Global Monthly Vegetation Cover

NDVI (8-bit) Data Format Description

Introduction Page, Digital Data Information

The digital NDVI data are arranged in a 2500 x 904 longitude/latitude array (Plate Carrée projection). The first map cell is located at the northwest corner of the geographic domain (75N -55S, 180W - 180E). All values are scaled to 8-bit precision and can be converted to floating point values using the following equation for NDVI:

where I = 0 to 255. Note: the count 255 represents a real, physical value.

There are 904 records in each data file, with each record being 2500 bytes in length.

The green vegetation fraction, f_g, can be derived from NDVI using a simple linear relationship with an assumption of dense vegetation (high leaf area index) (Gutman and Ignatov 1997):

where NDVI_min=0.04 and NDVI_max=0.52 can be prescribed as global constants (Gutman and Ignatov 1997) as a first approximation. The values of f_g should be restricted to be between 0 and 1. The conversion to f_g is merely a rescaling of NDVI for a more convenient analysis, but is not absolutely necessary.

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