Spatial and temporal distributions of surface mass balance between Concordia and Vostok stations, Antarctica, from combined radar and ice core data: first results and detailed error analysis

Le Meur, Emmanuel; Magand, Olivier; Arnaud, Laurent; Fily, Michel; Frezzotti, Massimo; Cavitte, Marie; Mulvaney, Robert; Urbini, Stefano

doi:https://doi.org/10.5194/tc-12-1831-2018

Articles | Volume 12, issue 5

https://doi.org/10.5194/tc-12-1831-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/tc-12-1831-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 12, issue 5

Research article

|

31 May 2018

Research article |

| 31 May 2018

Spatial and temporal distributions of surface mass balance between Concordia and Vostok stations, Antarctica, from combined radar and ice core data: first results and detailed error analysis

Emmanuel Le Meur, Olivier Magand, Laurent Arnaud, Michel Fily, Massimo Frezzotti, Marie Cavitte, Robert Mulvaney, and Stefano Urbini

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Final revised paper (published on 31 May 2018)
Preprint (discussion started on 30 Jun 2017)

Interactive discussion

Status: closed

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

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RC1: 'Review of paper by Le Meur et al.', Elisabeth Isaksson, 16 Aug 2017
- AC1: 'reply to review #1', Emmanuel Le Meur, 18 Aug 2017
RC2: 'Review of Le Meur et al.', Anonymous Referee #2, 08 Sep 2017

Peer-review completion

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

AR by Emmanuel Le Meur on behalf of the Authors (22 Nov 2017) Manuscript

ED: Referee Nomination & Report Request started (04 Dec 2017) by Michiel van den Broeke

RR by Ian D. Goodwin (16 Feb 2018)

Suggestions for revision or reasons for rejection

OVERALL COMMENTS
This paper describes a very solid piece of research. It is a large paper and for the most part, very dense reading. It is essentially a data and error analysis paper that is well supported by the text and scientific logic throughout. It is publishable in that context, and defines a quasi stationary spatial accumulation pattern, as would be expected from interior ice sheet location. However, in its current form it is overly speculative about the wider implications of the data with respect to temporal accumulation rate variability. I do not find those conclusions and speculation supported, given the uncertainty with a number of factors. I detail these as follows.

SPECIFIC COMMENTS
1. The physical mechanisms that produce radar isochrones (internal reflection horizons, IRH’s) are still unknown, yet thought to be linked to acidity and perhaps volcanic fallout horizons. In this paper, the dating of the ice cores has been well constrained by volcanic sulphate horizons. However, the isochrones shown in Figure 2 and so crucial to the papers eventual conclusions are not located at depths where volcanic sulphate horizons occur. So the question remains as to whether they are also the smoothing product of postdepositional processes that concatenate IRH’s at a similar depth interval.
2. The biggest obstacle to inferring temporal accumulation rate variability at these low rates (21-25mm w.e/yr) is the underdetermined firn density profiles along the radar route. Hence, I think that the section 6.2 Time-dependency of accumulation is overly speculative. The temporal rate of change is either at the limit of detectability or below it, depending upon the cumulative errors in its determination. Also, section 6.3 detracts from the paper in that it is using speculation to justify an accumulation trend that may or may not be there. To investigate this, the results need to be evaluated together with the variability in the large scale atmospheric circulation, which is beyond the scope of this already large paper.
3. It is inappropriate at line 979 onwards to talk about rewriting the Antarctic ice sheet’s negative sea-level contribution.
Ian Goodwin

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ED: Reconsider after major revisions (16 Feb 2018) by Michiel van den Broeke

AR by Emmanuel Le Meur on behalf of the Authors (14 Mar 2018) Manuscript

ED: Referee Nomination & Report Request started (19 Mar 2018) by Michiel van den Broeke

RR by Ian D. Goodwin (18 Apr 2018)

ED: Publish as is (18 Apr 2018) by Michiel van den Broeke

AR by Emmanuel Le Meur on behalf of the Authors (27 Apr 2018)

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Short summary

This paper presents surface mass balance measurements from both GPR and ice core data collected during a traverse in a so-far-unexplored area between the DC and Vostok stations. Results presented here will contribute to a better knowledge of the global mass balance of the Antarctic ice sheet and thus help in constraining its contribution to sea level rise. Another novelty of the paper resides in the comprehensive error budget proposed for the method used for inferring accumulation rates.