MODIS/Aqua Vegetation Indices Monthly L3 Global 1km SIN Grid
MYD13A3
Version
Acquisition Range
Science Quality Status
V004
August 1, 2002 (2002213)
No status available
MODIS Level 3 Tile h08v05, July 12 2002
Data Set Characteristics
Area = ~ 10° x 10° lat/long
Image Dimensions = 2 (1200x1200 row/column)
Average File Size = 32 MB
Resolution = 1 km
Projection = Sinusoidal
Data Format = HDF-EOS
Science Data Sets (SDSs) = 11
Product Description
The MODerate-resolution Imaging Spectroradiometer (MODIS) Vegetation Indices products use, as input, MODIS Aqua surface reflectances (MYD09) corrected for molecular scattering, ozone absorption, and aerosols. Two vegetation index (VI) algorithms are produced globally for land. One is the standard normalized difference vegetation index (NDVI), which is referred to as the "continuity index" to the existing NOAA-AVHRR derived NDVI. The other is an 'enhanced' vegetation index (EVI) with improved sensitivity into high biomass regions and improved vegetation monitoring through a de-coupling of the canopy background signal and a reduction in atmosphere influences. The two VIs compliment each other in global vegetation studies and improve upon the extraction of canopy biophysical parameters. A new compositing scheme that reduces angular, sun-target-sensor variations with an option to use BRDF models is utilized. The gridded vegetation indices include quality assurance (QA) flags with statistical data that indicate the quality of the VI product and input data.
The MODIS/Aqua Vegetation Indices Monthly L3 Global 1km SIN Grid (MYD13A3) is temporally averaged from all surface reflectance data available in the16-day MODIS VI products (a maximum of 3) that overlap the calendar month. Each input 16-day product (MYD13A2) is weighted by the number of actual days that overlap the month being processed. The algorithm first produces monthly surface reflectance from the red, near-infrared (NIR), blue and mid-infrared (MIR) data in the MYD13A2, then derives the monthly VI. A worst-case scenario is used to generate the per-pixel quality information.
The MYD13A3 images shown are pseudo-colored samples of NDVI and EVI representing the biomass health of the western United States using tile h08v05 from July 12, 2002. 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.
NOTE: These products are still experimental in nature upon their initial release. Investigations are underway to assess the scientific validity of these products.
Each VI product contains 11 parameters, listed below:
SDS
Units
Data Type-bit
Fill Value
Valid Range
Divide by SCALE FACTOR
1km monthly NDVI
NDVI
16-bit signed integer
-3000
-2000 - 10000
10000
1km monthly EVI
EVI
16-bit signed integer
-3000
-2000 - 10000
10000
*1km monthly NDVI Quality
bit field
16-bit unsigned integer
65535
0 -v65535
na
*1km monthly EVI Quality
bit field
16-bit unsigned integer
65535
0 -v65535
na
1km monthly red reflectance MODIS Band # 1, 620 - 670 nm
reflectance
16-bit signed integer
-1000
0 - 10000
10000
1km monthly NIR reflectance MODIS Band # 2, 841- 876 nm
reflectance
16-bit signed integer
-1000
0 - 10000
10000
1km monthly blue reflectance MODIS Band # 3, 459 - 479 nm
reflectance
16-bit signed integer
-1000
0 - 10000
10000
1km monthly MIR reflectance MODIS Band # 7, 2105-2155 nm
reflectance
16-bit signed integer
-1000
0 - 10000
10000
1km monthly average view zenith angle View zenith of the chosen pixel
degree
16-bit signed integer
-10000
-9000 - 9000
100
1km monthly average sun zenith angle Sun zenith of the chosen pixel
degree
16-bit signed integer
-10000
-9000 - 9000
100
1km monthly average relative azimuth angle Relative Azimuth of the chosen pixel
LP DAAC User Services
U.S. Geological Survey (USGS)
Earth Resources Observation and Science Center (EROS)
47914 252nd Street
Sioux Falls, SD 57198-0001