User Guide
Algorithm Theoretical Basis Document (ATBD)
File Specification
The Terra Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Indices 16-Day (MOD13C1) Version 6.1 product provides a Vegetation Index (VI) value at a per pixel basis. 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 Climate Modeling Grid (CMG) consists 3,600 rows and 7,200 columns of 5,600 meter (m) pixels. Global MOD13C1 data are cloud-free spatial composites of the gridded 16-day 1 kilometer MOD13A2 data, and are provided as a Level 3 product projected on a 0.05 degree (5,600 m) geographic CMG. The MOD13C1 has data fields for NDVI, EVI, VI QA, reflectance data, angular information, and spatial statistics such as mean, standard deviation, and number of used input pixels at the 0.05 degree CMG resolution.
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.
| Characteristic | Description |
|---|---|
| Collection | Terra MODIS |
| DOI | 10.5067/MODIS/MOD13C1.061 |
| File Size | ~99 MB |
| Temporal Resolution | Multi-Day |
| Temporal Extent | 2000-02-18 to Present |
| Spatial Extent | Global |
| Coordinate System | Geographic Latitude and Longitude |
| Datum | N/A |
| File Format | HDF-EOS |
| Geographic Dimensions | Global |
| Characteristic | Description |
|---|---|
| Number of Science Dataset (SDS) Layers | 13 |
| Columns/Rows | 7200 x 3600 |
| Pixel Size | 5600 m |
| SDS Name | Description | Units | Data Type | Fill Value | No Data Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|---|
| CMG 0.05 Deg 16 days NDVI | 16 day NDVI | NDVI | 16-bit signed integer | -3000 | N/A | -2000 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days EVI | 16 day EVI | EVI | 16-bit signed integer | -3000 | N/A | -2000 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days VI Quality | VI quality indicators | Bit Field | 16-bit unsigned integer | 65535 | N/A | 0 to 65534 | N/A |
| CMG 0.05 Deg 16 days red reflectance | Surface Reflectance Band 1 | N/A | 16-bit signed integer | -1000 | N/A | 0 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days NIR reflectance | Surface Reflectance Band 2 | N/A | 16-bit signed integer | -1000 | N/A | 0 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days blue reflectance | Surface Reflectance Band 3 | N/A | 16-bit signed integer | -1000 | N/A | 0 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days MIR reflectance | Surface Reflectance Band 7 | N/A | 16-bit signed integer | -1000 | N/A | 0 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days Avg sun zen angle | View zenith angle of VI Pixel | Degree | 16-bit signed integer | -10000 | N/A | 0 to 18000 | 0.01 |
| CMG 0.05 Deg 16 days NDVI std dev | Standard deviation computed from input NDVI pixels | NDVI | 16-bit signed integer | -3000 | N/A | -2000 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days EVI std dev | Standard deviation computed from input EVI pixels | EVI | 16-bit signed integer | -3000 | N/A | -2000 to 10000 | 0.0001 |
| CMG 0.05 Deg 16 days #1km pix used | Number of 1 km input pixels used | Number | 8-bit unsigned integer | 255 | N/A | 0 to 36 | N/A |
| CMG 0.05 Deg 16 days #1km pix +-30deg VZ | Number of 1km pixels used with VZ angle less than + or - 30 degs | Number | 8-bit unsigned integer | 255 | N/A | 0 to 36 | N/A |
| CMG 0.05 Deg 16 days pixel reliabilty | Quality reliability of VI pixel | Rank | 8-bit signed integer | -1 | N/A | 0 to 4 | N/A |
The "CMG 0.05 Deg 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 "CMG 0.05 Deg 16 days pixel reliabilty" layer are provided in Table 18 and the "CMG 0.05 Deg 16 days VI Quality" layer in Tables 5 and 17 of the User Guide.
For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.