The Uniqueness of the North Indian Ocean

• The north Indian Ocean experiences two cyclone seasons: pre-monsoon and post-monsoon.
• This region contributes significantly to the summer monsoon by providing moisture through evaporation.
• Despite its warm seas, the north Indian Ocean is the least active cyclone region globally.
• A combination of factors favors and suppresses cyclogenesis, creating unusual cyclone seasons.

Why is the Indian Ocean Unique?

• Monsoonal wind reversals and ‘oceanic tunnels’ connecting the Pacific and Southern Oceans make the Indian Ocean unique.
• Warm water inflows from the Pacific and cooler waters from the Southern Ocean affect cyclone formation.
• The Bay of Bengal is warmer and more prone to cyclones than the Arabian Sea due to higher convective activity.

Role of Climate Change

• Climate change is amplifying warming in the Indian Ocean through increased heat from the Pacific and Southern Oceans.
• Warming impacts ocean heat uptake and monsoonal systems, altering cyclogenesis.
• The Indian Ocean acts as a clearinghouse for ocean warming, affecting cyclone numbers and intensity.

Cyclone Activity in the Arabian Sea

• The Arabian Sea cools significantly during monsoon seasons due to strong wind activity.
• Vertical wind shear during the monsoon suppresses cyclone formation despite warm waters.
• The Arabian Sea has fewer cyclones than the Bay of Bengal, with stronger wind shear and less convective activity.

The Rare August Cyclone: Asna

• Asna, the first August cyclone in the north Indian Ocean since 1981, formed from a strong land-born depression.
• The depression fed off prior rainfall, intensified over land, and gained energy from the warm Arabian Sea.
• The cyclone caused significant damage and fatalities before dissipating due to dry desert air.

Conclusion

• The Arabian Sea’s unique climatic and oceanic conditions make cyclones rare.
• Climate change and warming oceans are leading to unusual cyclonic patterns.
• Surprises like Cyclone Asna demonstrate the unpredictable nature of cyclone formation in this region.