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Abstract Submission No. | ABS-2022-10-0338 |
Title of Abstract | Indian Ocean SST records show decoupling of Southwest and Northeast Monsoon during abrupt climate shifts |
Authors | Champoungam Panmei*, Divakar Pothuri Naidu |
Organisation | Indian Institute of Technology Roorkee |
Address | Department of Earth Sciences, IIT Roorkee Roorkee, Uttarakhand, India Pincode: 247667 Mobile: 9657512967 E-mail: cpanmei@es.iitr.ac.in |
Country | India |
Presentation | Oral |
Abstract | Indian monsoon fluctuation events and variability trends have been studied by precise reconstructions of sea surface temperatures of the past which have great implications for understanding the dynamics and possible mechanisms associated with it. On one hand, Indian monsoon variability (inferred for southwest monsoon; SWM) was reconstructed for the past ~14 kyr through oxygen isotopes and Mg/Ca-derived sea surface temperatures (SSTs) using planktonic foraminifera Globigerinoides ruber from a western Bay of Bengal (BoB) sediment core MD 161/17 located off Krishna-Godavari rivers. On the other hand, variability of winter cooling in the northeastern Arabian Sea (Core SK 239, located off Gujarat) and the associated northeast monsoon (NEM) strength over the last ~37 kyr BP were reconstructed using SSTs derived by artificial neural network technique (ANN), based on planktonic foraminiferal species abundance data. While the BoB SST show warming during colder Younger Dryas (YD), the north Arabian Sea winter SST anomalies cooled during periods of abrupt climatic shifts like YD and Heinrich Events (H1, H2, H3) which were documented in the Greenland climate record, implying 1). a decoupling between the SWM and NEM during these events, and 2). a remote forcing of the north Arabian Sea winter cooling and NEM strength with a coeval warming of the tropical Indian Ocean in the BoB during these shifts. This is possible through atmospheric teleconnections driven by AMOC changes because AMOC changes being associated with boundary conditions in the north Atlantic, reposition the ITCZ southward (northward) during cold (warm) boundary conditions (viz. YD, H1, H2, H3) resulting in strengthening (weakening) the NEM and weakening (strengthening) the SWM. |