The MYD13Q1 images shown are samples of the MODIS/Aqua Vegetation Indices 16-Day L3 Global 250m SIN Grid product. The NDVI and EVI have been pseudo-colored to represent biomass health in using tile h22v10 from June 18 July 3, 2007.
Due to their simplicity, ease of application, and widespread familiarity, vegetation indices have a wide range of usage within the user community. Some of the more common applications may include global biogeochemical and hydrologic modeling, agricultural monitoring and forecasting, land-use planning, land cover characterization, and land cover change detection.
Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared reflectances, centered at 469-nanometers, 645-nanometers, and 858-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 time series historical applications. MODIS also includes a new Enhanced Vegetation Index (EVI) that minimizes canopy background variations and maintains sensitivity over dense vegetation conditions. The EVI also uses the blue band to remove residual atmosphere contamination caused by smoke and sub-pixel thin cloud clouds. The MODIS NDVI and EVI products are computed from atmospherically corrected bi-directional surface reflectances that have been masked for water, clouds, heavy aerosols, and cloud shadows.
Global MYD13Q1 data are provided every 16 days at 250-meter spatial resolution as a gridded level-3 product in the Sinusoidal projection. Lacking a 250m blue band, the EVI algorithm uses the 500m blue band to correct for residual atmospheric effects, with negligible spatial artifacts.
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 and global and regional climate. These data also may be used for characterizing land surface biophysical properties and processes, including primary production and land cover conversion.
Version-5 MODIS/Aqua Vegetation Indices products are Validated Stage 2, meaning that accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts. Although there may be later improved versions, these data are ready for use in scientific publications.
Temporal Coverage | July 4, 2002 - |
Area | ~10 x 10 lat/long |
File Size | ~ 93 MB |
Projection | Sinusoidal |
Data Format | HDF-EOS |
Dimensions | 4800 x 4800 rows/columns |
Resolution | 250 meters |
Science Data Sets (SDS HDF Layers) | 12 |
Science Data Sets for MODIS Aqua Vegetation Indices 16-Day L3 Global 250m SIN Grid V005 (MYD13Q1):
Science Data Sets |
UNITS |
BIT TYPE |
FILL |
VALID RANGE |
MULTIPLY BY SCALE FACTOR |
---|---|---|---|---|---|
250m 16 days NDVI | NDVI | 16-bit signed integer | -3000 | -2000, 10000 | 0.0001 |
250m 16 days EVI | EVI | 16-bit signed integer | -3000 | -2000, 10000 | 0.0001 |
250m 16 days VI Quality detailed QA | Bits | 16-bit unsigned integer | 65535 | 0, 65534 | NA |
250m 16 days red reflectance (Band 1) | Reflectance | 16-bit signed integer | -1000 | 0, 10000 | 0.0001 |
250m 16 days NIR reflectance (Band 2) | Reflectance | 16-bit signed integer | -1000 | 0, 10000 | 0.0001 |
250m 16 days blue reflectance (Band 3) | Reflectance | 16-bit signed integer | -1000 | 0, 10000 | 0.0001 |
250m 16 days MIR reflectance (Band 7) | Reflectance | 16-bit signed integer | -1000 | 0, 10000 | 0.0001 |
250m 16 days view zenith angle | Degree | 16-bit signed integer | -10000 | -9000, 9000 | 0.01 |
250m 16 days sun zenith angle | Degree | 16-bit signed integer | -10000 | -9000, 9000 | 0.01 |
250m 16 days relative azimuth angle | Degree | 16-bit signed integer | -4000 | -3600, 3600 | 0.1 |
250m 16 days composite day of the year | Julian day of year | 16-bit signed integer | -1 | 1, 366 | NA |
250m 16 days pixel reliability summary QA | Rank | 8-bit signed integer | -1 | 0, 3 | NA |
The QA information below is excerpted from the Quality Science Data Set within an HDF-EOS MOD13Q1 file.
A summary Quality layer has been included in the MOD13Q1: “pixel reliability.” This layer contains ranked values describing overall pixel quality (Table 1 below).
Because evaluation of the past 6 years of V003 and V004 data collections revealed insignificant differences between the Quality assignments for NDVI versus EVI, the V005 MOD13 products include a single Quality layer pertinent to both indices (Table 2 below), rather than one layer for each. This reduces data volume as well as user confusion with multiple Quality layers.
TABLE 1: MOD13Q1 Pixel Reliability
Rank Key |
Summary QA |
Description |
---|---|---|
-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 |
TABLE 2: MOD13Q1 VI Quality
Bit 0 is the least significant (read bit words right to left)
bit |
Long Name |
Value |
Key |
---|---|---|---|
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 |
0001 | Lower quality | ||
0010 | Decreasing quality | ||
0100 | Decreasing quality | ||
1000 | Decreasing quality | ||
1001 | Decreasing quality | ||
1010 | Decreasing quality | ||
1100 | Lowest quality | ||
1101 | Quality so low that it is not useful | ||
1110 | L1B data faulty | ||
1111 | Not useful for any other reason/not processed | ||
6–7 | Aerosol quantity | 00 | Climatology |
01 | Low | ||
10 | Average | ||
11 | High | ||
8 | Adjacent cloud detected | 1 | Yes |
0 | No | ||
9 | Atmosphere BRDF correction performed | 1 | Yes |
0 | No | ||
10 | Mixed Clouds | 1 | Yes |
0 | No | ||
11–13 | Land/Water Flag | 000 | Shallow ocean |
001 | Land (Nothing else but land) | ||
010 | Ocean coastlines and lake shorelines | ||
011 | Shallow inland water | ||
100 | Ephemeral water | ||
101 | Deep inland water | ||
110 | Moderate or continental ocean | ||
111 | Deep ocean | ||
14 | Possible snow/ice | 1 | Yes |
0 | No | ||
15 | Possible shadow | 1 | Yes |
0 | No |
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In the event that data distributed from the Land Processes DAAC are incorporated into your research, please supply the following acknowledgment within your published work: "These data are distributed by the Land Processes Distributed Active Archive Center (LP DAAC), located at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center (lpdaac.usgs.gov)." If possible, please e-mail or send us reprints/citations of papers or oral presentations based on data obtained from the LP DAAC (see below for mailing address and e-mail address). This will help us to stay informed of how the data are being utilized.
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Sioux Falls, SD 57198-0001
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U.S. Geological Survey (USGS)
Center for Earth Resources Observation and Science (EROS)
47914 252nd Street
Sioux Falls, SD 57198-0001
Phone Number: | 605-594-6116 |
Toll Free: | 866-573-3222 |
866-LPE-DAAC | |
Fax: | 605-594-6963 |
Email: | lpdaac@eos.nasa.gov |
Web: | http://lpdaac.usgs.gov |