Introduction Page, GVI Sample Imagery

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Plate Carrée Projection of Third Generation B-Level (weekly) Precipitable Water Index (PWI) data from February, May, August and November 1996. PWI is calculated from the difference of the two AVHRR brightness temperatures (Channel 4 minus Channel 5). PWI gives some indication of the actual water vapor amount over land, although there are some limitations. The images of the Third Generation PWI are in color, where the dark purple indicates an abundance of water vapor or moisture in the atmosphere, the yellow/light green areas indicate moderate water vapor, and the dark brown indicates a very dry atmosphere. The images in this series closely correspond to the Third Generation B-Level NDVI data, in the respect that the areas with the most vegetation generally correlate to the areas with the highest PWI.

FEBRUARY	MAY
AUGUST	NOVEMBER