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ISLSCP Initiative II Home General Data Overview Vegetation Data Overview |
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ISLSCP Initiative II |
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Vegetation Data
The Global Inventory Modelling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) data sets were generated to provide a 22-year satellite record of monthly changes in terrestrial vegetation. New features of this dataset include reduced NDVI variations arising from calibration, view geometry, volcanic aerosols, and other effects not related to actual vegetation change. In particular, NOAA-9 descending node data from September 1994 to January 1995, volcanic stratospheric aerosol correction for 1982-1984 and 1991-1994, and improved NDVI using empirical mode decomposition/reconstruction (EMD) to minimize effects of orbital drift. Global NDVI was generated to provide inputs for computing the time series of biophysical parameters contained in the International Satellite Land Surface Climatology Project (ISLSCP) Initiative II collection. NDVI is used in climate models and biogeochemical models to calculate photosynthesis, the exchange of CO2 between the atmosphere and the land surface, land-surface evapotranspiration and the absorption and release of energy by the land surface.
Data Provider: Compton J. Tucker, Jorge Pinzon, Molly Brown, GIMMS/GSFC/NASA
 Data Files (ISLSCP II Disc #1) |
 Data Set Documentation |
 Image Viewing Tutorial |
The files can be decompressed using the PKZip program. Each file contains ASCII text. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. All values in these files are written as real numbers. Water bodies are assigned the value of -99, missing data over land are assigned the value of -88, and permanent ice is -77. The files at different spatial resolutions each contain the following numbers of columns and rows; 1 degree (1d), 360 columns by 180 rows: 1/2 degree (hd), 720 columns by 360 rows: 1/4 degree (qd), 1440 columns by 720 rows. Each file is named based on the month and year of the data.
Example: gimms_ndvi_1d_19900900.asc is the NDVI from September 1990.
The data are structured so that the upperleft corner of the first pixel is located at 90 North latitude and 180 West longitude.
Related Pages:
ISLSCP Initiative II Home
General Data Overview
Vegetation Data Overview
GIMMS NDVI Monthly
Revision Date: October 5, 2004