The Southern Annular Mode, also called the Antarctic Oscillation, is the dominant pattern of atmospheric variability in the extratropical Southern Hemisphere: a north-south shift of the belt of westerly winds that circles Antarctica, alternating between a positive phase, in which the belt contracts poleward and strengthens, and a negative phase, in which it expands toward the equator. Its positive phase has trended stronger in recent decades, linked to stratospheric ozone depletion and rising greenhouse gases, with measurable effects on Southern Hemisphere rainfall, ocean circulation and the extent of Antarctic sea ice. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
Facts
Timescale
Timescale (category) Timescale (category) Process Type TimescaleIndividual phase swings occur over days to weeks, riding on top of a multi-decadal trend. 1 Connections
Associated With
Source Southern Annular Mode (Wikipedia)
Demonstrated By
Sources
1. Southern Annular Mode (Wikipedia)
Wikimedia FoundationLead section
The Antarctic oscillation (AAO, to distinguish it from the Arctic oscillation or AO), also known as the Southern Annular Mode (SAM), is a low-frequency mode of atmospheric variability of the Southern Hemisphere that is defined as a belt of strong westerly winds or low pressure surrounding Antarctica which moves north or south as its mode of variability.
- In Category: Physical Processes
- Associated With: Polar Cell Circulation
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