The MYD13A3 Version 6 data product was decommissioned on July 31, 2023. Users are encouraged to use the MYD13A3 Version 6.1 data product.

The Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Indices (MYD13A3) 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 MYD13A2 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.

Known Issues

• The incorrect representation of the aerosol quantities (low, average, high) in the Collection 6 MYD09 surface reflectance products may have impacted MYD13 Vegetation Index data products particularly over arid bright surfaces.
• Corrections were implemented in Collection 6.1 reprocessing.
• For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.

Improvements/Changes from Previous Versions

• The 16-day composite VI is generated using the two 8-day composite surface reflectance granules (MYD09A1) 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.