Tauktae rare, but Arabian Sea to see more cyclones than Bay of Bengal: Murakami
One of the world’s top experts on cyclones, and the first to connect the climate crisis with an increased frequency of cyclones in the Arabian Sea, Hiroyuki Murakami spoke to HT’s Jayashree Nandi
Cyclone Tauktae has impacted all five states of the west coast—Kerala, Karnataka, Goa, Maharashtra and Gujarat. It intensified extremely rapidly from a Very Severe Cyclonic storm on Monday early morning to an Extremely Severe Cyclonic storm by 8.15 am, something that India Meteorological Department hadn’t forecast. A very warm Arabian Sea will result in many more such storms in coming years.
Hiroyuki Murakami, a climate scientist at the US National Oceanic and Atmospheric Administration’ Geophysical Fluid Dynamics Laboratory was among the first to make the linkages between global warming and increase in extremely severe cyclones over Arabian Sea in his paper published in Nature journal in 2017.
Following Nisarga last year, Murakami had told HT that severe cyclones over Arabian Sea are likely to increase specially during the post monsoon season. On Tuesday, in an interview, he said the storm track of Cyclone Tauktae was actually very dangerous for people living on the west coast of India due to strong wind, storm surge, and heavy rainfall and India should be prepared for more such disasters. Excerpts:
Were you tracking the trajectory of Tauktae? What are your thoughts on its features and impact?
Cyclone Tauktae propagated north westward along the western coast of India. In general, the right front quadrant of a storm is an area of strongest wind speed of tropical cyclones. The storm track of Cyclone Tauktae was actually very dangerous for people living on the west coast of India due to strong wind, storm surge, and heavy rainfall.
Are weather models able to capture rapid intensification of cyclones over Arabian Sea?
Some of the recent weather and climate prediction models capture rapid intensification of cyclones. However, it is still challenging to predict the exact timing of rapid intensification due to the complex nature of rapid intensification.
What causes cyclones to suddenly gain such energy over a short period of time? How does the climate crisis influence development and intensification of cyclones over Arabian Sea?
To reach such high intensity, multiple conditions of both atmosphere and ocean must be favourable. For example, an abnormally warm surface ocean can fuel a storm. Moreover, a sufficiently thick layer of warm water below the surface ocean is required as a necessary condition for intensification. The wind field in the atmosphere is also an important factor for storm intensification.
Is the Arabian Sea warming faster than Bay of Bengal and does that mean more severe cyclones over the west coast of India in coming years?
Climate models commonly project warmer surface ocean in the Arabian Sea than in the Bay of Bengal due to increased emission of green-house gases. This would in turn lead to increased frequency of severe cyclones in the Arabian Sea more than in the Bay of Bengal in the future.
Is it normal for such severe cyclones to develop during the pre-monsoon season in May over Arabian Sea?
It is rare, I think. Tauktae took only 2 days from tropical depression (<17 m/s) to very severe cyclonic storm (VSCS, >32 m/s). The recent case for rapid intensification over the Arabian Sea was Cyclone Vayu in 2019 that took only 36 hours to develop into a VSCS.