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| Abstract Submission No. | ABS-2022-14-0073 |
| Title of Abstract | Role of marine heatwaves in supercharging tropical cyclones and driving India-Pakistan heatwaves |
| Authors | Roxy M. Koll*, Vineet Kumar Singh, J. Saranya, Y. Sophia |
| Organisation | IITM |
| Address | IITM, Pashan Pune, Maharashtra, India Pincode: 411008 Mobile: 9405015676 E-mail: roxy@tropmet.res.in |
| Country | India |
| Presentation | Oral |
| Abstract | Heatwaves are among the deadliest weather phenomena in northwest India and Pakistan, killing about 350 people annually. Terrestrial heatwaves are projected to increase by six-fold in this region if emissions are to continue⿿which raises concerns for the vulnerable population that is projected to reach 1 billion by 2050. While we know that the frequency and intensity of heatwaves have increased in the region, their driving mechanisms are largely unknown. Here we identify an intriguing interplay between extreme weather events in the marine, atmospheric, and land environments that lead to these deadly events during the pre-monsoon cyclone season (April⿿May). We find that an increasing number of marine heatwaves in the Bay of Bengal⿿riding on rapid ocean warming⿿is energizing tropical cyclones and driving intense heat over the Indo-Pak region. 93% of the cyclones during this season were preceded by marine heatwaves. The duration of marine heatwaves in the basin has increased from about 1 day per year to 6 days per year, while the area covered has increased by 86%, during 1982⿿2019. These marine heatwaves intensify the local convection, enhancing the cyclone updraft by almost twofold over the Bay of Bengal. This anomalous atmospheric circulation leads to subsidence of dry air over northwest India and Pakistan, heating the atmosphere and occasionally driving severe heatwaves. Considering that the rapid warming in the Bay of Bengal is projected to continue into the future, the cascading impacts and interplay between the marine heatwaves, tropical cyclones, and land heatwaves depicted here need to be closely monitored for early mitigation and adaptation. |