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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Physical Oceanography
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1504821

A revisit of the semi-geostrophic eddy east of the Sri Lanka Dome with anisotropy insight

Provisionally accepted
Zhou Le Zhou Le 1Mantravadi Venkata Subrahmanyam Mantravadi Venkata Subrahmanyam 2PV subba Raju PV subba Raju 3Gayan Pathirana Gayan Pathirana 4Dongxiao Wang Dongxiao Wang 1*Wei Song Wei Song 1
  • 1 School of Marine Sciences, Sun Yat-sen University, Zhuhai Campus, Zhuhai, Guangdong Province, China
  • 2 School of Marine Sciences, Hainan Tropical Ocean University, Sanya, China
  • 3 Centre for Ocean-Atmospheric Science & Technology (COAST), Amity University, Jaipur, Rajasthan, India
  • 4 Department of Oceanography and Marine Geology, Faculty of Fisheries and Marine Sciences & Technology, University of Ruhuna, Matara, Sri Lanka

The final, formatted version of the article will be published soon.

    As the Southwest Monsoon Current (SMC) turns northeastward to enter into the Bay of Bengal (BOB), a cyclonic dome develops east off Sri Lanka. Previous research has shown that an anticyclonic semi-geostrophic (SG) eddy can be generated on the further east side of SMC associated with kinetic energy transfer by barotropic instability (BTI). This study revisits the SG eddy using satellite altimetry data, reanalysis datasets and in-situ observations of Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA). The results show that a cyclonic eddy-like (CE-like) negative Sea Level Anomaly (SLA), generated in the eastern BOB due to regional anomalous wind stress curl, also contributes to the formation of the SG eddy. During the formation, mean flows on the northern edge of the SG eddy are strengthened, and southeastward currents on the eastern edge are structured with the influence of CE-like SLA. Further instability analyses indicate that the anisotropic component of BTI is significantly larger than the isotropic one, attributed to the weak nonlinear planetary geostrophic convergence of the SG eddy and the CE-like SLA-induced strong horizontal shear in mean flow field. Additionally, this study points out that wind stress curl anomalies over the eastern BOB and subsequent formation of negative SLA are likely influenced by the Indian Ocean Dipole. These findings suggest that the coupling between SMC instability and regional wind stress curl may play a pivotal role in the generation of SG eddy on interannual timescale, with important implications for regional ocean dynamics.

    Keywords: Mouth region of the BOB, SG eddy, Anisotropy, RAMA observation, Indian Ocean Dipole

    Received: 01 Oct 2024; Accepted: 21 Nov 2024.

    Copyright: © 2024 Le, Subrahmanyam, Raju, Pathirana, Wang and Song. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Dongxiao Wang, School of Marine Sciences, Sun Yat-sen University, Zhuhai Campus, Zhuhai, 519082, Guangdong Province, China

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