LP DAAC MODIS FAQ

• What is MODIS/Terra Vegetation Indices 16-Day L3 Global 1km SIN Grid?
• What are the specifications of the MODIS/Terra Vegetation Indices 16-Day L3 Global 1km SIN Grid?
• What formats are available?
• What is the coverage area?
• Where can more information be found about MODIS/Terra Vegetation Indices 16-Day L3 Global 1km SIN Grid?

A. LP DAAC MOD13A2 (MODIS/Terra Vegetation Indices 16-Day L3 Global 1km SIN Grid) The MOD13A2 product is a MODIS Level 3 16-day composite of Vegetation indices at 1km resolution. This product uses, as input, MODIS Terra surface reflectances, 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 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 is also utilized.

The gridded vegetation indices will include quality assurance (QA) flags with statistical data that indicate the quality of the VI product and input data. Due to their simplicity, ease of application, and widespread familiarity, vegetation indices have a wide range of use 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 validated, meaning that product uncertainties are well defined over a range of representative conditions. Although there may be later improved versions, these data are ready for use in scientific publications. Each VI product contains 11 parameters, listed below:

1km 16 days NDVI
1km 16 days EVI
*1km 16 days NDVI Quality
*1km 16 days EVI Quality
1km 16 days red reflectance (MODIS Band # 1, 620 - 670 nm)
1km 16 days NIR reflectance (MODIS Band # 2, 841- 876 nm)
1km 16 days blue reflectance (MODIS Band # 3, 459 - 479 nm)
1km 16 days MIR reflectance (MODIS Band # 7, 2105- 2155 nm)
1km 16 days average view zenith angle (View zenith of the chosen pixel)
1km 16 days average sun zenith angle (Sun zenith of the chosen pixel)
1km 16 days average relative azimuth angle (Relative Azimuth of the chosen pixel)

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A.

Product	Resolution	Projection	Horizontal Datum	Vertical Datum
MODIS/Terra Vegetation Indices 16-Day L3 Global 1km SIN Grid	1 Kilometer	Lambert Azimuthal Equal Area Longitude_of_Projection_Center: -100 Latitude_of_Projection_Center: 45 False_Easting: 0 False_Northing: 0	None	Sphere

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A. ArcGrid is an Arc/Info proprietary format. Some other software packages can read the ArcGrid format. Customers who specify ArcGrid will be delivered a workspace. The workspace is not tarred or gzipped.

BIL is a non-proprietary format made by running the GRIDIMAGE command in Arc. The data is a simple binary raster format (signed integer data). There is an accompanying ASCII header file that provides file size information (number of rows and columns). The data are stored in row major order (all the data for row 1, followed by all the data for row 2, etc.).

GeoTIFF with world file .

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A. The coverage area is the conterminous US.

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A. More information concerning MODIS/Terra Vegetation Indices 16-Day L3 Global 1km SIN Grid can be found at
http://lpdaac2.usgs.gov/modis/mod13a2v4.asp

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