Impact of the Madden-Julian oscillation on Antarctic sea ice and its dynamical mechanism

Abstract

The influence of the Madden-Julian oscillation (MJO) on Antarctic sea ice extent has not been extensively explored. This study investigates intraseasonal variability of the sea ice extent induced by the MJO and its physical mechanism. During austral winter, the sea ice extent anomaly exhibits considerable melting and freezing as the MJO evolves. Numerical experiments and the Rossby wave theory show that the high-latitude circulation anomalies in response to the MJO are responsible for the sea ice change. The MJO-induced Rossby waves propagate into the Southern Hemisphere through the northerly ducts over the western Indian Ocean–central Africa and the Maritime Continent. The MJO-induced circulation anomalies reach high latitudes and lead to anomalous meridional temperature advection, causing changes in the sea ice extent. The time difference between the meridional wind and sea ice anomalies is ~5 days. As the MJO moves, the sea ice extent anomaly also exhibits eastward-migrating behavior. Strong sea ice melting in the total anomaly is synchronous to the evolution of the MJO, suggesting the practical usefulness of the location of the MJO for the prediction of the sea ice decrease.