File Name Convention
--------------------
The files in this data set are named using the following naming convention:

                       gimms_ndvi_xx_YYYYmm00.asc

where

gimms_ndvi         identifies the data set.
xx                 identifies the spatial resolution of the data set where 1d,
                   hd, and qd stand for a spatial resolution of 1, 1/2 and 1/4 
                   degrees in both latitude and longitude, respectively.
YYYY               is the four-digit year from 1981 to 2002.
mm00               is the two-digit month from 01 to 12, and "00" means it is
                   a monthly average.

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ASCII File Format
------------------
All of the files in the ISLSCP Initiative II data collection are in the ASCII, 
or text format. 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 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:
    One degree: 360 columns by 180 rows 
    1/2 degree: 720 columns by 360 rows 
    1/4 degree: 1440 columns by 720 rows 

All files are gridded to a common equal-angle lat/long grid, where the 
coordinates of the upper left corner of the files are located at 180 degrees
W, 90 degrees N, and the lower right corner coordinates are located at 180
degrees E, 90 degrees S. Data in the files are ordered from North to South and
from West to East beginning at 180 degrees West and 90 degrees North.