Central Idea

The Indian National Centre for Ocean Information Services (INCOIS), a division under the Ministry of Earth Sciences (MoES), has made a significant discovery regarding the Southern Annular Mode (SAM), a crucial climate pattern.
Their research has revealed that SAM plays a pivotal role in influencing sea conditions across the Indian Ocean.

What is Southern Annular Mode (SAM)?

	Description
Idea behind	Mode of atmospheric variability representing north-south movement of the westerly wind belt around Antarctica. Also known as Antarctic Oscillation (AAO).
Phases	Positive Phase: Wind belt contracts towards Antarctica. Negative Phase: Wind belt expands towards the equator.
Impact on Weather Patterns	Influences temperature, rainfall, and storm intensity in the Southern Hemisphere. Causes difference in the zonal mean sea level pressure at 40°S (mid-latitudes) and 65°S (Antarctica).
Influence on Indian Ocean	Affects ocean currents and sea surface temperatures, impacting regional weather and marine life.
Climate Change Connection	Trend towards more positive phases in recent decades, influenced by human-induced climate change.
Effect on Antarctic Ice	Impacts Antarctic ice sheets and sea ice extent through changes in wind patterns.
Global Climate Interaction	Interacts with other climate phenomena like ENSO.
Predictability and Variability	Exhibits seasonal predictability and interannual variability, important for long-term forecasting.
Marine Ecosystems	Affects marine ecosystems in the Southern Ocean, influencing productivity and species distribution.

Coastal Processes: Ocean surface waves are key players in shaping coastal processes, impacting shoreline erosion, sediment transport, coastal engineering, and recreational activities.
Scientific Approach: The scientific team leveraged 40 years of data (1979 to 2018) from the European Centre for Medium-Range Weather Forecast.

Positive SAM Phase: During a positive SAM phase, a cyclic pattern of warm sea surface temperature anomalies emerges, accompanied by strong winds that increase wave activity in the Indian Ocean. A new swell generation region along the east African coast contributes to heightened wave heights in the Arabian Sea.
Negative SAM Phase: Conversely, during a negative SAM phase, the eastern tropical southern Indian Ocean becomes the primary region for generating swells, resulting in reduced wave heights in the Arabian Sea.

Coastal Planning: Understanding SAM allows for better coastal planning, helping coastal communities prepare for the impact of changing sea conditions.
Resource Management: SAM insights can aid in more efficient resource management, optimizing the utilization of marine resources.
Disaster Preparedness: Knowledge of SAM patterns can enhance disaster preparedness efforts, enabling timely response to potential ocean-related disasters.
Wave Predictions: The research contributes to improving wave predictions, offering advanced forecasting capabilities.
Benefiting Stakeholders: Stakeholders in the blue economy, including shipping, maritime boards, and the oil industry, can optimize their multi-million-dollar operations at sea based on SAM insights.

Monsoon Season Impact: Typically, inland vessel operations and oil exploration activities face restrictions during the monsoon season.
Fair Sea State Windows: Predicting SAM phases through the Ocean Forecasting System can identify “Fair Sea state windows” during monsoons.
Impact on Blue Economy: These fair windows can be leveraged by oil and shipping industries, making a significant contribution to blue economy activities along the Indian coast