Modelling the late Holocene and future evolution of Monacobreen, northern Spitsbergen

Oerlemans, Johannes

doi:https://doi.org/10.5194/tc-12-3001-2018

Articles | Volume 12, issue 9

https://doi.org/10.5194/tc-12-3001-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-12-3001-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 12, issue 9

Research article

|

21 Sep 2018

Research article |

| 21 Sep 2018

Modelling the late Holocene and future evolution of Monacobreen, northern Spitsbergen

Johannes Oerlemans

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Final revised paper (published on 21 Sep 2018)
Preprint (discussion started on 16 Feb 2018)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of Oerlemans 2018: "Modelling the late-Holocene and future evolution of Monacobreen, northern Spitsbergen"', Anonymous Referee #1, 21 Mar 2018
- AC1: 'Response to comment by Anonymous Referee #1', Johannes Oerlemans, 23 Mar 2018
  - RC2: 'Follow-up to initial review and response to review', Anonymous Referee #1, 26 Mar 2018
RC3: 'Review of ‘Modelling the late-Holocene and future evolution of Monacobreen, northern Spitsbergen’', Anonymous Referee #2, 19 Apr 2018
- AC2: 'Response to Ref. 2', Johannes Oerlemans, 24 Apr 2018

Peer-review completion

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

AR by Johannes Oerlemans on behalf of the Authors (26 Jun 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Jun 2018) by Valentina Radic

RR by Anonymous Referee #1 (07 Jul 2018)

Suggestions for revision or reasons for rejection

In general, the author has responded to my major critiques of their original manuscript and improved the overall quality of this manuscript. However, without a detailed author's response document, which should include point-by-point responses to the original review, as required by The Cryosphere's guidelines (https://www.the-cryosphere.net/for_authors/manuscript_preparation.html), it is difficult to determine whether they have responded to my original suggestions. Looking through the new version of the manuscript however, I can find many instances where basic edits from the first review have not been fixed in this new manuscript. Though I certainly respect the author's right to not make edits that they do not agree with, some of the ignored suggestions have to with basic things like equations with inconsistent units and confusing formulations. In cases where the author disagrees with my review and decides not to make those edits, it would be helpful to have an explanation.

Points from first review that were not addressed:

2. Write S(t) and \bar{s}(L) in equation 3 to make functional dependencies clear.

3. What is the physical reason that tributaries only supply mass to the main stream when they have a positive budget? Should the mass supply occur simply whenever ice flows from the tributaries to the main stream? Won’t this occur even if the tributary mass balance is negative?

5. Equation 10: Should this equation read H_f = H_m * max(kappa, delta) ? The units don’t make sense as it is currently written.

7. The surge function as formulated in equation 14 is an exponential function that describes a single surge, but not the periodicity of surges. The periodicity should be included in the equation itself, otherwise the reader has to figure out that t_0 is itself a regularly-spaced set of surge onsets, which is not so clear.

8. The fact that there is a single observation of a terminus position from 100 years before the only observed surge does not uniquely prove that the surge period is 100 years. As you say, there is no proof that a surge ended exactly in 1907 when the terminus position was observed. Even if it had, this could mean that the glacier has a surge period that is some whole fraction of 90 (1997 - 1907), like 3 surges of 30 year period or some period greater than 90. Also, it is possible that the surge period changes as the glacier retreats (e.g. because surface mass balance changes considerably).

Section 2.5: this is not part of the model description, therefore shouldn’t be included in section 2.

-It is not necessarily the case that overdeepenings cause hysteresis.

Line 298: explain why this observations puts a lower limit on ELA

Other Major points:
-It would perhaps be helpful to do a close revision (or have another person do a close read) of the manuscript for grammatical and spelling errors. There are many places where punctuation (commas mostly) are needed to separate off transitional statements at the beginning of sentences. Also, new paragraphs often seem to start in odd places. I have attempted to find all the spelling errors, but these should have been fixed before review.

-I still find the abstract to be too long and including too many details about the study. Perhaps you can pick the 3-5 most important results of the study and condense the abstract to highlight those. Otherwise, it is difficult for the reader to determine the most importance results from the abstract.
-Line 99: given that "flowband" is typically used to refer to models that resolve thickness and velocity horizontally along the glacier flow, this statement is misleading. I would suggest using the term "lumped" or "box" to refer to the model, which has a single prognostic variable for the entire distance downstream.

Other Minor points:
Lines 38-44: The first paragraph could be condensed into two sentences.
Line 50: remove “very much”
Line 55: be more specific than “entire glacier population”
Line 56: A different line from what? Be more specific at the beginning of a new paragraph.
Line 63: “Three-dimensional”
Line 64: “the issue of boundary conditions in steep terrain has not yet been resolved in a satisfactory way” - be more specific
Line 71: MGMs require few computational resources
Line 76: In this paper, a MGM...
Line 79, 87: substitute "difficult" for "a real challenge"
Line 91: "The larger glacier systems on Svalbard presumably have long response times" - provide a citation or some reasoning behind this statement
Line 103: delete "it is clear that"
Line 120: S is the "surge function" (described at length in section XX), then remove "The form of S(t) will be described later." on line 123
Line 123: Cite Oerlemans 2011 here
Line 125: delete "apparently"
Line 145: Euler scheme of what order? (I assume first - state this)
Line 145: Tests
Line 146: replace "a" with "year" throughout the paper
Line 151: cite needed
Line 155: Equilibrium line altitude is used as climate forcing to the glacier model (to be discussed later).
Line 168: Comment on uncertainties associated with estimation of topographic parameters using this method.
Line 174: delete "The formulation of a calving law has been a controversial issue since a long time."
Line 194: It should be noted that comprehensive numerical models have not yet been used to validate...
Line 203: Should this title read "main stream"
Line 209: "is not met"
Line 243: "is no exception"
Line 245: Compared to the glacier length,
Line 271: respectively
Line 303: there has been a long-term trend
Line 304: response time scale
Line 304: Where do you get this time scale from?
Line 321: anomalies
Line 335: successful
Line 373: delete apparently
Line 377: loss
Line 431: projections of future climate change scenarios
Line 469-470: Why is this comparison interesting?
Line 502: observed

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ED: Reconsider after major revisions (09 Jul 2018) by Valentina Radic

AR by Johannes Oerlemans on behalf of the Authors (27 Jul 2018) Manuscript

ED: Publish subject to minor revisions (review by editor) (10 Aug 2018) by Valentina Radic

AR by Johannes Oerlemans on behalf of the Authors (15 Aug 2018) Author's response Manuscript

ED: Publish as is (26 Aug 2018) by Valentina Radic

AR by Johannes Oerlemans on behalf of the Authors (30 Aug 2018)

Short summary

Monacobreen is a 40 km long surge-type tidewater glacier in northern Spitsbergen. The front is retreating fast. Calculations with a glacier model predict that due to future climate warming this glacier will have lost 20 to 40 % of its volume by the year 2100. Because of the glacier's memory, much of the response will come after 2100, even if the climatic conditions would stabilize.