GDO Standardized Precipitation Index JRA-3Q, 9-month accumulation period (SPI-9) (version 1.0.0)

The 9-month Standardized Precipitation Index (SPI-9) is an indicator used to monitor meteorological drought based on precipitation anomalies over 9-month accumulation periods. SPI-9 serves as a proxy indicator for medium-term impacts, such as reduced stream flow and reservoir storage. The input data for calculating the SPI-9 is JRA-3Q precipitation reanalysis (Japanese Reanalysis for Three Quarters of a Century, by Japan Meteorological Agency (JMA; https://jra.kishou.go.jp/JRA-3Q/index_en.html).