Abstract: Using NCEP-DOE reanalysis datasets, sea ice concentration data from the Hadley Center and sunspot number data, we investigated possible linkages between Antarctic sea ice and the 11-year solar cycle as well as related physical processes. In years with high solar activity, sea ice concentration is low in the vicinity of the Ross Sea and high in the Weddell Sea near the Antarctic Peninsula. We introduced a sea ice dipole (SID) index, and found that Antarctic SID is significantly negatively correlated with the Antarctic Oscillation (AAO), possibly through the mediation of the westerly jet. When the AAO is strong, the westerly stream turns southward around the Antarctic Peninsula–Weddell Sea, and northward near the Ross Sea, resulting in negative SID anomalies as warm air enters the Antarctic Peninsula–Weddell Sea region and cold air intrudes over the Ross Sea. Sea ice and circulation anomalies are reversed when the AAO is weak. This indicates that solar activity and Antarctic sea ice variability may be linked through the effects of solar activity on AAO, which may originate from temperature responses in the stratosphere. As a result of changes in meridional circulation, redistribution of air masses in the atmosphere tends to induce negative AAO in the lower troposphere during years with high solar activity.

Key words: solar activity, Antarctic sea ice, Antarctic Oscillation