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Soil Moisture Anomaly (SMA)

Agricultural drought events can affect large regions across the world. Soil moisture (or soil water content) is an important variable for plant growth, and - together with precipitation and evapotranspiration - is a basic component of the hydrological cycle. The Soil Moisture Anomaly (SMA) indicator is used to detect and monitor agricultural drought, that is when there is reduced crop production due to insufficient soil moisture. It is computed as a deviation from the climatological reference period, and is updated 3 times a month (after the 10th, the 20th and the last day of the month). This layer displays the map for the last full decade of the current month. Negative anomalies (shades of brown) represent dry conditions.

Cammalleri, C., Vogt, J.V., Bisselink, B. and A. de Roo. 2017. Comparing soil moisture anomalies from multiple independent sources over different regions across the globe. Hydrol. Earth Syst. Sci. 21, 6329-6343.

Last full 10-day period

The maps of soil moisture anomalies can be used as a “proxy” for the presence of potential drought conditions. Of course, the presence of actual water stress conditions will also depend on the specific plants’ resistance and capacity for water extraction from the soil matrix. The Triple Collection method (combination of three base products) provides accurate estimates of the weighting factors only under very strict hypotheses.

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