South Pacific ocean–atmosphere coupling sustains El Niño-Southern Oscillation’s remote influence on Antarctic

El Niño-Southern Oscillation events are major climate anomalies originating in the tropical Pacific. While known to affect remote regions during their active phases (December, January, February), this study shows their influence on Antarctic sea ice can persist into the following austral winter (June, July, and August), long after El Niño-Southern Oscillation itself has faded. El Niño-Southern Oscillation-triggered sea surface temperature anomalies in the South Pacific persist for months due to oceanic heat capacity. Through a combined analysis of open-access observational data and climate model experiments, we find these lingering sea surface temperature anomalies affect the atmospheric circulation by altering diabatic heating and transient eddy activities. This subsequently impacts Antarctica, creating a persistent sea ice dipole anomaly—more ice near the Antarctic Peninsula and less in the Amundsen Sea after an El Niño event. These delayed effects are driven by South Pacific ocean-atmosphere interactions, an insight crucial for improving Antarctic climate predictions. South Pacific ocean-atmosphere coupling allows the influence of El Niño-Southern Oscillation on Antarctic sea ice to persist into the following austral winter, creating a long-lasting sea ice dipole, according to a combined analysis of observational data and climate models