Sea surface temperature anomalies related to the Antarctic sea ice extent variability in the past four decades

Abstract

The Antarctic sea ice extent, though varying considerably with season and region, had been on a slight increasing trend from late 1970s until mid-2010s when the trend was suddenly reversed. The sea surface temperature anomalies related to the multi-decadal expansion and recent contraction in the Antarctic sea ice extent remain to be uncovered. Here, we demonstrate that the variations in the Antarctic sea ice extent from 1979 through 2020, including the abrupt change in direction that occurred in mid-2010’s, can be explained at least partially by the sea surface temperature (SST) oscillations in the Pacific and Atlantic Oceans. Specifically, we show that the changes in the Antarctic sea ice extent are significantly correlated with the Interdecadal Pacific Oscillation (IPO) in all seasons and to the Atlantic Multidecadal Oscillation (AMO) in austral winter and spring. We further demonstrate that SST anomalies trigger planetary wavetrains of different magnitudes and propagating paths depending on seasons. These planetary wavetrains induce anomalous atmospheric circulations over the Southern Ocean that, through transport and melting/freezing, ultimately change sea ice extent.