GDO Standardized Precipitation Index CHIRPS, 12-month accumulation period (SPI-12) (version 1.0.0)

The 12-month Standardized Precipitation Index (SPI-12) is an indicator used to monitor meteorological drought based on precipitation anomalies over 12-month accumulation periods. SPI-12 serves as a proxy for medium-term impacts, such as reduced stream flow and reservoir storage, and for long-term impacts, such as reduced reservoir and groundwater recharge. The input data for calculating the SPI-12 is CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) rainfall estimates from rain gauge and satellite observations.