Dear Nicole Clerx and co-authors,

Your manuscript has now received two detailed peer reviews that highlight the strengths and shortcomings of the manuscript. The reviews were constructive and generally quite supportive of your work. They each identified specific issues that would need to be addressed in a revised version of the manuscript in order for potential future publication in The Cryosphere.

Thank you for your Author Comment responses to these reviews. I find your responses, proposed changes, and already modified drafts of figures to be promising. As you no doubt noted while preparing your responses, both reviewers find issue with the three-order-of-magnitude difference between modeled and measured lateral flow rates and encourage you to enhance the discussion around this apparent discrepancy. I believe this will be an important component of your revision and eventual contribution to the firn literature.

Thank you for your detailed responses to the referees and plans for revision. I look forward to seeing the revised manuscript.

Cheers,
Kristin Poinar

Dear Nicole Clerx and co-authors,

Thank you for your revised manuscript and thoughtful response to both reviewers' comments. The manuscript has now been reviewed again by both reviewers, who note its improvement. The reviewers now identify a number of smaller points that must be addressed before publication in The Cryosphere. Please take another round of revisions with the same careful consideration of each point you executed in the first round.

Cheers,
Kristin Poinar

Dear Nicole Clerx and co-authors,

Thank you for your response to reviewers and corresponding revisions to your manuscript. I find it nearly ready to go, but I have a few suggestions to better incorporate the insights of Reviewer #1 to your manuscript. Given the state of our understanding and capability of observing meltwater flow through firn, I judge that the caveats pointed out by Reviewer #1 give valuable context to your measurements and findings, and should be incorporated into the manuscript itself (briefly is fine), rather than addressed solely in the review files, which will be publicly available but relatively buried to readers.

All of the line numbers below refer to the differenced version of your manuscript (ATC2).

A. line 253 "could be a lot higher" -- please provide an estimate (a rough estimate is okay) in place of "a lot".

B. line 335 -- Reviewer 1 commented that the timing is biased low, as the authors used time of first arrival, rather than time of peak concentration through. In their response, the authors pointed out that they did not measure concentrations (it was not possible with the methods/equipment they had), so the peak time could not be discerned. Nevertheless, the authors should comment on this timing bias —- it means their velocities are biased high. Comment here or in the discussion how this compounds or offsets other sources of error.

C. Reviewer 1 points out that the datum for the water table is the ice slab surface, which can undulate locally and is not likely to be level or even flat. The authors should comment on this -- probably in the discussion (lines 466-7), or alternately lines 307-8, where the water table measurement method is described, or lines 386-8. Because the authors are concluding no correlation between the local water table height and lateral flow velocity (stated on line 466), these undulations may well matter, and should be addressed.

D. Table 2 - unsaturated has no quotes, while 'saturated' has quotes. Why? Suggest to choose a style and apply to both for consistency.


With the above additions, I will be happy to see this work in The Cryosphere. I believe it will be a worthy contribution to the community's ongoing effort in the important problem to better quantify meltwater flow through firn. Thank you again for your work and attention to addressing the reviewers' comments.

Cheers,
Kristin Poinar

Thank you for the edits. I am now pleased to accept this manuscript for publication in TC. Congratulations on your new contribution to the field and literature!