Dear Dr. Pope,

Thank you for your submission to The Cryosphere. Both reviewers found your paper interesting, valuable, and worth publishing subject to your consideration of some relatively minor suggestions they posted in their reviews on the TCD website. I am pleased that you have taken these comments on board in your revised submission.

Following the above process, I have given the paper my own read-through, and from this there remain a number of minor issues I would like you to address, after which I expect the paper to be suitable for publication. These are listed below. In addressing these, it would be useful if you could return a rebuttal document that includes my list of suggestions, and your agreement/rebuttal, point-by-point, together with a tracked-changes document as before.

With best wishes, Rob B
(revisions follow)

Throughout the manuscript: One instance of "bi-naming" Sermeq Kujalleq / Jakobshavn Isbrae is fine, but unnecessary for every single instance of the name in the manuscript.

Throughout the manuscript: Using search/replace, have a thorough look through the manuscript for where you use Landsat / OLI or both terms. One you have explained the association once (in the introduction) - or possibly also in the abstract and conclusions - elsewhere you should just use one term. I'd stick to OLI.

P2 L5-6: Delete “as OLI”.

P2, L10: Better to clarify “supraglacial” before “lakes”?

P2, L14: Replace “are” with “also”.

P2, L19: Improved English would have “both” and “for” reversed here.

P2, L21: Better to insert the reference at end of sentence after “Greenland”.

P2, L27: Insert “DigitalGlobe’s” before “WorldView” (…then you don’t need DigitalGlobe again on
P8 L4).

P2, L28: Capital V for WorldView; Insert comma after WorldView-3.

P2, L29: Insert commas before and after phrase “such as streams”.

P3, L12: Rewrite: “and that minor variations in effects of atmospheric path radiance can be ignored.”

P3, L14: Is it really necessary to include the word “successful,” or even to include the references you included here to make this point? Seems possible to rephrase: “Landsat 8, launched in 2013, hosts a new multispectral sensor, named the Operation Land Imager (OLI), suitable for lake-depth estimation. The OLI has enhanced…” [then continue into existing sentence commencing L14-15]

P3, L19: Insert commas before and after phrase “and narrower multispectral and panchromatic bands relative to ETM+”.

P3, L20: Remove comma before “respectively”.

P3, Paragraphs 2 and 3. Paragraph 3 opens with the statement “we investigate refinements on retrieval methods…using Landsat 8”. The inclusion of “refinements on” to this sentence is a little awkward, and it suggests that previous work has already used OLI to estimate supraglacial lake depths. If so, are these previous studies specifically those referred to in L17 that “largely used red and green wavelengths”…? I think what is missing here is clarity on exactly what are the “published studies” referred to in L17 (i.e. are these specifically w.r.t. Landsat 8 OLI?). Depending on your answer to that, for L24-25, would it then be equally valid simply to write: “In this paper we investigate retrieval methods for supraglacial lake depth from Landsat 8 imagery” (i.e. dropping the “refinements on”?).

P4, L10: “both in Greenland and Antarctica”.

P4,L9-14: I suggest a mild revision here for clarity: “Based upon a description of the processes that take place as light enters, passes through, and exits a lake, the method has been used successfully in Greenland and Antarctica (e.g., Sneed and Hamilton, 2007; Banwell et al., 2014). Being physically-based it is easy to adjust if measurements of lake water and lake bed properties are available. However, it assumes…” [then into sentence continuing L14]

P5, L1-11: Just to note something strange happened with the editing tools in this section, so that it appears you intended to delete some lines – but I don’t believe this is your intention from your rebuttal comments. In your returned manuscript just have a check of what you definitely want to include.

P5, L23-26: The sentence as written doesn’t work. Should “has been used” be deleted from L23? Is “also” necessary in L25? Greenland Ice Sheet should be written with capital I and S, as in this case is used as a proper noun.

Section 2.2: You don’t seem to decide whether to term the method the “spectral band ratio method”, just the “band ratio method” or the empirical method. I suggest you change instances of “band ratio” to “spectral-band ratio” (P5, L27; P6, L1) and change “empirical/band ratio” to just “empirical” on P6 L5.

P6, L17: What is the current status of Pope, in review? Better not to reference work in review if publication not guaranteed.

P6, L11-21: Suggested rewrite: “In summer 2010, coincident lake-bottom reflectance and depth were acquired over a supraglacial lake in West Greenland using a small remote-controlled boat equipped with a compact spectroradiometer and a small sonar (Tedesco et al., 2011; 2015)”. (In the sentence as written the referencing practice was strange; I don’t think it’s actually required to repeat the term "in situ" beyond the section title; and I think it would be good just to underscore that it’s a supraglacial lake under consideration here).

P7, L10: “we do not” for consistency with present tense used elsewhere.

P8, L4: Despite the reviewer query, if you wish to use 0.5 m pixel-1 here (with -1 superscript), I find that acceptable, even preferable.

P8, L4: Remove “DigitalGlobe’s” here (more logical to put this, if needed, on p2 as advised above).

P8, L12: Should “90%” come before “horizontal”?

P8, L22: Insert comma after “Greenland”.

P9, L1: Despite reviewer comment, “blunders” sounds informal to me. I would maintain this as “errors”.

P10, L9: rearrange “still to perform”.

P10, L5-26: Why do you need to add the day-of-year number after each date? I don’t see you using these day numbers in any of the figures, so is there any other cross-referencing requirement?

P10, L28: I think a rewritten sentence, with just some minor elements of reinforcing data sources/locations, might just convey the link better here: “For both of our case study regions, northwest and southwest Greenland, we difference all overlapping areas of OLI-derived lake depths and WorldView-derived DEMs.”
P10, L30: Replace “methods” with “results”.

P11, L24: I think “time series” is two words…

P12, L3-4: Insert commas before and after “which transects the lower Sermeq Kujalleq (Jakobshavn Isbrae)” and reverse “both of” in L4.

P12,L6: Pretty sure you mean “latitude”, not “altitude” here.

P12, L19-20. The sentence is ambiguously written to implicate slow flow in less available meltwater. Suggest: “At higher elevations, slow flow leads to low-amplitude ice surface topography thus shallower depressions, and there is also less available meltwater to fill ice-surface depressions.”

P13, L10: What is the status of the Moussavi et al. paper?

P13,L16: Remove “Nevertheless”. It suggests possible disagreement with a previously stated point, but here you’re not really doing that.

P13, L20: Rewrite: “…laboratory-measured g with that derived from…”

P13, L21: Replace “the one” with “that”.

P13, L31: Remove “value”. The use of value/values in association with g continues to occur in the paper. Please search for and remove for the whole paper, as it is sufficient to use g.

P14, L6: “Depth” not “Depths”?

P14, L7: compare results “with”, not “to”?

P14, L7: Should be “apply” not “applied” to keep writing in present tense, as elsewhere…

P15, L2: Remove one instance of “used” from this sentence. Also, the sentence warrants some references.

P16, L8: “…common both in…”

Section 5.4: I am rather unconvinced of the worth of this section. It does not make much use of the results generated by the paper itself other than emphasising the potentially short duration of lakewater residence times. Apart from that it seems mostly to be rationale-for-study, which seems out of place this late in the paper. In my view, in its brevity it also rather oversimplifies the hydrological system, and only presents the case for how supraglacial lakes may enhance ice dynamics by enabling episodic injections of floodwater to the ice base, and/or increase heat transfer to the bed. The second process can only be a secondary effect, while there is some counter evidence to the former in the literature, especially if one is considering the degree to which supraglacial melt inputs affect ice dynamics over annual timescales, i.e. the timescales that really matter when trying to determine if melt increases may accelerate Greenland’s dynamic response.
I think you already did a nice, concise job in the very first paragraph of the paper of saying why studying supraglacial lakes is important, and I would recommend your paper would stand very well without this final section to the discussion.

P17, L13: Suggest you expand OLI to full name for its first mention in the conclusions, as some readers may have skipped to here pretty quickly and need the reminder/introduction to the abbreviation.

Figure 1 caption: As you have the Howat et al. (2014) reference, you don’t need “courtesy BPRC Glacier Dynamics Research Group, Ohio State University” in the final line.

Figure 2: The caption for part (a) suggest part (a) should pertain to ETM+ but it appears (at least from the annotation in the top right) to pertain to OLI. The reverse issue is true for part (b) and the caption for part (b). Unless I missed something about what these figures are showing, there seems to be a little mix-up. I do think the annotations are good in principle though, so can similar text annotations for OLI-C and OLI-G be added to parts (c) and (d)?

Figure 3: Somewhere in the caption or legend it would be nice just to have the clarification that the bands are “Landsat 8 OLI” bands. Just for the reader who may jump straight to diagrams.

Figure 4 caption, L10: use hyphenation throughout “in-situ-regressed”.

Figure 4 label y axis: Capital D for both instances of “Derived”

Figure 5: Requires a clarification in the caption as to what the small text annotations associated with each line refer. Presumably path/row number from WRS-2/Irons et al., 2012 – but this needs to be written explicitly into the caption.

Figure 6: Re the sentence “A histogram of lake depths (a) shows many shallow lakes, many lakes reaching depths of ~3 m, and a maximum lake 6 depth of ~6 m”. What is shallow? Why identify 3 m on this curve in particular? I think the only valid part of this sentence is the identification of maximum lake depth – but even if all statements were valid, the sentence is anyway unnecessary for a figure caption as readers should get the information they desire simply by looking at the graph itself. I would rewrite this whole sentence simply as “(a) Histogram of lake depths”. Your caption to part (b) is also strangely composed. I suggest rewriting as “(b) Lake-depth by pixel distribution.”
Finally, re this caption, I can’t follow what is meant by the reference to hypsometry/GIMP DEM. Can you clarify?

Dear Dr. Pope and co-authors,

It is my pleasure now to accept your manuscript "Estimating supraglacial lake depth in western Greenland using Landsat 8 and comparison with other multispectral methods."

Many thanks for submitting this interesting and very relevant work to TC. I would also like to thank you for very clear response documents and engagement at all stages of the review process.

Very best wishes,

Robert Bingham