Seasonal teleconnections between SPI-6 and Ocean–Atmosphere variability for drought prediction in Korea

We examined seasonal teleconnections between the six-month Standardized Precipitation Index (SPI-6) over Korea and large-scale ocean–atmosphere variability for 1991–2020, in order to identify climate indices useful for mid- to long-term drought monitoring. Korea-averaged monthly SPI-6 from the Korea Meteorological Administration was related to global sea-level pressure, sea-surface temperature fields, and 21 standard climate indices using correlation, composite anomaly, and Random Forest analyses. Results reveal distinct seasonal teleconnection patterns: spring anticyclones from Siberia to the North Pacific with La Niña–like central Pacific SSTs, summer cyclonic anomalies over the North Pacific that weaken the North Pacific High and moisture transport to Korea, autumn anticyclones over Siberia and the North Pacific with warm SSTs in the central–eastern Pacific, and winter weakening of the Aleutian Low. Correlations with climate indices and RF-based variable importance together indicate that a set of 12 ENSO-related and extratropical indices provide the strongest and most robust links to SPI-6, and thus represent promising candidates for drought monitoring in Korea.