Global Data Archive 2: AVHRR NDVI 1981 - 2000

The Global Data Archive 2 contains monthly NDVI (Normalized Difference Vegetation Index) maximum value composite images (July, 1981-2000, with the exception of September-December 1994), average and standard deviation of monthly NDVI for the twelve months, and ancillary data (land cover and country boundaries and coastline) for the world in IDRISI format. The archive size is 2 GB. The download size is 360 MB.

All files are provided in the latitude / longitude reference system.

Monthly NDVI Maximum Value Composite

0.1 degree resolution monthly NDVI maximum value composite images were originally downloaded from the NASA Goddard DAAC ftp site:  http://glcf.umiacs.umd.edu/data/gimms/

The original data set was produced as part of the NOAA/NASA Pathfinder AVHRR Land Program. Its production and distribution were funded by NASA's Mission to Planet Earth Program. The data were re-projected from Goode Interrupted Homolosine Projection to Geographic Projection in IDRISI (stored in byte format, 0 is missing data over land, 1 is ocean, 2 is Goode's interrupted space).

Mean and Standard Deviation of NDVI

Average NDVI for each image pixel over an 18-year period (excluding 1981 and 1994 data from calculation) was computed for each month, resulting in 12 mean NDVI images for January through December. The standard deviation of NDVI in the same month of each year at each pixel was computed as well to create January through December standard deviation images. The average images are stored in byte format while the standard deviation images are in real format.

Land Cover Data

Global land cover data was originally downloaded from the USGS EROS Data Center DAAC-GLCC  Global Land Cover Characteristics Data Base site. The USGS Land Use/Land Cover Scheme was created from 1992-93 AVHRR-NDVI.  The Land Use/Land Cover image is in byte format.

Vector Boundary Files

The global nation vector boundary file was obtained from: http://www.gisdatadepot.com/editorspicks/data_world11.html
The file was contributed to the Free GIS Data Community by: Nick Nazarenko, GIS Developer, Russian Center for Applied Geoinformatics. 

The spatial resolution for the NDVI images is 0.1 degree. Each image has 3600 columns and 1800 rows.

The resolution of the Land Use/Land Cover images is approximately 1 km, or 0.0083332 degrees. 

To facilitate image analysis between the Land Use/Land Cover image and the 0.1 degree resolution NDVI images, the 1 km image has been resampled to a 3600 x 1800 image with matching coordinates.  The original data has been preserved in continental segments as described below.