Sensitivity of the pseudo-global warming method under  flood conditions: a case study from the northeastern US

Xue, Zeyu; Ullrich, Paul; Leung, Lai-Yung Ruby

doi:https://doi.org/10.5194/hess-27-1909-2023

Articles | Volume 27, issue 9

https://doi.org/10.5194/hess-27-1909-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-27-1909-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 27, issue 9

Research article

|

15 May 2023

Research article |

| 15 May 2023

Sensitivity of the pseudo-global warming method under flood conditions: a case study from the northeastern US

Zeyu Xue, Paul Ullrich, and Lai-Yung Ruby Leung

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Final revised paper (published on 15 May 2023)
Supplement to the final revised paper
Preprint (discussion started on 22 Jul 2022)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2022-482', Anonymous Referee #1, 10 Oct 2022

I am rejecting this manuscript due to the substantial work needed for revision, but I encourage resubmission due to the interesting topic of this paper. Please see the attached comments for more details.

Citation: https://doi.org/10.5194/egusphere-2022-482-RC1
- AC1: 'Reply on RC1', Zeyu Xue, 13 Oct 2022
  
  Dear Referee,
  Thank you very much for your questions and suggestions. We admit this paper had some issues you mentioned, but we think most issues are not fundamental and are caused by misunderstanding and lack of enough clarification. Therefore, we respond to all general issues and some major specific issues you mentioned in the response letter attached and hope it can address your concern. We will write a point-to-point response after the interactive review process and revise the paper correspondingly.
  Bests,
  Zeyu
  
  Citation: https://doi.org/10.5194/egusphere-2022-482-AC1
- AC3: 'Reply on RC1', Zeyu Xue, 29 Oct 2022
  
  Dear Referee,
  A more detailed and updated response letter has been uploaded. Please have a check.
  Thank you very much for all your suggestions!
  Bests,
  Zeyu
  
  Citation: https://doi.org/10.5194/egusphere-2022-482-AC3
RC2:
'Comment on egusphere-2022-482', Anonymous Referee #2, 12 Oct 2022
This article deals with a hot topic that may suit HESS. This study examines the sensitivity and robustness of the PGW method over NEUS by conducting multiple PGW experiments. In addition, several PGW experiments are conducted to answer the three key questions related to the application of the PGW method. The results may help further understand the impact of different PGW simulations on climate projections. Overall, I think it is a pretty good job. However, some scientific or presentation issues need to be carefully addressed. Therefore, the reviewer recommends that this manuscript should be accepted after minor revision.

Minor revision:

It is recommended to use consecutive line numbers.

It is suggested that some necessary statistical parameters should be provided to quantify the difference in precipitation and temperature simulation performance of different schemes.

The figures legend/caption is not self-explanation, which should be improved. In addition, many subgraphs in Figures 2 and 3 are very similar, making their differences challenging to identify. It is suggested to adopt the form of Figs.8-12 or add the statistical parameters mentioned in question 2.

Figure 1 recommends that the macro location comes from the continent to geologically locate. The locations of the three regions should be marked in Figure 1

Please clarify the "returned" flood period (2055 April to 2056 July). Is this the 50-year return period for floods considered? Why not consider using other periods?

Please check whether Figure 13 is incorrect. Also, please adjust the color bars in Figures 11, 3, and S1, as some of them are not valid.

The authors should rearrange the structures of the manuscript. The discussion is missing, maybe the result should change to result and discussion. You must buy the results from other similar studies in the discussions section. It is worth completing comparisons or differences with similar studies in other regions of the country or the world with related studies.

The authors should further clarify the shortcomings and limitations of the study.

Please check the format of the references to meet the journal's requirements.
Citation: https://doi.org/10.5194/egusphere-2022-482-RC2
- AC2: 'Reply on RC2', Zeyu Xue, 14 Oct 2022
  
  Dear reviewer,
  Thank you so much for your appreciation and all these helpful suggestions. Certainly, these suggestions are very helpful in improving the scientific rigor and presentation of this work. We will revise the paper correspondingly after the interactive review process and provide a detailed point-to-point response letter.
  Bests,
  Zeyu
  
  Citation: https://doi.org/10.5194/egusphere-2022-482-AC2
- AC4: 'Reply on RC2', Zeyu Xue, 29 Oct 2022
  
  Dear Referee,
  A more detailed and updated response letter has been uploaded. Please have a check.
  Thank you very much for all your suggestions and appreciations!
  Bests,
  Zeyu
  
  Citation: https://doi.org/10.5194/egusphere-2022-482-AC4

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Reconsider after major revisions (further review by editor and referees) (20 Nov 2022) by Yi He

AR by Zeyu Xue on behalf of the Authors (24 Dec 2022) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (08 Feb 2023) by Yi He

RR by Anonymous Referee #1 (13 Feb 2023)

Suggestions for revision or reasons for rejection

I appreciate the time the authors took to address my concerns and increase the robustness of their findings. Overall, I find that the manuscript has been greatly improved and thus I have mostly minor comments to suggest.

General comments:
• I am confused about the point of Section 3.3 “Gravity wave noise” because the authors contradict the claims they make in this section with other parts of the paper. In this section, they attribute the appearance of gravity waves to storm development, which I believe is accurate and not noise especially because in the introduction they state that spurious gravity waves could be generated from the boundary of the domain if the perturbation upsets geostrophic balance (lines 61–63). Clearly, these are not just “spurious” gravity waves, but rather real artifacts due to storm intensification upon watching the animations sent by the authors. In the conclusions (lines 356–358), they contradict Section 3.3 and state that all experiments produce spurious waves. You cannot state that these are both spurious and storm-generated gravity waves, they must be one or the other (unless there are other gravity waves I did not see).
o From this point, I think there is too much speculation around the appearance of waves and I would recommend simply stating that they exist, and could be due to stronger storms in the PGW simulations due to the warmer temperatures. Or you could just state that they exist and are stronger with some perturbed variables but not others.

Specific comments:
• Lines 12–13: I do not think you can state the preservation of geostrophic balance does not hold, given my comment about gravity waves.
• Line 48, starting with “In these first PGW”, I recommend starting a new paragraph since the one you have is already quite long.
• Line 136: How are perturbations linearly interpolated? Do you mean the perturbations between months?
• Line 138–140: Are you taking the CESM 40-member ensemble mean for your future forcing? If so, that should be stated here.
• Figure 2 caption: I don’t see a column with the difference with IMERG. Please remove this from the caption or include figures showing this difference.
• Line 189–191: I understand how regional vs gridpoint perturbations in T would cause an impact in the October case due to the reduced land-sea contrast in the regional perturbation, but I don't understand why regional vs. grid point perturbations would affect the frontal system? Do you think it's due to a reduced horizontal temperature gradient using the regional perturbations? If so, these sorts of interpretations would be helpful to discuss in order to make sense of your results.
• Figure 3: Please state that all precipitation products are regridded to the same grid-spacing and what that grid-spacing is.
• Figure 4: Please add “difference” after “PGW_T_gp” in the figure headings in the right column to make it clear that this is a difference plot.
• Figure 6: The titles overlap between the two columns, so I recommend using a smaller font to make sure they do not overlap.
• Lines 240–241, 246–247: Are you referring to Fig. S6 and S7 here? If so, please add those citations.
• Lines 283–284/ “Note that precipitable water is defined as the depth of water in a column of the atmosphere instead of precipitable water in the surface atmosphere”: I am well aware of how precipitable water is defined. I was simply pointing out that the reduction in precipitable water for the PGW_T_SLP_gp experiment mostly appears over the sea rather than the land (except for the 2056 May case), which is worth stating in your results.
• Line 292: I recommend reordering the figures so that Fig. 9 comes after Fig. 13 since this is the first time you mention it.
• Lines 297–300: It is well known that CESM-LE tends to have a very strong warming signal in RCP8.5 compared to other GCMs, so what if the inclusion of SLP perturbations helps to ameliorate those biases?
• Supplementary Table S1: you are missing a citation after CLM4

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ED: Publish subject to minor revisions (review by editor) (12 Mar 2023) by Yi He

AR by Zeyu Xue on behalf of the Authors (22 Mar 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (19 Apr 2023) by Yi He

AR by Zeyu Xue on behalf of the Authors (21 Apr 2023) Manuscript

Short summary

We examine the sensitivity and robustness of conclusions drawn from the PGW method over the NEUS by conducting multiple PGW experiments and varying the perturbation spatial scales and choice of perturbed meteorological variables to provide a guideline for this increasingly popular regional modeling method. Overall, we recommend PGW experiments be performed with perturbations to temperature or the combination of temperature and wind at the gridpoint scale, depending on the research question.