The image above is a global 16-day composite of the MODIS Normalized Difference Vegetation Index (NDVI) included in the MYD13C1 product. The NDVI values have been pseudo-colored to represent biomass health across the globe using data acquired between July 20 and August 4, 2007.
Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared reflectances, centered at 470-nanometers, 648-nanometers, and 848-nanometers, respectively, are used to determine the MODIS daily vegetation indices.
The MODIS Normalized Difference Vegetation Index (NDVI) complements NOAA's Advanced Very High Resolution Radiometer (AVHRR) NDVI products and provides continuity for historical applications. The MODIS NDVI product contains atmospherically corrected bi-directional surface reflectances masked for water, clouds, and cloud shadows. Another MODIS index, the Enhanced Vegetation Index or EVI, uses the blue band to remove residual atmospheric contamination caused by smoke and sub-pixel thin clouds. The EVI also uses feedback adjustment to minimize canopy background variations and to enhance vegetation sensitivity from sparse to dense vegetation conditions.
Global MYD13C1 data are cloud-free spatial composites of the gridded 16-day 1-kilometer MYD13A2, and are provided as a level-3 product projected on a 0.05 degree (5600-meter) geographic Climate Modeling Grid (CMG). Cloud-free global coverage is achieved by replacing clouds with the historical MODIS time series climatology record.
Vegetation indices are used for globally monitoring 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 and global and regional climate. These data also may be used for characterizing land surface biophysical properties, including land cover.
Version-5 MODIS Vegetation Indices products have attained Validation Stage 3.
See Product Description
Science Data Sets for MODIS Aqua Vegetation Indices 16-Day L3 Global 0.05Deg CMG V005 (MYD13C1):
Science Data Sets (HDF Layers) (13)
MULTIPLY BY SCALE FACTOR
|CMG 0.05 Deg 16 days NDVI||NDVI||16-bit signed integer||-3000||-2000,10000||0.0001|
|CMG 0.05 Deg 16 days EVI||EVI||16-bit signed integer||-3000||-2000, 10000||0.0001|
|CMG 0.05 Deg 16 days VI Quality||Bit Field||16-bit unsigned integer||65535||0, 65534||NA|
|CMG 0.05 Deg 16 days red reflectance (Band 1)||Reflectance||16-bit signed integer||-1000||0, 10000||0.0001|
|CMG 0.05 Deg 16 days NIR reflectance (Band 2)||Reflectance||16-bit signed integer||-1000||0, 10000||0.0001|
|CMG 0.05 Deg 16 days blue reflectance (Band 3)||Reflectance||16-bit signed integer||-1000||0, 10000||0.0001|
|CMG 0.05 Deg 16 days MIR reflectance (Band 7)||Reflectance||16-bit signed integer||-1000||0, 10000||0.0001|
|CMG 0.05 Deg 16 days Avg sun zenith angle||Degree||16-bit signed integer||-10000||-9000, 9000||0.01|
|CMG 0.05 Deg 16 days NDVI std dev||NDVI||16-bit signed integer||-3000||-2000–10000||0.0001|
|CMG 0.05 Deg 16 days EVI std dev||EVI||16-bit signed integer||-3000||-2000–10000||0.0001|
|CMG 0.05 Deg 16 days #1km pix used||Pixels||8-bit unsigned integer||255||0–36||1.0|
|CMG 0.05 Deg 16 days #1km pix +-30deg VZ||Pixels||8-bit unsigned integer||255||0–36||1.0|
|CMG 0.05 Deg 16 days pixel reliability||Rank||8-bit signed integer||-1||0–4||1.0|
The QA information below is excerpted from the Quality Science Data Set within an HDF-EOS MOD13C1 file.
A summary Quality layer has been included in the MOD13C1: “pixel reliability.” This layer contains ranked values describing overall pixel quality (Table 1 below).
TABLE 1: MYD13C1 Pixel Reliability
|-1||Fill/No Data||Not Processed|
|0||Good Data||Use with confidence|
|1||Marginal data||Useful, but look at other QA information|
|2||Snow/Ice||Target covered with snow/ice|
|3||Cloudy||Target not visible, covered with cloud|
|4||Estimated||From MODIS historic time series|
TABLE 2: MYD13C1 VI Quality
Bit 0 is the least significant (read bit words right to left)
|0–1||MODLAND_QA||00||VI produced, good quality|
|01||VI produced, but check other QA|
|10||Pixel produced, but most probably cloudy|
|11||Pixel not produced due to other reasons than clouds|
|2–5||VI usefulness||0000||Highest quality|
|1101||Quality so low that it is not useful|
|1110||L1B data faulty|
|1111||Not useful for any other reason/not processed|
|8||Adjacent cloud detected||1||Yes|
|9||Atmosphere BRDF correction performed||1||Yes|
|11–13||Land/Water Flag||000||Shallow ocean|
|001||Land (Nothing else but land)|
|010||Ocean coastlines and lake shorelines|
|011||Shallow inland water|
|101||Deep inland water|
|110||Moderate or continental ocean|
|14–15||Geospatial quality||00||<= 25% of the finer 1km resolution contributed to this CMG pixel|
|01||>25% and <= 50% of the finer 1km resolution contributed to this CMG pixel|
|10||>50% and <= 75% of the finer 1km resolution contributed to this CMG pixel|
|11||>75% and <=100% of the finer 1km resolution contributed to this CMG pixel|
|Temporal Coverage||July 4, 2002 -|
|File Size||~100 MB|
|Dimensions||3600 x 7200 rows/columns|
|Resolution||0.05 degree (5600-meter)|
|Science Data Sets (SDS HDF Layers)||13|
Please find the current MODIS-related Data policies on the MODIS Policies page at https://lpdaac.usgs.gov/products/modis_policies.
For information on how to cite LP DAAC data, please see our Data Citations page at https://lpdaac.usgs.gov/about/citing_lp_daac_and_data.
Data Pool: The Data Pool (On-line Archive) provides access to all MODIS products, and a rolling archive of ASTER level-1B products that cover the U.S. and its Territories.
Reverb: This tool provides access to a complete data record of all MODIS and ASTER products available from the LP DAAC.
The Data Access section of this Web site also provides access to these interfaces.
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