000 N/A -2000 to 10000 0.0001
1 km monthly EVI 1 km monthly EVI EVI 16-bit signed integer -3000 N/A -2000 to 10000 0.0001
1 km monthly VI Quality VI Quality indicators Bit Field 16-bit unsigned integer 65535 N/A 0 to 65534 N/A
1 km monthly red reflectance Surface Reflectance Band 1 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km monthly NIR reflectance Surface Reflectance Band 2 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km monthly blue reflectance Surface Reflectance Band 3 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km monthly MIR reflectance Surface Reflectance Band 7 N/A 16-bit signed integer -1000 N/A 0 to 10000 0.0001
1 km monthly view zenith angle View zenith angle of VI Pixel Degree 16-bit signed integer -10000 N/A 0 to 18000 0.01
1 km monthly sun zenith angle Sun zenith angle of VI pixel Degree 16-bit signed integer -10000 N/A 0 to 18000 0.01
1 km monthly relative azimuth angle Relative azimuth angle of VI pixel Degree 16-bit signed integer -4000 N/A -18000 to 18000 0.01
1 km monthly pixel reliability Quality reliability of VI pixel Rank 8-bit signed integer -1 N/A 0 to 3 N/A

Product Quality

The QA bit flags for the "1 km monthly pixel reliability" layer are provided in Table 4 on page 15 and the "1 km monthly VI Quality" layer in Table 5 on page 16 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.

Quality assurance information should be considered when determining the usability of data for a particular science application. The ArcGIS MODIS-VIIRS Python Toolbox contains tools capable of decoding quality data layers while producing thematic quality raster files for each quality attribute.

In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the quality layers.

The "1 km monthly 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.

Known Issues

The incorrect representation of the aerosol quantities (low, average, high) in the Collection 6 MOD09 surface reflectance products may have impacted MOD13 Vegetation Index data products particularly over arid bright surfaces.

Corrections were implemented in Collection 6.1 reprocessing.

For complete information about the MOD13A3 known issues please refer to the MODIS Land Quality Assessment website.

About the image

Terra MODIS NDVI data from the MOD13A3 product over part of Brazil, July 2018.

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User Guide
Algorithm Theoretical Basis Document (ATBD)
File Specification

Using the Data

Access Data


DOI: 10.5067/MODIS/MOD13A3.006