Biparjoy part of a new trend in Indian cyclones

Source: The post is based on the article “Biparjoy part of a new trend in Indian cyclones” published in The Hindu on 19th June 2023

What is the News?

The cyclonic disturbances over the North Indian Ocean which includes the Arabian Sea, the Bay of Bengal and the land area in between have gone through many significant changes in recent decades.

What are the changes cyclones have gone through in the North Indian Ocean?

Decrease in the number of cyclones: The number of cyclonic disturbances in the North Indian Ocean has declined considerably over the past four decades.

– This decline was mostly due to a rapid decrease in the number of cyclonic disturbances originating from the Bay of Bengal, the source of most past cyclones to have made landfall in southeast and west Asia. 

– In contrast, the number of such disturbances originating from the Arabian Sea has been steadily increasing in recent years, though the count is still relatively low. 

Greater intensity of cyclones: Global warming is causing the Arabian Sea to heat up, which is resulting in more, stronger cyclones. 

– Data show that about 34% of all disturbances that originated in the Arabian Sea have become severe cyclonic storms (a top speed of >48 knots) compared to the 19% of disturbances which originated from the Bay of Bengal and become severe cyclonic storms. 

– Further, the Indian Meteorological Department finds it tougher to forecast cyclones originating from the Arabian Sea as the models have to be adjusted given the oceanographic differences it has with the Bay of Bengal.