Global Information and Early Warning System on Food and Agriculture (GIEWS) monitors the condition of major foodcrops across the globe to assess production prospects. To support the analysis and supplement ground-based information, GIEWS utilizes remote sensing data that can provide a valuable insight on water availability and vegetation health during the cropping seasons. In addition to rainfall estimates and the Normalized Difference Vegetation Index (NDVI), GIEWS and FAO's OCB Division have developed the Agricultural Stress Index (ASI), a quick-look indicator for the early identification of agricultural areas probably affected by dry spells, or drought in extreme cases.
