Why in the News?

A rare August cyclone, named ‘Asna’, currently positioned off the Kutch coast is even more remarkable for having originated over land.

Why was there a lot of excitement over Asna?

“Asna” is notable because it’s the first cyclone in August in the North Indian Ocean since 1981. August is typically not part of the cyclone season in this region.
The cyclone began as a land-born depression that intensified as it moved over the warm waters of the Arabian Sea. It formed from a rare strong low-pressure system that grew unusually powerful over land.
Asna’s formation is linked to the broader context of rapid warming over the Arabian Sea, influenced by climate change. The northward shift of the low-level jet stream due to warming over West Asia contributed to its development.

The North Indian Ocean has two distinct cyclone seasons due to the unique monsoonal circulation patterns in the region:

Pre-monsoon season (March-May): The Arabian Sea warms rapidly during this time as the sun crosses over to the Northern Hemisphere. The Bay of Bengal is relatively warmer and begins producing atmospheric convection and rainfall. This leads to cyclogenesis in both the Arabian Sea and the Bay of Bengal.
Post-monsoon season (October-December): This is the northeast monsoon season for India. The Arabian Sea cools due to the strong southwesterly winds and mixing of cold subsurface waters. However, the Bay of Bengal remains favourable for cyclogenesis. The post-monsoon season is the major cyclone season in the North Indian Ocean

Warming of the Indian Ocean: Climate change is amplifying the warming of the Indian Ocean, with more heat being transferred from the Pacific Ocean and Southern Ocean. This increases the overall sea surface temperature (SST), crucial for cyclone formation.
Monsoon and cyclones: The warming affects the monsoon patterns and has the potential to change cyclone intensity. More heat and moisture from the warming seas lead to more energy available for cyclones.
Impact on global ocean circulation: The warming of the Indian Ocean is also affecting global ocean currents, impacting heat uptake by the Pacific Ocean and water sinking in the North Atlantic. The Indian Ocean is playing a central role in global climate change processes.

Strengthening Early Warning Systems: Enhance real-time monitoring and forecasting of cyclones, particularly in the pre- and post-monsoon seasons, using satellite data and advanced models.
Building Climate Resilience: Implement climate adaptation strategies, especially for coastal communities, by improving infrastructure and disaster preparedness to cope with increasing cyclone intensity due to climate change.

Mains PYQ:

Q Discuss the meaning of colour-coded weather warnings for cyclone prone areas given by India Meteorological Department. (UPSC IAS/2022)