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| Abstract Submission No. | ABS-2022-02-0190 |
| Title of Abstract | Marine heatwaves over the tropical Indian Ocean and their interaction with the Indian summer monsoon |
| Authors | J. S. Saranya, M K Roxy*, Panini Dasgupta, Ajay Anand |
| Organisation | Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Pune 411008, India |
| Address | Indian Institute of Tropical Meteorology, Pune 411008, India Pune, Maharashtra, India Pincode: 411008 Mobile: 9405015676 E-mail: saranyaozhoor@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Marine heatwaves (MHWs) are extremely warm sea surface temperature (SST) events in the ocean (above the 90th percentile threshold) that have an unprecedented impact on the marine environment. Recently, studies have started examining the cause of the genesis of these MHWs and their effects on the marine environment in different parts of the global ocean. However, only limited studies have been carried out in the tropical Indian Ocean. This study looks into the genesis and trend of MHWs in the tropical Indian Ocean during 1982⿿2018 and their interaction with the Indian summer monsoon. We observe that the increased warming in the Indian Ocean has a significant role in exacerbating the number of MHWs. Moreover, the El Niño variability has a notable influence on the occurrence of MHWs during the summer monsoon. The Indian Ocean warming and the El Niño variability are the culprits behind the occurrence of some of the strongest and long-lasting MHWs in the tropical Indian Ocean. During the summer monsoon period, the western Indian Ocean (WIO) region and the north Bay of Bengal experienced the largest increase in MHWs at a rate of 0.4⿿0.5 events per decade. The increased solar radiation, relaxation of winds, and reduced evaporative cooling are the local factors that induced the MHWs in both regions. The increased solar radiation, relaxation of winds, and reduced evaporative cooling are the local factors that induced the MHWs in both regions. Moreover, in the western Indian Ocean, the tranquillity in winds leads to decreased heat transport by ocean currents from the near-equatorial regions towards the north. This study highlights that the MHWs in the western Indian Ocean and the north Bay of Bengal are associated with a decreased monsoon rainfall over the central Indian landmass. On the contrary, MHWs in the Bay of Bengal led to an increased summer monsoon rainfall over southwest India. |