Eddy Vertical Structure and Energy in the Southeastern Indian Ocean: Implications for Dissipation and Lifespan

He, Yinghui, Ding, Wenshuo, He, Qingyou, Zhai, Xiaoming, Liu, Tongya, Gong, Yankun, Xie, Jieshuo, Xu, Jiexin, Chen, Zhiwu, Li, Juan, Lin, Pengfei and Cai, Shuqun (2026) Eddy Vertical Structure and Energy in the Southeastern Indian Ocean: Implications for Dissipation and Lifespan. Progress in Oceanography. ISSN 0079-6611 (In Press)

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Abstract

Satellite observations reveal that mesoscale eddies in the southeastern Indian Ocean (SEIO) are highly active and exhibit pronounced spatial variability in their surface characteristics. By combining satellite and Argo float observations, this study investigates the spatial variations in eddy vertical structure and volume-integrated energy in the SEIO, with particular emphasis on their relationship to eddy lifespan. Cyclonic eddies (CEs) display strong regional contrasts, whereas anticyclonic eddies (AEs) vary less. Subsurface-intensified eddies, predominantly cyclonic, feature a density core near 750 m and maximum velocity at ~250 m depth, and mainly originate from the Leeuwin Current System (LCS) and the open ocean south of 30°S. Eddy lifespan is strongly correlated with volume-integrated energy, which is mainly controlled by eddy amplitude and eddy vertical structure. To further interpret this relationship, we examined energy dissipation terms in the eddy energy equations. The eddy energy dissipation term is expressed as a function of eddy structure, allowing us to quantify regional differences in energy decay rates among eddies with distinct vertical structures. In subsurface-intensified eddies, dissipation due to vertical mixing is much weaker than in surface-intensified eddies. Vertical mixing dissipates eddy potential energy more rapidly than eddy kinetic energy, while horizontal mixing shows the opposite tendency. Overall, CEs in the LCS tend to sustain longer lifespans owing to their higher volume-integrated energy and weaker vertical mixing. These findings underscore the pivotal roles of eddy structure and energy in regulating eddy lifespan.

Item Type:	Article
Additional Information:	Data Availability Statement: The Ssalto/Duacs altimeter products were produced and distributed by the Copernicus Marine and Environment Monitoring Service (CMEMS)(http://marine.copernicus.eu). The daily altimetric Mesoscale Eddy Trajectories Atlas product (META3.1exp DT allsat) are produced by SSALTO/DUACS and distributed by AVISO+ (https://www.aviso.altimetry.fr/) with support from CNES, in collaboration with IMEDEA. Argo data were collected and made freely available by the International Argo Program and the national programs that contribute to it. These data are download from the Coriolis Global Data Acquisition Center of France (ftp://ftp.ifremer.fr/ifremer/argo/geo/). The WOA 2018 data set can be found online (https://www.ncei.noaa.gov/data/oceans/woa/WOA18/DATA/).
Uncontrolled Keywords:	mesoscale eddies,eddy vertical structure,subsurface-intensified eddies,indian ocean,eddy lifespan,eddy energetics
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Depositing User:	LivePure Connector
Date Deposited:	07 Aug 2026 09:54
Last Modified:	07 Aug 2026 09:54
URI:	https://ueaeprints.uea.ac.uk/id/eprint/104035
DOI:	issn:0079-6611

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