Earth Observation
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.   More
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. The crop mask is FAO GLC-SHARE.
DISCLAIMERS
The boundaries and names shown and the designations used on the maps do not imply the expression of any opinion whatsoever on the part of FAO concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers and boundaries.
 
YearDekad
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Agricultural Stress Index  More
The Agricultural Stress Index (ASI) is a quick-look indicator that facilitates the early identification of cropped land with a high likelihood of water stress (drought). The Index is based on the integration of the Vegetation Health Index (VHI) in two dimensions that are critical in the assessment of a drought event in agriculture: temporal and spatial. The first step of the ASI calculation is a temporal averaging of the VHI, assessing the intensity and duration of dry periods occurring during the crop cycle at the pixel level; this calculation includes the use of crop coefficients, which introduces sensitivity of a crop to water stress during each phenological phase. The second step determines the spatial extent of drought events by calculating the percentage of pixels in arable areas with a VHI value below 35 percent (this value was identified as a critical threshold in assessing the extent of drought in previous research by Kogan, 1995). Each administrative area is classified according to the percentage of the affected area to facilitate the quick interpretation of results.



Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of the drought is calculated through the Weighted Mean Vegetation Health Index aggregated per GAUL 2 region, indicating that the poorer the vegetation health the more severe the drought.



Progress of Season  More
The indicator depicts the development of crops/pastures during the growing season. For any dekad (a 10-day period), the map indicates how far the season has progressed, represented by a value between 0 and 100 percent (i.e. 50 percent is the mid-point of the growing season). The seasons’ progress is based on the long-term average of vegetation phenology for each pixel. This simplification implies that the crop/pasture phenology is static and, therefore, the growing seasons progress at a constant rate each year.



Mean Vegetation Health Index  More
The Mean Vegetation Health Index (Mean VHI) allows the user to assess the severity of the drought from the start of the growing season, examining the vegetation health and the influence of temperature on plant conditions. The Mean VHI is an average of the dekadal VHI values over the crop-growing season to date. It takes into account the sensitivity of a crop to water stress over its growing season and calculates the temporal impact of moisture deficits since the start of the growing season until the current dekad.


 
YearDekad
Select:                        

Agricultural Stress Index  More
The Agricultural Stress Index (ASI) is a quick-look indicator that facilitates the early identification of cropped land with a high likelihood of water stress (drought). The Index is based on the integration of the Vegetation Health Index (VHI) in two dimensions that are critical in the assessment of a drought event in agriculture: temporal and spatial. The first step of the ASI calculation is a temporal averaging of the VHI, assessing the intensity and duration of dry periods occurring during the crop cycle at the pixel level; this calculation includes the use of crop coefficients, which introduces sensitivity of a crop to water stress during each phenological phase. The second step determines the spatial extent of drought events by calculating the percentage of pixels in arable areas with a VHI value below 35 percent (this value was identified as a critical threshold in assessing the extent of drought in previous research by Kogan, 1995). Each administrative area is classified according to the percentage of the affected area to facilitate the quick interpretation of results.



Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of the drought is calculated through the Weighted Mean Vegetation Health Index aggregated per GAUL 2 region, indicating that the poorer the vegetation health the more severe the drought.



Progress of Season  More
The indicator depicts the development of crops/pastures during the growing season. For any dekad (a 10-day period), the map indicates how far the season has progressed, represented by a value between 0 and 100 percent (i.e. 50 percent is the mid-point of the growing season). The seasons’ progress is based on the long-term average of vegetation phenology for each pixel. This simplification implies that the crop/pasture phenology is static and, therefore, the growing seasons progress at a constant rate each year.



Mean Vegetation Health Index  More
The Mean Vegetation Health Index (Mean VHI) allows the user to assess the severity of the drought from the start of the growing season, examining the vegetation health and the influence of temperature on plant conditions. The Mean VHI is an average of the dekadal VHI values over the crop-growing season to date. It takes into account the sensitivity of a crop to water stress over its growing season and calculates the temporal impact of moisture deficits since the start of the growing season until the current dekad.


Year
Select:         

Agricultural Stress Index   More
The Annual ASI depicts the percentage of arable land, within an administrative area, that has been affected by drought conditions over the entire cropping season. It differs from ASI, which is based on conditions from the start of the season up to the current dekad.
 



Drought Intensity   More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of drought is calculated through the Weighted Mean Vegetation Health Index, indicating that the poorer the vegetation health the more severe the drought. The Annual summary of Drought Intensity allows the user to assess the overall intensity of drought for an entire growing season.
 



Mean Vegetation Health Index   More
The Annual Mean Vegetation Health Index (Mean VHI) allows the user to assess the overall severity of drought for an entire growing season, examining the vegetation health and the influence of temperature on plant conditions. The Annual Mean VHI takes into account the sensitivity of a crop to water stress over its growing season, and calculates the temporal impact of moisture deficits and temperature over the complete growing season.
 

Year
Select:         

Agricultural Stress Index   More
The Annual ASI depicts the percentage of arable land, within an administrative area, that has been affected by drought conditions over the entire cropping season. It differs from ASI, which is based on conditions from the start of the season up to the current dekad.
 



Drought Intensity   More
The Annual ASI depicts the percentage of arable land, within an administrative area, that has been affected by drought conditions over the entire cropping season. It differs from ASI, which is based on conditions from the start of the season up to the current dekad.
 



Mean Vegetation Health Index   More
The Mean Vegetation Health Index (Mean VHI) allows the user to assess the severity of the drought from the start of the growing season, examining the vegetation health and the influence of temperature on plant conditions. The Mean VHI is an average of the dekadal VHI values over the crop-growing season to date. It takes into account the sensitivity of a crop to water stress over its growing season and calculates the temporal impact of moisture deficits since the start of the growing season until the current dekad.
 

The seasons’ progress is based on the long-term average of vegetation phenology for each pixel. This simplification implies that the crop/pasture phenology is static and therefore the growing seasons progress at a constant rate each year.
Start of Season (SOS) indicates the period of a crop/grass’s emergence, and is defined as the point when the NDVI reaches 25 percent of its maximum value.


Maximum of Season (MOS) indicates the period when the crop/grass’s foliage is fully developed, prior to the harvest period. It is calculated as the point when the NDVI is at its maximum value.


End of Season (EOS) indicates when the crop/grass has reached full maturity, and is defined as the point when the NDVI is at 75 percent for crop and 25 percent for grass of its maximum value (MOS).


The seasons’ progress is based on the long-term average of vegetation phenology for each pixel. This simplification implies that the crop/pasture phenology is static and therefore the growing seasons progress at a constant rate each year.
Start of Season (SOS) indicates the period of a crop/grass’s emergence, and is defined as the point when the NDVI reaches 25 percent of its maximum value.


Maximum of Season (MOS) indicates the period when the crop/grass’s foliage is fully developed, prior to the harvest period. It is calculated as the point when the NDVI is at its maximum value.1


End of Season (EOS) indicates when the crop/grass has reached full maturity, and is defined as the point when the NDVI is at 75 percent for crop and 25 percent for grass of its maximum value (MOS).1



Historic Drought Frequency   More
The maps depict the frequency of severe drought in areas where: i) 30 percent of the cropped land; or ii) 50 percent of the cropped land has been affected. The historical frequency of severe droughts (as defined by ASI) is based on the entire the times series (1984-2017).
>30% of the cropland affected  
 


>50% of the cropland affected



Historic Drought Frequency   More
The maps depict the frequency of severe drought in areas where: i) 30 percent of the cropped land; or ii) 50 percent of the cropped land has been affected. The historical frequency of severe droughts (as defined by ASI) is based on the entire the times series (1984-2017).
>30% of the cropland affected