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Southern Bay of Bengal: A possible hotspot for CO2 emission during the summer monsoon

Roy, R and Vinayachandran, PN and Sarkar, A and George, J and Parida, C and Lotliker, A and Prakash, S and Choudhury, SB (2021) Southern Bay of Bengal: A possible hotspot for CO2 emission during the summer monsoon. In: Progress in Oceanography, 197 .

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Official URL: https://doi.org/10.1016/j.pocean.2021.102638


During the summer monsoon (June�September), the influence of cyclonic curl of local winds causes the formation of a thermocline dome called the Sri Lankan Dome (SLD) in the southern Bay of Bengal (BoB). In addition, the subsurface flow associated with the Summer Monsoon Current (SMC) brings Arabian Sea-High Salinity Water mass to the southern BoB. We show that both these oceanographic features are enriched in dissolved CO2 with the upper boundary shoaling very close to the surface. We observed episodic deep mixing events leading to entrainment of CO2-rich subsurface water with the mixed layer. CO2 disequilibrium within the top 45 m reached as high as + 404 µatm. Our estimated mixed layer ventilation rates ranged between 2.4 and 4.6 days between sampling stations suggesting equilibration with upwelled waters were still evolving. We also encountered a patch of Arabian Sea-High Salinity Water mass with low aqueous pCO2 suggesting past ventilation. Our modest estimates suggest a grid area of 2° latitude � 2° longitude can trigger a mean release of 0.78 Gg C day�1, which is significantly higher than the estimated new production rates due to upwelled nutrients. Our study illustrates that upwelled water associated with the SLD in conjunction with the barrier layer erosion accompanied with the flow of SMC has the potential to occasionally ventilate in southern BoB. We believe that these processes can negate the region's benefits by acting as a CO2 source which underscores the need for detailed investigation. © 2021 Elsevier Ltd

Item Type: Journal Article
Publication: Progress in Oceanography
Publisher: Elsevier Ltd
Additional Information: The copyright for this article belongs to Elsevier Ltd
Keywords: Atmospheric thermodynamics; Carbon dioxide; Domes; Oceanography; Ventilation, Barrier layers; New production; Sampling stations; Subsurface Flow; Subsurface waters; Summer monsoon; Upper boundary; Ventilation rate, Barium compounds, carbon dioxide; carbon emission; episodic event; monsoon; salinity; subsurface flow; thermocline; upwelling; ventilation; water mass, Arabian Sea; Bay of Bengal; Indian Ocean
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 25 Sep 2021 12:38
Last Modified: 25 Sep 2021 12:38
URI: http://eprints.iisc.ac.in/id/eprint/69790

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