Interannual variability of summer surface mass balance and surface melting in the Amundsen sector, West Antarctica

Donat-Magnin, Marion; Jourdain, Nicolas C.; Gallée, Hubert; Amory, Charles; Kittel, Christoph; Fettweis, Xavier; Wille, Jonathan D.; Favier, Vincent; Drira, Amine; Agosta, Cécile

doi:https://doi.org/10.5194/tc-14-229-2020

Articles | Volume 14, issue 1

https://doi.org/10.5194/tc-14-229-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-14-229-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 1

Research article

|

27 Jan 2020

Research article |

| 27 Jan 2020

Interannual variability of summer surface mass balance and surface melting in the Amundsen sector, West Antarctica

Marion Donat-Magnin, Nicolas C. Jourdain, Hubert Gallée, Charles Amory, Christoph Kittel, Xavier Fettweis, Jonathan D. Wille, Vincent Favier, Amine Drira, and Cécile Agosta

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Final revised paper (published on 27 Jan 2020)
Supplement to the final revised paper
Preprint (discussion started on 24 May 2019)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of Donat-Magnin et al.', Anonymous Referee #1, 28 Jun 2019
- AC1: 'Responses Reviewer#1', Marion Donat-Magnin, 27 Sep 2019
  - AC7: 'Responses Reviewer#1.pdf', Marion Donat-Magnin, 27 Sep 2019
- AC4: 'revised_manuscrit_version', Marion Donat-Magnin, 27 Sep 2019
SC1: 'Some shortcomings', David Bromwich, 16 Jul 2019
- AC2: 'Responses David Bromwich', Marion Donat-Magnin, 27 Sep 2019
  - AC8: 'responses.pdf', Marion Donat-Magnin, 27 Sep 2019
- AC5: 'revised_manuscrit_version', Marion Donat-Magnin, 27 Sep 2019
RC2: 'Review', Anonymous Referee #2, 17 Jul 2019
- AC3: 'Responses Reviewer#2', Marion Donat-Magnin, 27 Sep 2019
  - AC9: 'Responses Reviewer#2.pdf', Marion Donat-Magnin, 27 Sep 2019
- AC6: 'revised_manuscrit_version', Marion Donat-Magnin, 27 Sep 2019

Peer-review completion

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

ED: Publish subject to revisions (further review by editor and referees) (02 Oct 2019) by Kenichi Matsuoka

AR by Anna Wenzel on behalf of the Authors (09 Oct 2019) Author's response

ED: Referee Nomination & Report Request started (09 Oct 2019) by Kenichi Matsuoka

RR by Anonymous Referee #2 (30 Oct 2019)

Suggestions for revision or reasons for rejection

The authors faithfully addressed my concerns and apart from the minor comments below, I think this paper is ready for publication.

L177: The text state ~400 km but the map shows a white zone of about 50 km. Which of the two is true? Or does the domain extents further than Figure 1? In any case, something needs to be adjusted.

Figure 5: The authors provides an argument to stop the color scale at 100 mm w.e. per year. I’m not convinced, the other ice shelves are also discussed although in lesser extend. Moreover, I simply do not see the necessity to cut off at 100 mm w.e. per year as it is doable to expand to ~200 mm w.e. per year without loss of clarity. They seem to use now something similar to ncl’s color table cmocean_tempo (thus white, light green, blue, black), but if you use a colormap/color table with more colors, you can show the values up to 200 without losing “signal” for the 10 mm w.e. per year values.

Figure 9c/d & 12c/d: These are a good additions, but it should be explained better what is exactly shown in these panels. The logical place for this explanation is in the running text.

Figure 13: adjust scale of the y-axis that dotted line in e doesn’t get cut off.

Line 990: would “… austral summer, which represents 15% of the annual SMB, and correlations…” not be grammatically better?

Line 1029: “We now discuss” is a bit odd, consider rephrasing into something like “Lastly, we discuss”.

Line 1030 The assumption that you need melt+rainfall to be 2.24 times snowfall before the snowpack saturates conflicts with earlier estimates. Pfeffer, 1991, JGR estimated it to be 0.7, recent observations align with that. I know, that is not saturation with water, but simply filling the pore space with refrozen water. Furthermore, Kuipers Munneke, JoG, doi: 10.3189/2014JoG13J183, made an estimate of when this process may cause ice-shelf collapse. Ice shelf collapse in this region is not as unlikely as the authors suggest now.

Line 1090: rephrase, see comment at 1030.

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RR by Anonymous Referee #1 (05 Nov 2019)

Suggestions for revision or reasons for rejection

Review of Donnat-Magnin

The paper has undergone significant revision and the authors have made several improvements. The new version is generally well-written, including a thorough description of relevant processes, and the version is clearly the result of a substantial amount of work.

Minor Comments

Line 220: Why not directly calculate the SAM index from the MAR pressure fields (and actually, the same for the ASL?)

Line 318: The details of the comparison with the SAMB database should be improved. Those measurements cover lots of different time windows, how was that considered? If it wasn’t, it should be mentioned that that is a possibility for the decreased performance as compared to the snow radar data.

Table 3 and 4: The multiple regression is an interesting addition. It would be more useful if the regression coefficients as well as their individual p-values for each index are listed, so the reader can understand how they interplay.

Line 690: I think care should be taken to also mention the strength of this signal (or lack thereof) as the lagged explained variance still remain very small.

Technical Comments

Page 1, Line 24: consider revising sentence to: Forty percent of the interannual summer SMB variance over the Getz Ice Shelf is explained by the westward ASL longitudinal migrations

Line 66: Change “Understand” to “Understanding”

Line 155: Change to “Amundsen Sea Embayment glaciers”

Line 163: remove the extra comma and parenthesis after Dee et al.

Line 346: change “pronounce” to “pronounced”

Line 348: Please explain what variable it is the MAR overestimates. It’s not clear if its melt or snowfall

Line 400: change to Amundsen Sea sector

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ED: Publish subject to minor revisions (review by editor) (21 Nov 2019) by Kenichi Matsuoka

Dear authors,

Thanks for submitting the revised manuscript. It is reviewed by two referees, both of them are positive to proceed to the publication, after a few more points are addressed satisfactory. I also have some suggestions listed below. Please consider all of these points and submit a revised manuscript together with a marked manuscript and response letter.

[Comments from the editor]
I have an overall impression that the manuscript needs careful proof reading. For example, SMB and DJF need to be used more consistently, rather than both SMB and surface mass balance, and both DJF and December-January-February are used in an interchangeable manner. Also, some figure captions are incomplete. All line numbers below show these in the markup manuscript.

L139: Define DJF here as it appears first time here. It is currently defined at L248.

L203: MAR has 10 km horizontal resolution (L169) so all AWS in your model domain can be located less than 15 km from the MAR grid points. So, I think that first criterion is always met. Please clarify. And show how many AWS are located in the model domain (out of 243 over Antarctica).

L213-214: do you want to say that reflectors detected with airborne radar are dated using firn cores?

L215: Show time span of SMB values in the GLACICLIM SAMBA dataset.

L251-254: revise to “(as also found by Scotte t al., 2019 and Holland et al. 2019). Our analysis found very similar results using NINO3.4 (not shown).” Currently it is unclear who obtained the results with NINO3.4. And “3.4” or “34”?

L328: define RMSE here (its definition in the figure caption is inadequate).

L334-335: Why are less satisfactory results in the inland explained by more flatter, smoother topography there?

L337: change to DJF (also in Fig. 2 caption and elsewhere; once it is defined use it consistently).

L931: make a new paragraph here?

L992: Medley and Thomas (2019), not 2009.

Table 2: where is it cited? Please make sure that all tables are cited in the right order.

Figure 1: add distance bar.

Figure 2, Table S1, Table S2: please clarify that these are daily values (it is said daily at L326 but not explicit enough in the figure and tables).

Figure 3: update the caption. Drainage basins are not shown in the revised figure.

Figs 9, 10, 11: panel a shows IVT along the y axis of this map projection. Then you need to define the map projection used in this paper.

Figure 9: add scale of arrow lengths or at least explain it in the caption. Also explain hatched area more clearly. What kind of significance? And which panels show these hatches (all a-f or only a-d)?

Figure 10: define q, v, p, and g. Similar to Figure 9, clarify this t test and significance.

Figure 11: change “same formula as for SMB” to “same formula as for Fig. 10”. Similar to

Supplement:
Table S1: typo. Change S to S1.

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AR by Marion Donat-Magnin on behalf of the Authors (29 Nov 2019) Author's response Manuscript

ED: Publish as is (12 Dec 2019) by Kenichi Matsuoka

Short summary

Modeling the interannual variability of the surface conditions over Antarctic glaciers is important for the identification of climate trends and climate predictions and to assess models. We simulate snow accumulation and surface melting in the Amundsen sector (West Antarctica) over 1979–2017. For all the glaciers, the interannual variability of summer snow accumulation and surface melting is driven by two distinct mechanisms related to variations in the Amundsen Sea Low strength and position.