Dear D. Vallot and co-authors,
your manuscript has received two in depth reviews that were in general positive but besides minor issues also highlighted a couple of major issues that should be addressed before publication which concerned in particular, the explanation of the methods and the lacking support from the undertaken modelling on the conclusion of ‘sliding controlling the calving rate’. The minor issues and the more substantial issues have, in my view, been well addressed (sliding control taken out from main conclusions, methods/modelling explained better,…) but as the changes and revisions were rather substantial, I have sent the manuscript out for a re-review (to one of the previous reviewers).

In general the re-review is very positive and highlights the improvements (see detailed comments below) and I agree broadly with the reviewer and therefore the manuscript seems to me close to acceptance.
However, there are still some minor issues identified by the re-review and myself (mostly on time stepping and editing things) that should first be addressed (see detailed lists below).
Further, the re-review makes the more substantial suggestion of clarifying the emphasis of the ‘validation-aspect’ of this manuscript of the HiDEM model for calving (against observations).
I am not sure if a full-restructuring and re-focussing of the main objective to validation of the HiDEM-calving model against observations is really in the sense of the authors, and therefore want to leave some freedom to what degree the authors integrate this comment by the reviewer. As the editor, I think the manuscript would benefit to integrate this ‘validation’ aspect at least to some degree. Maybe in Fig. 2 the HiDEM could also be integrated as it is at the heart of the paper but does rather oddly not appear in the ‘Model schematic’.

Thus before publication in TC I suggest to address:
• at least to some degree address/clarify the validation aspect of the HiDEM model mentioned
• and correct some other minor points listed below


Andreas Vieli (editor) 22 Dec 2017



Comments of re-review
Suggestions for revision or reasons for rejection (will be published if the paper is accepted for final publication)
I have now read this new version of the paper which has indubitably been improved after this first round of reviews. I nevertheless still think that there is room for improvements. After this second careful reading, I really think that the paper should be presented differently. As I now understand the work, I would emphasize that the objective is a validation of the HiDEM model against a datatset, the 5 other models being here "only" to construct the required input fields for this validation, as clearly depicted in Fig. 2 (where HiDEM is the only model which doesn't appear directly in the flow chart). This might require some substantial rewriting at different places of the manuscript to make this clearer. For example, at the bottom of page 5, it should be emphasized that you are using 5 models to build the appropriate input fields for the HiDEM model, in order to compare the modelled calving to the observed one.

Other remarks:
- page 1, line 8: with different discharges.
- page 2, line 23: the previous sentences are general regarding the comparison between continuous and discrete models, and should be clearly separated with the end of the paragraph which is only related to the present study.
- Table 1: you should mention in this table at which observational time is run the discrete model (as one understand later, it is not run at each observational times).
- page 6, line 5: the time step used by Elmer/Ice should be given here. Also, a clear distinction between model time step (1 day for Elmer/Ice as it is mentioned page 7) and observation time (and time step, as mentioned in Table 1) should be made all along the manuscript. For example, line 9, to which "iteration" are you refereeing to? The Elmer/Ice time step iterations or the observational dates?
- page 6, line 11: then, following my main remarks, why just using 4 observational dates for the validation of HiDEM and not extend it to the whole observational series you have?
- page 6, line 16: the output of HiDEM,
- page 7, line 13: More details on the Elmer/Ice modeling
- page 7, line 15: The temporal evolution of the glacier is not only given by equation (2) but also the coupling with the Stokes solution which give the velocity as an input for the evolution of the glacier geometry? Your are never mentioning the forward model used to compute the ice velocity. Regarding the velocity calculation, how is evolved basal sliding during the 11 time step? Especially where it has not been inverted in the case of an advancing front? Also, at other location, is it interpolated between i and i+1 observational dates?
- page 8, line 13: modelled on a 100x 100 m2 grid
- page 9, line 16: advanced front from Elmer/Ice and melt rates from the Plumes model to estimate
- page 9, line 17: You might specify the daily undercutting is subtracted to the front surface only every observational time step?
- Figure 4: The black undercut curve is confusing as only the red and grey ones are discussed in the legend. What does it stand for? Also, the side views show ice foot, and a new colour line should be added to indicate that, as said for the discrete model, ice foot are not accounted for. You should then illustrate on this figure what is the simplified front geometry given as an input to HiDEM.
- page 11, line 9: Melt above the sea surface (?)
- page 11, line 11: 10x10 m2 grid
- page 11, line 12: is this new front modeled by HiDEM at each observational dates or only at the four selected ones? This should be mentioned.
- page 11, line 29: two days of computing time. (?)
- page 11, line 30: with HiDEM thereafter. When? Every observational times or only for t_0, t_2, t_4 and t_11?
- page 12, line 6: the no cie foot geometry should be indicated in Fig. 4.
- page 12, line 13: a rescaling of what? The sliding coefficient? Then this sentence seems to said exactly the opposite of the previous one? It has no influence but it speeds up...
- page 12, line 21: the next observed configuration.
- Caption Fig. 5: Basal friction coefficient obtained from inverse modelling
- Caption Fig. 9: there is no hashed red box. "The mean distance differences between the modelled and the observed front positive and negative" -> "The mean distance differences between the modelled and the observed front positions"
- Figure 10: You should indicate which model curves should be compared to observations? Which curves are expected to be superimposed?
- page 22, line 16: Remarkably is may be a bit exaggerated in light of Fig. 10?
- page 22, line 25: It is related to the rules used to estimate calving in HIDEM. An other rules could be that the block should not be grounded anymore?



Additional minor points by editor A. Vieli
p. 4 Fig 1: in figure (a) I really struggle to see the ‘for frontal positions’ mentioned in the caption. Make clearer
in caption of Fig 1, line 1: to me the bare rock seems rather ‘brown’ than ‘red’.

p. 5 fig 5: as mentioned above maybe integrate the HiDEM model in this schematic.

p. 6 line 3: I assume you refer to ‘sliding speed’ or ‘sliding coefficient’ here, ‘sliding’ alone seem rather vague.

P. 6 line 4: should in not say ‘iteration i to i+1’ instead of just ‘iteration i’.

p. 6 line 10: again again ‘the sliding…are taken’, …’sliding what?’, velocity….?

p. 7 line 18: replace ‘in reaction to’ with ‘for a’ as you would anly expect a reaction if cyou have a CHANGE in accumulation.

p. 7, line 21: ti would replace ‘sea level’ by ‘water line’

p. 7 line 22: ‘We call…’

p. 8 line 2: ‘…SUBMARINE melting during…’

p. 12 line 8: ‘…of the values further UP from the terminus…’

p. 16, Fig. 8a: caption: ‘Plan view of the OBSERVED frontal position

Dear D. Vallot and co-authors,
After having addressed most issues highlighted by the two initial critical but positive reviews (main points clarifications of methods, revise conclusion on control of basal sliding) rather well, they now also addressed the mostly minor points on the revised version from a re-review and the editor.
They did not fully restructure/refocus the paper towards a validation exercise as suggested in the rereview which I can accept (and should be left to the decision of the authors) but they added some clarification regarding this point (constraining modelling by observation) which are useful.
There are only very few minor technical points that should be addressed and are listed below.

Thus, after correction/addressing of these technical points the paper is ready to be accepted for final publication and I would like to thank them for their careful handling of the revision process.

Very minor technical points:

-Acknowledgments: I think it would be fair to achnowledge the reviewers in the acknowledgments for their input and help to improve the paper.

-p7 line 22 and p. 8 line 1: in this new section of text, again, you refer to ‘the basal sliding’ but it is not fully clear what is meant, ‘basal sliding velocity’ or basal friction coefficient’. Should be clarified.

-p11 line 34: ‘When simulating with…’, maybe better ‘For simulations with…’

-p18 line 3: ‘that resemble aN observed…’

-p23 line 14: ‘…and melt the subaqueous…’ (plural – links to plumeS)