PCLM-D-24-00313

Antarctic Oscillation: Its Influence on the Interannual Variability of Precipitation in the Indian Monsoon Region

PLOS Climate

Dear Dr. Castillo Rodríguez,

Thank you for submitting your manuscript to PLOS Climate. After careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

In particular, the reviewers ask for illustrating possible mechanisms about the link between the Antarctic oscillation and the Indian precipitation; there are also suggestions about the use of different (more independent and/or more suitable) datasets in the study.

Please submit your revised manuscript by Apr 17 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at climate@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pclm/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Andrea Storto

Academic Editor

PLOS Climate

Journal Requirements:

1. We ask that a manuscript source file is provided at Revision. Please upload your manuscript file as a .doc, .docx, .rtf or .tex.

2. Figures 1 to 12: please (a) provide a direct link to the base layer of the map (i.e., the country or region border shape) and ensure this is also included in the figure legend; and (b) provide a link to the terms of use / license information for the base layer image or shapefile. We cannot publish proprietary or copyrighted maps (e.g. Google Maps, Mapquest) and the terms of use for your map base layer must be compatible with our CC-BY 4.0 license.

Note: if you created the map in a software program like R or ArcGIS, please locate and indicate the source of the basemap shapefile onto which data has been plotted.

If your map was obtained from a copyrighted source please amend the figure so that the base map used is from an openly available source. Alternatively, please provide explicit written permission from the copyright holder granting you the right to publish the material under our CC-BY 4.0 license.

Please note that the following CC BY licenses are compatible with PLOS license: CC BY 4.0, CC BY 2.0 and CC BY 3.0, meanwhile such licenses as CC BY-ND 3.0 and others are not compatible due to additional restrictions.

If you are unsure whether you can use a map or not, please do reach out and we will be able to help you. The following websites are good examples of where you can source open access or public domain maps:

* U.S. Geological Survey (USGS) - All maps are in the public domain. (http://www.usgs.gov)

* PlaniGlobe - All maps are published under a Creative Commons license so please cite “PlaniGlobe, http://www.planiglobe.com, CC BY 2.0” in the image credit after the caption. (http://www.planiglobe.com/?lang=enl)

* Natural Earth - All maps are public domain. (http://www.naturalearthdata.com/about/terms-of-use/)

Additional Editor Comments (if provided):

As outlined by the reviewers, the link between the Antarctic Oscillation index and precipitation patterns over the Indian sub-continent requires some more convincing theoretical basis. This may be addresses through literature citations and/or speculation abut possible mechanisms.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does this manuscript meet PLOS Climate’s publication criteria? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript on Antarctic Oscillation: Its Influence on the Interannual Variability of Precipitation in the

Indian Monsoon Region authored by Rodrigo Castillo Rodríguez et al, deals the statistical analysis between the Antarctic Oscillation Index (AAOI) and Indian precipitation patterns. The concept of the paper seems to be novel in the context of two scenarios comprised of radiation and polar vortex, identifying the connection to the Indian monsoon, particularly north east rainfall.

However, I have some concerns on the selection of data sets, methodology and discussion parts.

The authors have used the gridded data sets for AAOI, ONI etc., while the rainfall data sets are based on just 306 rain gauges. I am sure that the authors aware that India Meteorological Department (IMD) developed the gridded data sets (0.25 x 0.25) over India for a period of 1951 to 2021 and are available free (the methodology developed for these data sets can be found from Pai et al, 2014, Mausam). Utilization of these data sets will be more appropriate for the current study.

The authors used the Pearson correlations to report the relation between the AAOI and rainfall. The physical link between rainfall and AAOI which can not be done simply by correlation analysis. The authors need to elaborate how the southern hemisphere annual mode / aaoi are connected to the changes during northeast monsoon season.

The discussion part is lacking the support of existing literature.

The information on climate of India and different seasons is not required.

In light of the above comments, I suggest the paper should undergo major revision.

Reviewer #2: Comments on PCLM-D-24-00313: Antarctic Oscillation: Its Influence on the Interannual Variability of Precipitation in the Indian Monsoon Region

Authors investigate the influence of the Antarctic Oscillation (AAO) on the interannual variability of precipitation in the Indian monsoon region. The study utilizes Pearson and partial correlation techniques, along with moisture transport analysis, employing model, reanalysis and observed datasets such as the FLEXPART model, ERA reanalysis, PERSIANN-CDR, and surface rain gauge stations. The manuscript aims to resolve discrepancies in existing literature by employing a comparative analysis across different seasons.

The attempt is commendable and has been presented well, however certain issues and concerns need clarification and should be addressed before the manuscript could be considered further.

Specific comments:

1) Authors highlight a significant influence of the AAO on precipitation variability over India. However, the existing literature primarily focuses on the ENSO and IOD as dominant modulators of monsoonal precipitation. Any physical mechanism of how AAO impacts the rainfall over India has not been brought out clearly. At present, the manuscript does not provide a sufficiently strong theoretical foundation linking the AAO directly to Indian monsoon variability. The study primarily relies on Pearson correlation and partial correlation analyses to infer causality between the AAO and precipitation anomalies. The manuscript should provide a plausible mechanism for all the qualitative and quantitative arguments presented.

2) Several prior studies have examined the role of large-scale climate oscillations in Indian monsoon variability, with a primary focus on ENSO and IOD. This manuscript does not provide compelling evidence that the AAO exerts a stronger or independent influence compared to these well-established climate drivers. Although partial correlation analyses attempt to account for ENSO, the methodology does not rigorously establish the independent role of the AAO. Without a more detailed multivariate approach, the findings risk being confounded by ENSO-related variability. At least this aspect should be discussed as a limitation.

3) The study employs moisture sink values from the FLEXPART model, ERA5 reanalysis, and PERSIANN-CDR precipitation data, covering different temporal and spatial resolutions. Could the authors also include some discussions/quantifications about the accuracy of moisture sink values.

4) The manuscript presents statistically significant correlations between the AAO and precipitation in certain sub-divisions of India. However, these correlations are weak and vary across different seasons. Acknowledge the weak and inconsistent correlations found in and avoid overinterpreting results. Also, the discussion attributes significant climate variability to the AAO without adequately demonstrating a physical mechanism. I suggest to at least propose some mechanism.

5) The figures containing India should have correct boundaries around the north. This could be redone in all such figures and the analysis could be modified accordingly.

Minor comments:

• The manuscript is lengthy and includes excessive details on standard meteorological and climate processes, making it difficult to extract key findings. Refine the manuscript by reducing redundant content and improving the clarity of figures and tables.

• The conclusions overstate the significance of the findings and need to acknowledge the methodological limitations. Suggest to improve upon these lines.

• What are those strange bold lines in figure 6 and so on? It is actually ruining the clarity of figure. Unless it serves any scientific purpose, you should remove it.

• Please make sure to include high resolution images for enhanced clarity and interpretation.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

Do you want your identity to be public for this peer review? If you choose “no”, your identity will remain anonymous but your review may still be made public.

For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Bhupendra Bahadur Singh

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PCLM-D-24-00313R1

Antarctic Oscillation: Its Influence on the Interannual Variability of Precipitation in the Indian Monsoon Region

PLOS Climate

Dear Dr. Castillo Rodríguez,

Thank you for submitting your manuscript to PLOS Climate. After careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please address the remaining request from the reviewer about the region definition and boundaries.

Please submit your revised manuscript by Jul 04 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at climate@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pclm/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Andrea Storto

Academic Editor

PLOS Climate

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments (if provided):

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Does this manuscript meet PLOS Climate’s publication criteria? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: May be accepted.

Reviewer #2: The northern Indian region still lacks the correct boundaries. I suggest authors to please include a correct one.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

Do you want your identity to be public for this peer review? If you choose “no”, your identity will remain anonymous but your review may still be made public.

For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Antarctic Oscillation: Its Influence on the Interannual Variability of Precipitation in the Indian Monsoon Region

PCLM-D-24-00313R2

Dear Mr. Castillo Rodríguez,

We are pleased to inform you that your manuscript 'Antarctic Oscillation: Its Influence on the Interannual Variability of Precipitation in the Indian Monsoon Region' has been provisionally accepted for publication in PLOS Climate.

Before your manuscript can be formally accepted you will need to complete some formatting changes, which you will receive in a follow-up email from a member of our team. 

Please note that your manuscript will not be scheduled for publication until you have made the required changes, so a swift response is appreciated.

IMPORTANT: The editorial review process is now complete. PLOS will only permit corrections to spelling, formatting or significant scientific errors from this point onwards. Requests for major changes, or any which affect the scientific understanding of your work, will cause delays to the publication date of your manuscript.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they'll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact climate@plos.org.

Thank you again for supporting Open Access publishing; we are looking forward to publishing your work in PLOS Climate.

Best regards,

Andrea Storto

Academic Editor

PLOS Climate

***********************************************************

Additional Editor Comments (if provided):

Reviewer Comments (if any, and for reference):