Dear Dr. Gudaugsson,

Thank you for your submission to The Cryosphere. Both reviewers, as did I, found your paper interesting and novel, and in the main extremely well written. Both reviewers provided very thorough reviews and a number of prescient suggestions for improving the initial submission, and I thank you for taking these on board and resubmitting an improved draft that incorporates and addresses the reviewers' comments.

I have now given your rebuttal and revised paper my own thorough read-through, and from this I am content that you have addressed in detail, and by doing so added considerable value to the paper, the suggestions of both reviewers. I do not have substantive scientific comments to add (so my thanks to you and the two reviewers). I do, however, feel that there are a number of places where phrasing could be improved. I list these below and would appreciate you addressing these in a revised submission which I would expect to be ready to accept relatively quickly.

I also note that in your rebuttal you stated that the new figures are "temporary" and so before accepting the manuscript I would like some clarification as regards the final form of the new figures.

With best wishes, Rob B
(minor revisions follow)

P2 L13 vs. P4 L22 Decide on a consistent form of “full-Stokes.” I think the “f” is usually lowercase, and the hyphen is often used (though was not in the title of the Pattyn paper you reference), so the form in the previous sentence may be preferred.

P2 L18 Remove comma after “feature.”

P3 L2 Reverse “located” and “either”

P3 L7 “Either” only pertains to two cases. One alternative here is just to remove the word “either.” Or you could restructure to something like: “Subglacial lakes have been hypothesized to play a role in the initiation of fast flow in several possible ways. In some locations they may provide a steady stream of water downstream etc….”

P3 L17 Reorder “…capable of draining subglacial water effectively…”

P3 L16 Capital I and S for “Greenland Ice Sheet.”

P3 L19 Capital L “Lake Vostok” and add comma after “world.”

P3 L22 Add comma between “lakes” and “indicating;” remove comma after “episodically.”

P3 L30 I am not sure if you intend to use UK or US English. If the former, then spell as “metres” here. If using US English, keep this as “meters” but then change P3 L29 to “millimetres.”

P4 L2 Add a further comma between “active” and “lakes.”

P4 L14; P4 L22; P17 L21 (three cases) Where “ice-sheet” is used as a preposition, e.g. ice-sheet response, ice-sheet model, ice-sheet base, use hyphen in “ice-sheet.” Otherwise leave as “ice sheet.”

P6 L11 Reverse “correctly” and “reproducing.”

P6 L18 Add hyphens: “…water-content-dependent..”

P7 L1 Add hyphen “…pressure-dependent.”

P7 L4, and further cases on P14 L6 & P18 L4: Add hyphen “ice-streaming” (as ice-streaming is here used as a preposition in the case of “ice-streaming conditions”).

P7 L13 I think you should probably add an “s” to read “…periodic BCs for…” as you defined BC as a singular earlier in the paper.

P7 L14 This should read “…at both ends.” But perhaps it might be clearer if it read “at the upstream and downstream extremes.”

P7 L15: Replace “are” with “is”: “…symmetry for velocity and thermal insulation is imposed.”

P9 L1 Should read “To determine correctly…”

P9 L5 Strictly speaking you don’t need “or not” in this line, as that condition is implicit in your use of “whether.”

P9 L22-23: Rewrite: “…edges, where velocity gradients are large, and to resolve properly…”

P10 L2-4: The sentence as written is a little confused: I suggest a small rearrangement as follows: “The aim of the study is to show how the presence of a subglacial lake affects ice dynamics and thermal resolution, and to follow its effects on internal layering through…”

P10 L6 No comma needed after “momentum.”

P10 L7 Move comma, slightly rearrange: “…viscosity (n=3) unless otherwise stated explicitly, and all…”

P10 L25: “…to perturb isochrones layers considerably.”

P10 L29: You can’t use “both” for more than two cases. Just remove the word here and the meaning is fine. Bearing in mind the reviewer’s comment about the ambiguity of “a considerable distance” here too (and your response which addresses this by stating the factors that affect the considerable distance), I also think you still need to insert around here example values for what you mean by a considerable distance. This could be done with a small additional sentence that gives example values for the three cases in Table 2 (you stated in your rebuttal, for example, that this distance would be about 50 km for the medium lake).

P11 L7; P12 L15; P25 (caption Fig. 2); P28 (caption Fig. 4): If using UK English change to sp. “centre.” If using US English leave unchanged.

P10 L13: I think you could remove “, before the influence of the lake is felt.” I think it’s a little confusing/unnecessary.

P11 L15: For consistency with elsewhere, “streamlines” (no hyphen).

P11 L18 Reverse “at” and “both.”

P11 L27: Mild rewrite: “Increases in temperature, pressure and water content, and larger effective stress, all have the effect…”

P12 L13: Perhaps this could be just a little clearer if worded/punctuated as: “…and a pressure- and temperature-dependent viscosity…” In addition, although above you have clarified that elsewhere all experiments use nonlinear viscosity n =3, for further readability you could rearrange/add to this sentence as follows: “…lake size, made with a nonlinear viscosity (n = 3 in Glen’s flow law as used in our other experiments) versus a constant viscosity (nconst = 1014 Pa s) and a pressure- and temperature-dependent viscosity (n = 1) but otherwise using the same setup.”

P12 12 L15: “show” not “shows” (plural) and rearrange: “…profiles of horizontal velocity and viscosity over the centre of the lake for the three…”

P12 L19: You could choose to reinforce here why you now include this case, by additionally stating that the weaker contrast in basal traction inside and outside a lake might represent a lake beneath an ice stream.

P12 L26: Reverse “on” and “both.”

P13 L4: Replace “in” with “for.” “…for subglacial lakes in Antarctica…”

P13 L5-6: “…but refilling takes much longer.”

P13 L7: “lake diameter” or “lake’s diameter.”

P13 L17: Reverse “primarily” and “affected.”

P13 L21: Insert comma between “there” and “but.”

P14 L7: Add comma after “base.”

P14 L13: Insert “that was”: “…refreezing whatever microscopic water that was created upstream.”

P14 L17-18: “Firstly, draw-down…” “…ice sheet and, secondly, heat from…”

P14 L20: “…which removes heat more efficiently from…”

P14 L25: “…can lead away efficiently, and…”

P14 L27: Tense seems wrong here. Suggest “…until it completely refreezes.”

P15 L9: Remove “that” (it already exists earlier in the sentence). Also either replace “less” with “lower” or write out “…less lateral shear and lower longitudinal stresses...”

P15 L19: Capitalise Subglacial Lake Vostok.

P15 L20-24: Suggested rewrite: “Extrusion flow is not, however, a requirement for the formation of these dip and ridge features. To form them it is sufficient to have a sharp transition in sliding along with a negative downward gradient in ice viscosity. Our model further predicts that dips and ridges can form in situations where there is merely a strong decrease, not necessarily a complete disappearance, in basal traction.”

P15 L26-27: Suggest: “Subglacial-lake drainage cycles (including both draining and filling) can have frequencies…”

P16 L1: Replace “takes course during” with “occurs over.”

P16 L4: Insert comma after “respond.”

P16 L5: Reverse “partly” and “depend.”

P16 L29-30: Re-order: “On the other hand, drainage of large lakes… …filling times could be expected…”

P17 L3-4: At the moment this is not a sentence. Suggest: “In our simulated scenario of Fig. 6 the travelling-wave amplitudes of ~100 m would be well within the bounds of detectability with modern radar systems.”

P17 L5: Remove comma.

P17 L19: Reorder: “…eventually to disappear…”

P17 L23: Reverse “to” and “both.”

P17 L25: Insert comma after “which.”

P18 L2: Remove comma after “sliding.”

Figure 1: Can you clarify why you state in P9 L14 that the computational domain is 350 km by 100 km, but the results here are presented in plots 200 km by 90 km? You could also reinforce the caption by stating explicitly the along-flow and across-flow lake dimensions for the case presented here (as you did for the caption for Fig. 2, in fact).

Figure 2 caption: “inset” not “inlet” figure; & if using UK English change sp. “colour.”

Figure 3: I can see why caption b is presented along a subset of the model length, but it’s less clear why caption a isn’t presented across the full 350 km. Cases L and M still seem to be dropping towards the extremes, so is this worth showing?

Figure 6 caption : If using UK English sp. colour; sp. grey – otherwise leave unchanged.

Dear Dr. Gudlaugsson and co-authors,

I am delighted now to accept your paper for final publication in The Cryosphere. I thank you for presenting a submission that was of high interest to the reviewers and will hopefully now also be so for the wider readership of The Cryosphere. I thank the reviewers for their insightful comments, and yourselves for heeding these comments, and my editorial comments, with very clear rebuttal documents and revisions that have now made this a very readable contribution.

Best wishes,

Robert Bingham