GDO Standardized Precipitation Index JRA-3Q, 1-month accumulation period (SPI-1) (version 1.0.0)

The 1-month Standardized Precipitation Index (SPI-1) is an indicator used to monitor meteorological drought based on precipitation anomalies over 1-month accumulation periods. SPI-1 serves as a proxy indicator for immediate impacts of droughts such as reduced soil moisture, snowpack, and flow in smaller creeks. The input data for calculating the SPI-1 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).