Antarctic oscillation

Winds associated with the Southern Annular Mode cause oceanic upwelling of warm circumpolar deep water along the Antarctic continental shelf,[5][6] which has been linked to ice shelf basal melt,[7] representing a possible wind-driven mechanism that could destabilize large portions of the Antarctic ice sheet.

[8] In its positive phase, the westerly wind belt that drives the Antarctic Circumpolar Current intensifies and contracts towards Antarctica.

[10] Its negative phase involves the belt moving towards the equator, whereby decreasing rainfall in the southeast of Australia in the summer and as well as raising the possibility of spring heatwaves.

Moreover, winters will usually be wetter than normal in the south and southwest with more snowfall in the alpine areas, but drier in the east coast due to less moist onshore flows from the east and blockage of cold fronts by the Great Dividing Range, which would act as a rain shadow.

[10] In 2014, Nerilie Abram used a network of temperature-sensitive ice core and tree growth records to reconstruct a 1000-year history of the Southern Annular Mode.

The Southern Annular Mode is usually defined as the difference in the zonal mean sea level pressure at 40°S ( mid-latitudes ) and 65°S (Antarctica). [ 1 ]
SAM from 1979 to 2020.
The westerly wind belt during its negative phase, as it expands towards southeastern Australia. [ 4 ]