A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insight
During boreal summer, the Southwest Monsoon Current (SMC) turns northeastward, transporting highly saline water into the Bay of Bengal (BOB) and significantly influencing the dynamics of the upper ocean. Previous studies have shown that an anticyclonic semi-geostrophic (SG) eddy forms on the eastern...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2025-01-01
|
| Series: | Frontiers in Marine Science |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/articles/10.3389/fmars.2024.1504821/full |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850046767120252928 |
|---|---|
| author | Zhou Le M. V. Subrahmanyam Pemmani Venkata Subba Raju Gayan Pathirana Dongxiao Wang Dongxiao Wang Wei Song |
| author_facet | Zhou Le M. V. Subrahmanyam Pemmani Venkata Subba Raju Gayan Pathirana Dongxiao Wang Dongxiao Wang Wei Song |
| author_sort | Zhou Le |
| collection | DOAJ |
| description | During boreal summer, the Southwest Monsoon Current (SMC) turns northeastward, transporting highly saline water into the Bay of Bengal (BOB) and significantly influencing the dynamics of the upper ocean. Previous studies have shown that an anticyclonic semi-geostrophic (SG) eddy forms on the eastern flank of the SMC, this formation associated with the kinetic energy transfer via the barotropic instability (BTI). The presence of such an eddy can attenuate the meridional salinity flux, potentially affecting the development of the circulation within the BOB. Acknowledging the importance of this phenomenon, this study revisits the SG eddy using satellite altimetry data, reanalysis datasets and in-situ observations from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) project. Our 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, while southeastward currents on the eastern edge are structured influenced by CE-like SLA. Further instability analyses indicate that the anisotropic component of BTI is significantly larger than the isotropic component, which is attributed to the weak nonlinear planetary geostrophic convergence of the SG eddy and the strong horizontal shear in mean flow field induced by CE-like SLA. Additionally, our results point out that anomalies in wind stress curl 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. |
| format | Article |
| id | doaj-art-21f29d16627f480db85cd751134e7962 |
| institution | DOAJ |
| issn | 2296-7745 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj-art-21f29d16627f480db85cd751134e79622025-08-20T02:54:23ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452025-01-011110.3389/fmars.2024.15048211504821A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insightZhou Le0M. V. Subrahmanyam1Pemmani Venkata Subba Raju2Gayan Pathirana3Dongxiao Wang4Dongxiao Wang5Wei Song6School of Marine Sciences, Sun Yat-sen University, Zhuhai, ChinaSchool of Marine Sciences, Hainan Tropical Ocean University, Sanya, ChinaCentre for Ocean-Atmospheric Science & Technology, Amity University Rajasthan, Jaipur, Rajasthan, IndiaDepartment of Oceanography and Marine Geology, Faculty of Fisheries and Marine Sciences & Technology, University of Ruhuna, Matara, Sri LankaSchool of Marine Sciences, Sun Yat-sen University, Zhuhai, ChinaSouthern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, ChinaSchool of Marine Sciences, Sun Yat-sen University, Zhuhai, ChinaDuring boreal summer, the Southwest Monsoon Current (SMC) turns northeastward, transporting highly saline water into the Bay of Bengal (BOB) and significantly influencing the dynamics of the upper ocean. Previous studies have shown that an anticyclonic semi-geostrophic (SG) eddy forms on the eastern flank of the SMC, this formation associated with the kinetic energy transfer via the barotropic instability (BTI). The presence of such an eddy can attenuate the meridional salinity flux, potentially affecting the development of the circulation within the BOB. Acknowledging the importance of this phenomenon, this study revisits the SG eddy using satellite altimetry data, reanalysis datasets and in-situ observations from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) project. Our 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, while southeastward currents on the eastern edge are structured influenced by CE-like SLA. Further instability analyses indicate that the anisotropic component of BTI is significantly larger than the isotropic component, which is attributed to the weak nonlinear planetary geostrophic convergence of the SG eddy and the strong horizontal shear in mean flow field induced by CE-like SLA. Additionally, our results point out that anomalies in wind stress curl 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.https://www.frontiersin.org/articles/10.3389/fmars.2024.1504821/fullBay of BengalSouthwest Monsoon CurrentSemi-Geostrophic eddyanisotropyIndian Ocean Dipole |
| spellingShingle | Zhou Le M. V. Subrahmanyam Pemmani Venkata Subba Raju Gayan Pathirana Dongxiao Wang Dongxiao Wang Wei Song A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insight Frontiers in Marine Science Bay of Bengal Southwest Monsoon Current Semi-Geostrophic eddy anisotropy Indian Ocean Dipole |
| title | A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insight |
| title_full | A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insight |
| title_fullStr | A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insight |
| title_full_unstemmed | A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insight |
| title_short | A revisit of the semi-geostrophic eddy east of the Sri Lanka dome with anisotropy insight |
| title_sort | revisit of the semi geostrophic eddy east of the sri lanka dome with anisotropy insight |
| topic | Bay of Bengal Southwest Monsoon Current Semi-Geostrophic eddy anisotropy Indian Ocean Dipole |
| url | https://www.frontiersin.org/articles/10.3389/fmars.2024.1504821/full |
| work_keys_str_mv | AT zhoule arevisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT mvsubrahmanyam arevisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT pemmanivenkatasubbaraju arevisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT gayanpathirana arevisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT dongxiaowang arevisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT dongxiaowang arevisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT weisong arevisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT zhoule revisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT mvsubrahmanyam revisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT pemmanivenkatasubbaraju revisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT gayanpathirana revisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT dongxiaowang revisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT dongxiaowang revisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight AT weisong revisitofthesemigeostrophiceddyeastofthesrilankadomewithanisotropyinsight |