PCLM-D-23-00056

Downscaled seasonal forecasts for the California Current System: Skill assessment and prospects for living marine resource applications

PLOS Climate

Dear Dr. Jacox,

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 submit your revised manuscript by Jun 10 2023 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,

Liqiang Xu

Academic Editor

PLOS Climate

Journal Requirements:

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. 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: Partly

Reviewer #2: Yes

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

Reviewer #1: Yes

Reviewer #2: Yes

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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: No

Reviewer #2: No

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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

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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: Seasonal forecasts of ocean conditions in the California Current System are explored over the longest simulation for a regional model to date. The team explores the regional patterns and analyze the predictive skill of many physical variables relevant to habitat and marine resources. They paper is extremely well written, the figures are clear, and the story is for the most part very clean. The work would benefit from a clarification about the role of ENSO in their results. For the most part they rely on other works for that connection and do not present any new information on that topic within the results here. This seems like the most important thing they could add to the story. Specifically, the group relies on the role of winter in providing ENSO-related predictability (Lines 441-443, for example -which is well established in the Pacific broadly), but it would be great to show specifically that was the case here. One way the group could do this is by looking at the relationship to the winds following on the work in Jacox et al. (2019) – one of the works they rely on in the results here. The winds seem to have poor predictive skill in the figures here despite having clear ENSO phase related skill as reported in Jacox et al. (2019). Could the results here be similarly grouped into ENSO phases as they were in that work? In contrast to the results described in the text, the July initialized SSH predictive skill looks to be even stronger than the January initialized forecast, which suggests winter is potentially not the entire story. Notably, the fact that the winds are the main ENSO winter teleconnection, but the winds don’t seem to have much predictive skill overall, but SSH does – in itself suggests one mechanism described previously Jacox et al. (2020) that does not rely on the atmospheric bridge but is more oceanic in origin. It suggests the forecast is performing better because of oceanic teleconnections, not atmospheric ones. This could be a result of model construction – but the team has results from a coarser resolution and more resolved atmospheric product to try and tease this out. Meaning – is that just because the winds are better forecast or simulated even in a higher resolution atmospheric product. Or do you require a coupled one. Some of this is beyond the scope of this work for sure, but it would be great fodder for the discussion section and some additional analysis along these lines would be very illuminating.

Second, the model evaluation is not presented here or referenced elsewhere for the base historical analysis used in this work. Given the breadth of this group’s work, this seems straightforward to address for some variables more than others. The MLD performance in particular would be good to know more about in terms of performance. Specifically, does the reanalysis do a better job with this variable or is this variable just difficult to simulate in the region, in general. While the group showcases a couple of time series that are very coastal, albeit long for SST and SSH, as the authors point out, this is a difficult test for this resolution of a simulation. The more subsurface and water column integrated metrics might be a better test. Are there data sets from CALCOFI and the Newport line that could be used to assess the climatological or interannual performance of the historical simulation? Please also be aware of the new coastal products released by NCEI here:

https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0270962.html

Third, more details about the bias-corrected forcings would be good to know. In particular, is it the use of higher resolution forcings or the bias correction themselves that delivers the improvements described in their results?

Finally, Figure 1 and prior work from this group sets a precedent for subregional analysis. This is not necessary per se as the analysis done here is certainly substantial – but understanding how these variables vary spatially within the CCS over time would be very interesting to the regional forecasting community and may help further understand the underlying dynamics of the system.

Overall this is a lot of work and has enormous potential to be a substantial contribution to the field, but the suggestions I have are not minor, so I am suggesting major despite the fine quality of the manuscript. I think the field has moved past if these conditions are predictable on this timescale in this system, and now some refinement of that understanding is in order and this work has enormous potential to do that.

Minor comments and concerns:

Line 399-400: What is meant by “well known” here, please clarify.

Line 409-410: Can you clarify what you mean by improvements here? You show many skill metrics and it would be helpful to know how they improved. Can you show it in supplemental?

Lines 462-464: Can you add a figure or table reference to refer the reader to in order to support this result about higher ACCs for some variables?

Lines 464-466: Can you add a figure or table reference to refer the reader to in order to support this result of performance gains from the high resolution initialization?

Figure 3-6: Please clarify in the caption which version of the forecasts are shown (BC or not?).

Figure 7 and 8: Please add some basic correlations or other statistics of performance to the SST anomaly and SL anomaly comparison time series. Not sure what the panels on the right add to these figures. Together they currently don’t tell a story. Maybe with statistics one will emerge?

Reviewer #2: Ocean forecast is of great significance for understanding future changes for human society. The work entitled “Downscaled seasonal forecasts for the California Current System: Skill assessment and prospects for living marine resource applications” by Jacox described and assessed a ~30 years of retrospective seasonal forecasts for the California Current System (CCS). The author also examined possible impacts of ENSO on ocean current in the study area. The work is well designed, and the manuscript is well written. I suggest a minor revision.

Some other points:

Study area of this work is the California Current System (CCS). However, the authors did not provide sufficient information about this area in introduction of the manuscript. I suggest the author team emphasize the CCS in an approximate way. This is important as Plos Climate has a very wide readership, and some of the them may lack sufficient knowledge about it.

For data availability, the authors mentioned that “code to reproduce figures and tables will be made available in a GitHub repository upon publication.” I suggest the authors make the code available before publication of this work.

Can the authors write a brief summary of this work. A section of conclusion might be helpful for this.

There are some mistakes for the cited references, for example:

Line 563: Volume or issue numbers seems missing.

Line 564-566: Format of this reference is inconsistent to others.

And some others in the reference list also have this problem.

Although Plos Climate may not have a strict requirement on reference styles for the first round of submission, formats of the should be consistent at least.

Caption of Fig. 2 is long. Can the authors make it a little bit shorter?

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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: No

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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-23-00056R1

Downscaled seasonal forecasts for the California Current System: Skill assessment and prospects for living marine resource applications

PLOS Climate

Dear Dr. Jacox,

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 submit your revised manuscript by Sep 20 2023 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,

Liqiang Xu

Academic Editor

PLOS Climate

Journal Requirements:

1. 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.

2. Please amend your detailed Financial Disclosure statement. This is published with the article. It must therefore be completed in full sentences and contain the exact wording you wish to be published.

a. State the initials, alongside each funding source, of each author to receive each grant.

b. State what role the funders took in the study. If the funders had no role in your study, please state: “The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.”

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If you did not receive any funding for this study, please simply state: “The authors received no specific funding for this work.”

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4. We noticed that you used "not shown" in the manuscript. We do not allow these references, as the PLOS data access policy requires that all data be either published with the manuscript or made available in a publicly accessible database. Please amend the supplementary material to include the referenced data or remove the references.

Additional Editor Comments (if provided):

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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: (No Response)

Reviewer #2: All comments have been addressed

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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: (No Response)

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

Reviewer #1: Yes

Reviewer #2: (No Response)

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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: (No Response)

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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: (No Response)

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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: The authors have done a great job at addressing most of my concerns. It seems one of my comments was not well conveyed so I will try again. The following conclusion in the abstract:

“Ocean conditions tend to be more predictable in the first half of the year, owing to greater persistence for forecasts initialized in winter and dynamical forecast skill consistent with winter/spring influence of the El Niño–Southern Oscillation (ENSO) for forecasts initialized in summer. “

This idea is perpetuated throughout the paper, however everything after “owing” in that sentence is conjecture. In some instances it is softened with “consistent with” etc, but mostly it reads like those results are present in this manuscript, and they are not. The authors need to consider softening the language around this connection to ENSO or providing an analysis that more securely links the two. There are other plausible reasons why winter months might provide predictive skill to the summer months -these are explored of course in Jacox et al. (2020) and Ray et al. 2020 and 2022. They don’t all rely on ENSO, but do also suggest the oceanic teleconnections are more important to predictability on this timescale. Ray et al. (2022), in particular, concluded that the local advection and winter reemergence mechanisms contributed the most to subsurface predictive skill in the N-CCS in particular. This reference needs to be added throughout the manuscript where relevant alongside the ENSO teleconnection idea if the authors decide not to provide additional analyses to identify the ENSO teleconnection as the likely main contributor to the predictive skill. Do the authors suggest by their results now, that the system will not work well in neutral years? This needs to be clarified before publication.

As for the analyses they did – it is super interesting and indeed shows the importance of oceanic teleconnections. Thank you for pursuing that idea. I think the paper is much more interesting for it and love the additional figures and work that the author team has worked hard to add. Well done.

Ray, S., Siedlecki, S. A., Alexander, M. A., Bond, N. A., & Hermann, A. J. (2020). Drivers of subsurface temperature variability in the Northern California Current. Journal of Geophysical Research: Oceans, 125, e2020JC016227. https://doi.org/10.1029/2020JC016227

Ray, S., Bond, N., Siedlecki, S.A., & Hermann, A. J. (2022). Influence of winter subsurface on the following summer variability in Northern California Current System. Journal of Geophysical Research: Oceans, 127, e2022JC018577. https://doi.org/10.1029/2022JC018577

Reviewer #2: The authors have elaborated all my concerns, and the present version could be published.

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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

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[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.

Downscaled seasonal forecasts for the California Current System: Skill assessment and prospects for living marine resource applications

PCLM-D-23-00056R2

Dear Dr. Jacox,

We are pleased to inform you that your manuscript 'Downscaled seasonal forecasts for the California Current System: Skill assessment and prospects for living marine resource applications' 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,

Liqiang Xu

Academic Editor

PLOS Climate

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Reviewer Comments (if any, and for reference):