Tropical cyclone Vayu under climate change scenario RCP 8.5

 

The Northern Indian Ocean has witnessed the genesis of several devastating cyclones over the years due to the typical warm climate. The effect of climate change on these cyclones is an essential topic of research owing to the socio-economic impacts of these cyclones on the coastlines. Climate change is expected to influence the various synoptic parameters of these storms, like translational speed, intensification, frequency, etc. Most of the studies about the impact of climate change on cyclones have been done related to the Atlantic and Pacific Oceans; very few have explored the storms of the Indian Ocean in this context. Considering this context, the present study attempts to understand the track, intensity, and synoptic parameters of Tropical cyclone Vayu-June 2019 under the climate change scenario of RCP 8.5 with the Community Earth Systems Model, CESM data simulated with GPU-based WRF-ARW model. The model is simulated at a 9km single domain with a selected set of physical settings based on the previous studies on the cyclones of the Northern Indian Ocean. The track and intensity of the simulated storm are compared with the present-day hurricane Vayu from the IMD best track estimates.

Interestingly under RCP 8.5, unlike the present-day cyclone Vayu, under RCP 8.5, Vayu would have made landfall along the west coast of India with a sustained wind speed of ~ 15 m/s w. At the same time, he presents a scenario in Vayu weakened over the ocean due to several interactions with the mid-latitude westerlies. The results indicate a considerable change in the future thermodynamics under which Vayu sustained the intensity till landfall. Under RCP 8.5 simulations, the initial posting error is high; other than that, the coming cyclone Vayu seemed to follow a similar track as the present-day storm except for the landfall.

Regarding wind speed intensity, Vayu under RCP 8.5 shows equal wind intensity as that of the present day, with similar underestimation at the mature stage of the storm. The initial results of this study indicate that changes in large-scale thermodynamics in future warming scenarios can influence the modulations in track and intensity of a very severe cyclonic storm like Vayu. Such results highlight the importance of closely monitoring Arabian Sea cyclones to understand the impending disaster mitigations under probable warming scenarios.