Why Do More Cyclones Occur in the Bay of Bengal than in the Arabian Sea?
Cyclones are intense tropical storms that form over warm ocean waters and can cause significant damage upon landfall. In the Indian Ocean region, it is observed that the Bay of Bengal experiences more frequent and intense cyclonic activity compared to the Arabian Sea. Several meteorological, geographical, and environmental factors contribute to this phenomenon. Let’s explore these factors in detail.
More cyclones occur in the Bay of Bengal than in the Arabian Sea due to several geographic and climatic factors:
- Geography and Topography: The Bay of Bengal is surrounded by land on three sides, creating a basin-like structure that traps and intensifies the moisture-laden air. This creates a conducive environment for cyclones to form and strengthen.
- Warmer Waters: The Bay of Bengal has warmer sea surface temperatures (around 28–30°C) compared to the Arabian Sea. Warmer water is a key factor in cyclone formation, as it provides the energy necessary to fuel cyclones.
- Moisture Availability: The Bay of Bengal receives more consistent inflow of warm, moist air from the Pacific and Indian Oceans, which enhances cyclone development. In contrast, the Arabian Sea has less inflow of moisture-laden winds, especially due to the influence of the dry, arid conditions of nearby regions like the Middle East.
- Monsoon Influence: The Bay of Bengal is more influenced by the south-west and north-east monsoon systems, which bring increased moisture, instability, and conducive wind patterns for cyclone formation.
- Topographical Barriers: The Western Ghats along the western coast of India act as a barrier, preventing the moist winds from moving into the Arabian Sea, thus reducing cyclone activity in that region.
Conclusion : While the Arabian Sea has seen an increase in cyclone activity in recent years due to climate change and warming sea surface temperatures, the Bay of Bengal remains the primary hotspot for cyclones in the Indian Ocean region.
FOR FURTHER DETAILED UNDERSTANDING:
More cyclones occur in the Bay of Bengal than in the Arabian Sea due to several geographic and climatic factors:
1. Geographical Features:
Enclosed Topography: The Bay of Bengal is more enclosed, bordered by landmasses on three sides, which helps in trapping heat and moisture.
Steering Winds: The shape of the bay aids in concentrating and directing winds, supporting the organization and intensification of cyclonic systems.
Land Interaction: The proximity to land influences the path and speed of cyclones, often causing them to linger and gain strength over the warm waters before making landfall.
2. Sea Surface Temperature (SST):
Warmer Waters: The Bay of Bengal generally has higher sea surface temperatures compared to the Arabian Sea. Warm waters are a crucial factor for cyclone formation as they provide the necessary energy and moisture.
Average SST: The Bay of Bengal maintains an average temperature of around 28-30°C, which is ideal for cyclone formation. In contrast, the Arabian Sea often has slightly lower temperatures, especially during certain seasons.
Heat Content: The deeper warm layers in the Bay of Bengal provide sustained energy, allowing cyclones to develop and intensify more effectively.
3. Moisture Availability
High Humidity Levels: The Bay of Bengal region has higher atmospheric moisture content, which fuels the growth and sustainability of cyclones.
Evaporation Rates: Abundant moisture from warm ocean waters leads to significant cloud formation and precipitation, essential components of tropical cyclones.
4. Atmospheric Conditions:
Southwest Monsoon: During the monsoon season, winds over the Bay of Bengal are conducive to cyclone formation. The transition periods before and after monsoons (pre-monsoon and post-monsoon seasons) are particularly favourable.
Wind Shear: The vertical wind shear (difference in wind speed and direction with height) over the Bay of Bengal is often moderate, which is suitable for cyclone development. In contrast, the Arabian Sea experiences higher wind shear, which can disrupt cyclone formation.
Intertropical Convergence Zone (ITCZ): The ITCZ tends to shift over the Bay of Bengal more prominently, providing the necessary convergence of winds and rising motion needed for cyclogenesis.
5. Salinity Levels:
Lower Salinity: The Bay of Bengal has lower salinity levels due to the influx of fresh water from numerous rivers like the Ganges, Brahmaputra, and Irrawaddy.
Effect on Evaporation: Lower salinity facilitates higher evaporation rates, contributing to increased moisture in the atmosphere, which is essential for cyclone development.
Stratification: The fresh water creates a layer over the saline water, maintaining higher surface temperatures and providing a conducive environment for cyclogenesis.
6. Historical and Climatological Patterns
Climatology: Historically, the Bay of Bengal has been a hotspot for cyclonic activity due to the consistent presence of favourable conditions.
Seasonal Variations: The post-monsoon season (October to December) sees a peak in cyclone occurrences in the Bay of Bengal, while the Arabian Sea remains relatively calmer.
Coriolis Effect: Being closer to the equator, both basins experience less Coriolis force, but the Bay of Bengal’s location allows for a slightly better environment for the necessary rotational effect to aid cyclone formation.
7. Influence of Surrounding Landmasses and Water Bodies
River Discharge: The massive discharge from rivers into the Bay of Bengal contributes to its unique thermal and salinity structure, promoting cyclogenesis.
Lack of Upwelling: Unlike the Arabian Sea, which experiences upwelling (bringing cooler water to the surface), the Bay of Bengal maintains consistently warm surface temperatures, essential for sustaining cyclones.
Conclusion: The higher frequency and intensity of cyclones in the Bay of Bengal compared to the Arabian Sea result from a complex interplay of warmer sea surface temperatures, lower salinity, favourable atmospheric conditions, and geographical features. Understanding these factors is crucial for improving cyclone prediction, preparedness, and mitigation strategies in the region.
Additional Note: In recent years, there has been an observed increase in cyclonic activity in the Arabian Sea, possibly linked to climate change and rising sea surface temperatures. Continuous monitoring and research are essential to understand and adapt to these changing patterns.
References:
India Meteorological Department (IMD)
National Oceanic and Atmospheric Administration (NOAA)
World Meteorological Organization (WMO)
Research articles on tropical cyclones and Indian Ocean climatology