Tripole-like Antarctic sea ice pattern linked to remote forcing from the Indian Ocean and Maritime Continent

Antarctic sea ice variability has long been characterized by a dipole pattern primarily located in West Antarctica, attributed to the Amundsen Sea Low and remote forcing from the tropical Pacific, while variability in other sectors has received less attention. Here we reveal a tripole-like pattern of sea ice variability spanning multiple sectors of Antarctica, comprising the classic dipole together with seasonally varying centers in East Antarctica during austral winter and spring. Using observational analyses and numerical experiments, we demonstrate that, unlike the dipole, this tripole is not governed solely by the Amundsen Sea Low. Instead, it emerges from paired atmospheric circulation anomalies that impose coherent wind forcing along the sea ice edge, initiated by Rossby wave trains from the Pacific, Indian Ocean and Maritime Continent. These findings provide a broader framework for Antarctic sea ice variability and highlight previously overlooked Indian Ocean-Maritime Continent drivers of Antarctic climate predictability. Antarctic sea-ice variability follows a seasonally shifting tripole pattern, which extends beyond the traditional dipole pattern and highlights key forcing from Indian Ocean-Maritime Continent Rossby wave trains, according to observation-based analyses and numerical experiments.