Agricultural Stress Index System (ASIS)-FAO Global Agricultural Drought Monitoring System
Agricultural Stress Index System (ASIS) is a global agricultural drought monitoring system developed and operated by FAO which enables to monitor agricultural areas affected by dry spells, or severe drought in extreme cases, using satellite data. It provides a collective quick-look indicators that facilitate the early identification of cropland/grassland with a high likelihood of water stress (drought).
Agricultural Stress Index System is composed of two type of indicators: seasonal indicators such as Agricultural Stress Index (ASI) to detect the severe agricultural drought, Drought Intensity to classify the severity of the drought and no-seasonal indicators, such as vegetation indicators (NDVI anomaly, Vegetation Condition Index and Vegetation Health Index).
The seasonal indicators are designed to allow easy identification of areas of cropped land with a high likelihood of water stress (drought). The indices are based on remote sensing data of vegetation and land surface temperature combined with information on agricultural cropping cycles derived from historical data and a global crop mask. The final maps highlight anomalous vegetation growth and potential drought in crop zones during the growing season.
In ASIS, two cropping cycles (season 1/season 2) and crop/grassland zones are applied.
The satellite data used in the calculation of the mean VHI and the ASI is the 10-day (dekadal) vegetation data from the METOP-AVHRR sensor at 1 km resolution (2007 and after). Data at 1 km resolution for the period 1984-2006 was derived from the NOAA-AVHRR dataset at 16 km resolution.