Dear Authors,

The journal has received the reviews of the manuscript tc-2020-153 ""Non-normal flow rules affect fracture angles in sea ice viscous-plastic rheologies"
by Ringeisen et al. Based on the reviewers' comments and authors replies posted via the interactive discussion we recommend major revision of the manuscript. Please follow the recommendations from the editorial on the next steps for the revised manuscript upload. I attached the reviewers comments for your information.

Best wishes,

Yevgeny (on behalf of TCR)

Dear Mr. Ringeisen,
Thank you very much for your response and revisions to your paper. There are a couple of points I would like to ask the referees for further guidance on, and will expect another round of revisions after the second review.
With very best regards,
Jenny

Dear Damien and co-authors,

Thank you for your revision and response to reviewers. You will see that you did not respond adequately to all of the reviewers points. The requested changes are required to clarify your manuscript, and I fully agree with the reviewer on the need to present your assumptions and methodology clearly in the paper.

Some typos I found reading the paper are below. Please do a careful proof of the paper prior to resubmission.

Page 3, Line 62: "based on the grain size"
Page 6, line 160-161: Considering removing one 'only' from the sentence.
Figure 3: There is no orange arrow.

Best regards and looking forward to reading your revision,
Jenny

This paper is ready to publish in my opinion. I do have some specific technical corrections to consider.

Regarding your comment to the reviewer:
"Unfortunately, to our knowledge, there is no laboratory experiments looking at the deformation of sea ice with different confinement pressure."
Actually you point out yourself in your paper that there are laboratory experiments under different confinement ratios. "Laboratory experiments show this behavior and yield stresses in sea ice change above a critical confinement ratio (Golding et al., 2010; Schulson, 2002). " There have been triaxial tests done on sea ice samples. I point this out because the tone of your response might be construed as disrespectful to the valid point brought up by the reviewer.
Here is a list of papers documenting laboratory experiments on sea ice samples under tria-axial loading. There are two sets of experiments at lower confinements (Schulson's group) and higher strain-rates (Sammonds group).
Richter-Menge, J. A. (1986). Triaxial testing of first-year sea ice (Vol. 86, No. 16). US Army Corps of Engineers, Cold Regions Research & Engineering Laboratory.
Sammonds, P. R., Murrell, S. A. F., & Rist, M. A. (1998). Fracture of multiyear sea ice. Journal of Geophysical Research: Oceans, 103(C10), 21795-21815.
Sammonds, P. R., Murrell, S. A. F., & Rist, M. A. (1989). Fracture of multi-year sea ice under triaxial stresses: apparatus description and preliminary results.
Rist, M. A., & Murrell, S. A. F. (1994). Ice triaxial deformation and fracture. Journal of Glaciology, 40(135), 305-318.
Murrell, S. A. F., Sammonds, P. R., & Rist, M. A. (2012, December). Year Sea Ice Under Triaxial Loading. In Ice-Structure Interaction: IUTAM/IAHR Symposium St. John’s, Newfoundland Canada 1989 (p. 339). Springer Science & Business Media.
Murrell, S. A. F., Sammonds, P. R., & Rist, M. A. (1991). Strength and failure modes of pure ice and multi-year sea ice under triaxial loading. In Ice-Structure Interaction (pp. 339-361). Springer, Berlin, Heidelberg.
Gratz, E. T., & Schulson, E. M. (1997). Brittle failure of columnar saline ice under triaxial compression. Journal of Geophysical Research: Solid Earth, 102(B3), 5091-5107.
And finally an overview of the triaxial tests is available in
Derradji-Aouat, A. (2003). Multi-surface failure criterion for saline ice in the brittle regime. Cold regions science and technology, 36(1-3), 47-70.

The fact that Schulson's group is finding Coulombic behaviour under a variety of loading conditions probably backs up your point that the angle does not vary. However do note the very different behaviour under larger strain-rates.

line 102: "is a function" is repeated.

line 120: "So far, only the yield curve has been thought to affect the orientation of LKFs ". Just to clarify, Bill Hibler did know that the flow rule is important, he just did not explore the point in numerical experiments. I would rephrase this to be "So far, only the yield curve has been considered when investigating the orientation of LKFs in the viscous-plastic model."

line 405: Do you need the word "matter" between "granular" and "theory"?

I very much appreciate that you lay out a framework for how to design a rheological model for sea ice, and the metrics that should be used for calibration and validation on lines 486-496. Hopefully this concept gets traction within the sea ice dynamics modelling community.

Incidentally, you might want to check your use of fracture throughout the manuscript. Fracture envokes brittle failure, where as you are considering the shear zones that form in a granular (already broken) material. I admit that I have been very loose in using the term fracture in my previous work, and feel some misconceptions can result.

I would like to thank the reviewer Veronique Dansereau, who has greatly improved the accuracy and clarity of the writing in this paper. I thank both the reviewers and authors for working hard to write a clearer paper that hopefully will resolve missunderstandings readers may have.

Jenny