The Impact of the Indian Ocean Basin Mode on Antarctic Sea Ice Concentration in Interannual Time Scales.

The Antarctic sea ice variability has been linked to tropical sea surface temperature. However, little is known as to whether and how the Indian Ocean Basin Mode (IOBM) influences Antarctic sea ice changes. We revealed the existence of a teleconnection between the IOMB and Antarctic sea ice anomalies, which is much stronger in austral spring and autumn than summer and winter. In particular, under the positive phase of the IOBM, significant positive sea ice anomalies occur in the Bellingshausen and northern Weddell Seas, in contrast to negative anomalies in the Amundsen Sea, the southern Atlantic Ocean, and the coastal seas off Dronning Maud Land. This teleconnection is established by planetary wavetrains excited over the tropical Indian Ocean and the tropical Pacific Ocean and is modulated by El Niño‐Southern Oscillation. The IOBM‐related Antarctic sea ice anomalies are largely consistent with those of the anomalous surface air temperature and wind fields associated with the IOBM. Plain Language Summary: The variability of sea surface temperature in the tropical Indian Ocean is dominated by two modes, the Indian Ocean Dipole (IOD) and the Indian Ocean Basin Mode (IOBM). While previous studies have linked IOD to Antarctic sea ice changes, little is known about whether and how IOBM may affect seasonal Antarctic sea ice. Using 40‐year (1979–2018) observational and reanalysis data, we found that there exists a significant teleconnection between the IOBM and the Antarctic sea ice anomalies in austral autumn and spring, and that this remote connection can be largely explained by anomalous atmospheric circulations. Key Points: A teleconnection exists between the Antarctic sea ice anomalies and the sea‐surface‐temperature anomaly known as the Indian Ocean Basin Mode (IOBM)The IOBM and Antarctic sea ice connection varies spatially and seasonally, is stronger in autumn and spring, and is modulated by El Niño‐Southern Oscillation (ENSO)Removing the ENSO modulation, the extent of sea ice concentration anomalies shrinks a lot, and the source of the wavetrain moves westward [ABSTRACT FROM AUTHOR]