About Southern Annular Mode:
- It is the north-south movement of Southern Westerly Winds over timescales of 10s to 100s of years.
- It is also known as the Antarctic Oscillation.
- They blow almost continuously in the mid- to high-latitudes of the southern hemisphere.
- It is usually defined as the difference in the zonal mean sea level pressure at 40°S (mid-latitudes) and 65°S (Antarctica).
- Positive Southern Annular Mode
- In this mode, there is lower anomalous air pressure over Antarctica and higher anomalous air pressure over the mid-latitudes.
- The belt of strong westerly winds strengthens and contracts towards Antarctica.
- Negative Southern Annular Mode
- In this mode, the belt of strong Southern Westerly Winds expands northwards towards the equator, bringing cold, wet weather to Patagonia, glacier advance, and decreased Circumpolar Deep Water upwelling on the Antarctic Continental Shelf.
- Significance
- The study contributes to advancing the accuracy of wave predictions and can help identify fair-weather windows.
- It will benefit the fishing community and blue economy stakeholders such as shipping, maritime boards and the oil industry for their multi-million dollar operations at sea.
