PCLM-D-24-00149

Long-term measurements of seasonal snowpacks indicate increases in mid-winter snowmelt and earlier snowpack disappearance in the northeastern U.S.

PLOS Climate

Dear Dr. Wilson,

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.

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Kind regards,

Zhipin Ai

Academic Editor

PLOS Climate

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Additional Editor Comments (if provided):

I have received two review reports, both of which do recommend it for publications in PLOS Climate. The reviewers listed the issues related to the novelty, the method, and the results/discussion. In general, i agree with their comments. Please modify your paper accordingly.

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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

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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: Yes

Reviewer #2: Yes

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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: Reviewer comments for PCLM-D-24-00149.

This study examined trends in 56 weeks of weekly SWE for eastern U.S. sites in relation to climate variables. This sounds like an awesome dataset. I thank the authors for making their data publicly available. I also liked how the authors made symbols in their figures different beyond color schemes, so that they are more easily accessible.

My main comments focus on narrowing the focus of the work to identify specific novelties and results. One way to do this would be through testable hypotheses focusing on just a few relationships, to help guide the work, rather than performing a large number (~100) of exploratory significance tests. I also suggest some rewording of the introduction, restructuring of results, and inclusion of a Conclusions section to help with this. Further, I think readers would benefit from focusing on effect sizes of the trends in the abstract and text, rather than whether or not they were significant, since significance does not convey how impactful a trend can be. Having such a neat dataset could help focus in on some narrower questions and relationships, leading to more generalizable advances that would increase the impact for readers worldwide.

MAIN COMMENTS:

Page 2, lines 29-33. For the abstract, instead of stating which trends were significant or marginally significant, I think it would be better to state the effect sizes, either in absolute or relative values.

Page 2, line 41 to page 3, line 48. This first intro paragraph discusses existing work about changing sizes and durations of snowpacks. Then, this sentence basically says that more details about it would be useful. I think in this case, it would be better to move the sentence to later in the intro, after the need for more details is explained, and/or refer to the novelty of this study more specifically than a “more detailed understanding.” I liked the statement about the gap of the eastern US not having a SNOTEL-like network, so perhaps it could go after that.

Page 5, line 106. At the very end of the intro, I think it would increase the impact to have a sentence explaining the novelty of the work (in terms of generalizable advancements) and the knowledge gap that it will fill. I think this would make it more applicable to readers outside of the study region. Stating hypotheses that include just a small number of relationships to test could also help clarify the novelty and impact of the work here too.

Page 8, lines 180-181. Since temperature and humidity can have large natural fluctuations (e.g., seasonality), it would be better to have an absolute model evaluation such as mean absolute error, rather than the R-squared. Even if the model is way off, you could still get a decent R-squared just because of the error’s relativity to the large fluctuation in inputs.

Page 9, lines 217-220. I count about a hundred significance tests in this study. Were p-values adjusted for multiple comparisons? With this many tests, I think they should be corrected, to limit the potential for false-positive results. Another way to get around this could be to perform a smaller number of tests so that the need for p-value corrections would be minimized. Focusing more on effect sizes, and possibly 95% confidence intervals of trends (or a similar way to communicate error), would be useful here as well.

Page 11, lines 258-268. Page 12, line 285 to page 13, line 295. Page 14, lines 312-318. In the other results paragraphs, I thought the authors do a good job explaining the sizes of effects/trends, rather than just the p-value. I would like to see the same done for these three paragraphs. Especially when very many significance tests are being performed, I think the sizes of effects become very important to focus on. A significant trend that is tiny would be different from a significant trend that is large and impactful to resource management, so it is important to highlight the effect size.

Also, I feel the design of the work is in need of improvement starting in the 2nd paragraph of the results. Rather than examining specific questions and hypotheses, the study performed a large number of comparisons to see which are significant. Although this is fine for exploration, I do not think it is the best for the paper. I would like to see a few relationships focused in on with more of a narrow narrative. Tables 2, 3, and 4 that show the explorations of the large number of tests could be moved to the supplementary material, and the results displayed in results section tables could be kept to just what is important enough to mention in the text. This could also help reduce the number of significance tests in the results like I described above.

Page 20, line 465. I think this paper would benefit from a Conclusions section, where readers often go to find the most important take-aways. The first and last paragraphs of the Discussion section seem to have conclusions in them, so maybe could form a base for a Conclusions section. Regardless, I think it is important to have a Conclusions section in the paper to increase its impact.

MINOR COMMENTS:

Page 6, lines 134-137. I would be very interested in learning more about how conditions of the snowpack are changing. Like, if SWE stays the same but snow depth decreases and the snow becomes icier. It would not be essential for this work, but maybe for future work if those data exist.

Figure 2. The legend labels are too small and blurry to read. I suggest making them larger and/or crisper.

I wish the authors the best with this work and their future endeavors.

Reviewer #2: General Comments

Introduction:

The introduction is very well done, clear, and easy to read.

Methods:

For calculations and metrics (e.g., snowpack measurements and derived variables; climate variables), I suggest going through methods and pulling out metrics and then clearly defining them in a table. I also suggest pulling out equations and ensuring that they are numbered.

Results: In general, the focus on significance and correlation is interesting, but I would also be interested in the slope of these regressions. In reading through results, I really feel a tabular summary of metrics and seasons with references would be extremely helpful in reading through this. Something like the tables in: Gordon, B. L., Brooks, P. D., Krogh, S. A., Boisrame, G. F., Carroll, R. W., McNamara, J. P., & Harpold, A. A. (2022). Why does snowmelt-driven streamflow response to warming vary? A data-driven review and predictive framework. Environmental Research Letters, 17(5), 053004.

Discussion:

In general, the discussion is compelling. I know this is a nebulous suggestion, but I do think there are spots where some paragraphs could be combined and/or the key points could be more clearly articulated. I found myself getting a bit turned around in the last four paragraphs to be quite honest and wasn’t exactly sure what the point about air temperature was supposed to be. I think re-reading your discussion with the goal of convincing your reader of several main points would really help me when I found myself wandering a bit towards the end. Specifically, and importantly, I found myself wondering what the key winter processes driving observed changes in snowpack were according to the authors. I also think it would be interesting to contrast these results slightly more with scholarship in the WUS, where substantial work has tended to focus, as well as the northeast.

Specific Comments

Line 93: Suggest replacing ‘our region’ with ‘the region’ or something similar as readers are likely not all from the northeastern US. References are throughout the paper.

Line 104-106: Are the descriptors beginning, maximum and disappearance of seasonal snowpack? If so, I recommend rewriting this sentence so that is more explicit.

Line 148: I’m not clear that WINTER needs to be in all caps throughout.

Line 207: I would suggest a table for data to make it easier and references within the table.

Line 213: I would insert a sentence describing what this technique is

Lines 261- 265: If your alpha is 0.05, I’m not sure I track marginally significant versus not significant for SC2 and SC19. I would suggest that those are not significant based on your threshold unless you’ve defined marginal significance elsewhere… It seems like you’re defining based on an alpha of 0.1 and 0.05 based on 280-282, but I do think that this needs to be more clearly stated in the methods in terms of how you’re approaching significance.

Lines 323-331: I would argue that these definitions could be moved into methods and summarized in a table or at least enumerated so that its really easy for your reader to go back and reference them.

Line 389-390: If I’m understanding this correctly, this finding is the opposite of work in the WUS showing that snowmelt occurs at a slower rate under warming: Musselman, K. N., Clark, M. P., Liu, C., Ikeda, K., & Rasmussen, R. (2017). Slower snowmelt in a warmer world. Nature Climate Change, 7(3), 214-219. Could you elaborate on the mechanism behind your observation in the EUS?

Line 398-400: This finding is really interesting given the focus on many papers in the western US on changes in precipitation phase. I wonder if you could delve into this contrast a bit more and potentially expand to consequences for runoff. See contrasting results: Berghuijs, W. R., Woods, R. A., & Hrachowitz, M. (2014). A precipitation shift from snow towards rain leads to a decrease in streamflow. Nature climate change, 4(7), 583-586. And McCabe, G. J., Wolock, D. M., & Valentin, M. (2018). Warming is driving decreases in snow fractions while runoff efficiency remains mostly unchanged in snow-covered areas of the western United States. Journal of Hydrometeorology, 19(5), 803-814.

Line 402: I think there is a typo in this portion of the sentence: “both the number of snow net snow ablation weeks”

Line 417: This seems like an opportunity to discuss metrics that were not tested in this analysis…

Line 420: which metrics?

Line 424-425: Does this factor in humidity at all? See: Harpold, A. A., & Brooks, P. D. (2018). Humidity determines snowpack ablation under a warming climate. Proceedings of the National Academy of Sciences, 115(6), 1215-1220.

Line 434-438: This is a very long topic sentence—can you shorten it?

Figure 2: It’s extremely hard to read the legend.

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Reviewer #1: Yes: Dan Myers

Reviewer #2: No

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Long-term measurements of seasonal snowpacks indicate increases in mid-winter snowmelt and earlier snowpack disappearance in the northeastern U.S.

PCLM-D-24-00149R1

Dear Wilson,

We are pleased to inform you that your manuscript 'Long-term measurements of seasonal snowpacks indicate increases in mid-winter snowmelt and earlier snowpack disappearance in the northeastern U.S.' 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.

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

Best regards,

Zhipin Ai

Academic Editor

PLOS Climate

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Additional Editor Comments (if provided):

Dear authors,

I am pleased to inform you that both reviewers have expressed satisfaction with your revisions, and therefore your paper has been accepted for publication in PLOS Climate.

Reviewer Comments (if any, and for reference):

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

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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: 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

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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: 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: Reviewer comments for PCLM-D-24-00149R1

I believe the authors did a sufficient job addressing my comments. The abstract focuses well on effects, the scope of the writing is more focused, and it is clear what the main takeaways are for readers outside the study area. I have no further comments.

Reviewer #2: I commend the authors on a thorough and thoughtful job of reviewing the comments.

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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: Yes: Dan Myers

Reviewer #2: No

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