Correlation between subsurface salinity anomalies in the Bay of Bengal and the Indian Ocean Dipole and governing mechanisms

Zhang, Zheen; Pohlmann, Thomas; Chen, Xueen

doi:https://doi.org/10.5194/os-17-393-2021

Articles | Volume 17, issue 1

https://doi.org/10.5194/os-17-393-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-17-393-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 17, issue 1

Research article

|

03 Mar 2021

Research article |

| 03 Mar 2021

Correlation between subsurface salinity anomalies in the Bay of Bengal and the Indian Ocean Dipole and governing mechanisms

Zheen Zhang, Thomas Pohlmann, and Xueen Chen

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Final revised paper (published on 03 Mar 2021)
Preprint (discussion started on 07 Aug 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Comment on “Correlation between subsurface salinity anomalies in the Bay of Bengal and the Indian Ocean Dipole and governing mechanisms” by Zhang et al.', Anonymous Referee #1, 13 Sep 2020
- AC1: 'Response to RC1', Zheen Zhang, 26 Oct 2020
RC2: 'Review', Jochen Kämpf, 21 Sep 2020
- AC2: 'Response to RC2', Zheen Zhang, 26 Oct 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Zheen Zhang on behalf of the Authors (29 Oct 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (30 Oct 2020) by Erik van Sebille

RR by Anonymous Referee #2 (09 Nov 2020)

Suggestions for revision or reasons for rejection

The major concern I have regarding this work is that the model does not include the equator. Instead the model uses a sponge layer along the equator, which was not obvious from the discussion paper.

My understanding is that equatorial Kelvin waves play a fundamental role in the variability of the intertropical Indian Ocean. It seems that the model does not include the equatorial forcing that leads to the creation of Wyrtki jets. It has been reported that Wyrtki jets induce coastal Kelvin waves and salinity anomalies in the Bay of Bengal. I cannot see a discussion of this important feature in the paper. Here a reference:

Jing WANG (2017) Observational bifurcation of Wyrtki Jets and its influence on the salinity balance in the eastern Indian Ocean, Atmospheric and Oceanic Science Letters, 10:1, 36-43, DOI: 10.1080/16742834.2017.1239506

I request from the authors a clarification as to whether or not the effect of Wyrtki Jets is included in their study model. If not, I insist that the authors declare the omission of equatorial processes that according to other authors play an important role in the variability of the eastern tropical Indian Ocean and the salinity budget in the Bay of Bengal. Are the missing Wyrtki Jets reflected by errors in the correlations?

The comparison to the IOD presented by the authors is interesting but incomplete. It seems that the model's variability is exclusively derived from the coastal wind forcing (generating coastal Kelvin waves). So, how is the wind forcing along the eastern coasts of the model domain correlated to the wind forcing along the coasts of Sumatra and Java that triggers positive IOD events? Please add more analysis of the underlying wind forcing and its relation to the IOD.

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RR by Anonymous Referee #1 (18 Nov 2020)

ED: Reconsider after major revisions (18 Nov 2020) by Erik van Sebille

AR by Zheen Zhang on behalf of the Authors (23 Dec 2020) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (31 Dec 2020) by Erik van Sebille

RR by Jochen Kämpf (27 Jan 2021)

ED: Publish as is (27 Jan 2021) by Erik van Sebille

AR by Zheen Zhang on behalf of the Authors (28 Jan 2021) Manuscript

Short summary

In this study, we found that the interannual subsurface temperature and salinity variability of the Bay of Bengal (BoB) shows a remarkable delayed correlation with the Indian Ocean Dipole mode. We employed a regional model and determined the contributions of the coastal Kelvin waves and the westward-moving Rossby waves to this correlation. An analysis of the salinity budget revealed that the advection terms dominate the subsurface salinity changes in the BoB.