Dear authors,

Many thanks for posting your answers to the two referees that reviewed the manuscript.

As far as I can see, the only critical point raised by the reviewers (and particularly by Reviewer #1) is the discussion of the accuracy of the final bedrock topography, i.e. an assessment of the actual added value provided by the gravity measurements. Paraphrasing, the reviewer’s first and third comment ask for a quantification of the accuracy of the final result, or better, a metric quantifying the impact (in terms of accuracy) that the use of gravity measurements has.
I think that this point is important, also because your main text stresses the fact that such an improvement is actually happening (e.g. second-to-last sentence in both your abstract and the introduction). At the moment, one might argue that this improvement is postulated, rather than shown.

I understand the difficulty in “showing” such an improvement, especially since reliable ground-truth information is difficult to obtain. However, I have the impression that the original GPR/RES data (i.e. the one by Downdeswell et al., 1986 [https://doi.org/10.3189/S0260305500001130], rather than the interpolated ones by Dunse et al., 2011) might be of help. Whilst I’m not sure how feasible it will be to reconstruct distributed reliability information for that data, I imagine that at least the information about the spatial distribution of the data (the interpreted dataset is available through the Glacier Thickness Database: https://www.gtn-g.ch/data_catalogue_glathida/) can be very useful in strengthening your discussion on the matter.

The remaining points raised by the reviewer’s seem more straight-forward to handle, as your answers show. Reviewer #2 also comments on the importance of the geological interpretation, noticing, however, that a geologist more familiar with the region should provide his/her advice on it.
In light of the above, I don’t see major obstacles for a final publication. However, I think it is appropriate having the amended version of your article seen again by an external referee (TC’s system calls this a “major revision” which might sound unduly “harsh” in your case).

In this sense, I would like to ask you for such a new manuscript version to be produced and posted, so that the review of the amended version can happen.

Many thanks for your collaboration and best wishes.
Daniel Farinotti

Dear Authors,

I am pleased to say that after having received a re-review of your submission, your manuscript is close to publication in The Cryosphere.

Before this happens, however, I would like you to consider the technical corrections highlighted in the enclosed, annotated version of the manuscript. All corrections should be reasonably straight forward to implement.

Many thanks for having adequately taken into consideration the comments of the former reviewers, and please accept once again my apologies for the very slow process.

Best wishes
Daniel Farinotti