Context:
Recently, the Indian National Centre for Ocean Information Services (INCOIS) discovered that the Southern Annular Mode (SAM), an important climate pattern, plays a pivotal role in shaping sea conditions across the Indian Ocean.
Relevance:
GS I: Geography
Dimensions of the Article:
- Southern Annular Mode (SAM): Understanding Antarctic Oscillation
- Significance
Southern Annular Mode (SAM): Understanding Antarctic Oscillation
- Definition: The Southern Annular Mode (SAM) refers to the north-south movement of Southern Westerly Winds occurring over timescales of 10s to 100s of years.
- Other Name: Also known as the Antarctic Oscillation.
- Geographical Range: These winds persistently blow in the mid- to high-latitudes of the southern hemisphere.
Characteristics:
- Definition Basis: SAM is typically defined as the difference in the zonal mean sea level pressure at 40°S (mid-latitudes) and 65°S (Antarctica).
SAM Modes:
Positive SAM:
- Lower anomalous air pressure over Antarctica.
- Higher anomalous air pressure over the mid-latitudes.
- Strengthens and contracts the belt of strong westerly winds towards Antarctica.
Negative SAM:
- Belt of strong Southern Westerly Winds expands northwards towards the equator.
- Results in cold, wet weather in Patagonia, glacier advance, and decreased Circumpolar Deep Water upwelling on the Antarctic Continental Shelf.
Significance:
- Wave Predictions: Advances in SAM understanding contribute to more accurate wave predictions, aiding in identifying fair-weather windows.
- Beneficiaries: Fishing communities, as well as stakeholders in the blue economy like shipping, maritime boards, and the oil industry, stand to benefit from improved operations at sea.
-Source: The Hindu
