Antarctic oscillation

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The Antarctic oscillation (AAO, to distinguish it from the Arctic oscillation or AO) is a low-frequency mode of atmospheric variability of the southern hemisphere. It is also known as the Southern Annular Mode (SAM) or Southern Hemisphere Annular Mode (SHAM). It is defined as a belt of westerly winds or low pressure surrounding Antarctica which moves north or south as its mode of variability.[1] In its positive phase, the westerly wind belt contracts towards Antarctica, while its negative phase involves this belt moving towards the Equator.

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  1. ^ Australian Bureau of Meteorology - The Southern Annular Mode. Accessed 25/10/2013.

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