Investigating the role of the Madden-Julian Oscillation in Antarctic sea ice variability

In the tropics, deep convection triggers upper-level quasi-stationary Rossby waves that propagate to higher latitudes and influence local climate patterns. This study examines the teleconnection between the Madden-Julian Oscillation (MJO), the dominant mode of tropical intraseasonal variability, and Antarctica, using daily gridded observational datasets (precipitation from CMAP, 250-hPa geopotential height, 2 m air temperature, and 10 m winds from ERA5, and sea ice concentration from NSIDC) and the Linear Response Theory Method (LRTM) across all southern seasons during 1979-2014. Our results reveal that MJO-driven variations in surface temperature and winds substantially affect Antarctic sea ice concentration throughout the year. In austral summer and autumn, significant sea ice responses are evident in both the eastern (Lazarev Sea to Somov Sea) and western Antarctic sectors (Ross Sea, Amundsen Sea, and Weddell Sea). During summer, the most notable sea ice changes occur in MJO phases 1 and 5, while in autumn, the most potent responses are associated with phases 1–3. Conversely, in winter and spring, the sea ice responses are primarily restricted to the western Antarctic sectors (Ross Sea, Amundsen Sea, Bellingshausen Sea, and Weddell Sea). All MJO phases exert a pronounced influence on sea ice in winter, whereas in spring, phases 1 and 5 dominate. The LRTM effectively elucidates the mechanisms underlying these changes, attributing the observed sea ice variability to wind-driven forcing, thermal advection, or their combined effects.