Antarctic Oscillation (AAO)
What is Antarctic Oscillation (AAO) ?
When is the most active season of AAO variability ? How do scientists monitor and predict AAO index ? How is the tropospheric AAO related to the polar vortex variability in the stratosphere ?
What is Antarctic Oscillation (AAO) ?The Antarctic Oscillation (AAO), also known as Southern Annular Mode (SAM), is the most dominant mode of atmospheric variability in the Southern Hemisphere. An atmospheric circulation pattern associated with AAO is characterized as a meridional movement of momentum and mass across the midlatitude (about 45°S) on time scales ranging from weeks to decades, which exhibits zonally symmetric and vertically equivalent barotropic structure (loading pattern of AAO ).
When AAO index is positive (negative height anomaly over the polar area, i.e., stronger polar vortex), the upper trospheric jet stream and storm tracks tend to move poleward and vice versa when AAO index is negative (positive height anomaly over the polar area, i.e., weaker polar vortex).
When is the most active season of AAO variability ?The variability of AAO is largest during warm season (May-September) (Variance of AAO). The seasonality of AAO is less distinct than that of AO, which is the counterpart of AAO in the Northern Hemisphere.
How do scientists monitor and predict AAO index ?
How is the tropospheric AAO related to the polar vortex variability in the stratosphere ?AO...