Dear Peng Lu,

Thank you very much for your detailed response to the reviewers comments. There are still some concerns that need to be addressed before this paper is suitable for publication in The Cryosphere. Please consider the further comments of reviewer 1. Importantly, the paper could benefit from professional English proof reading.

I would like to see more clarity in your argument that pond color is related to ice thickness beneath the pond. In particular you have no quantitative discussion on the dependence of this relationship on your assumptions for optical properties of the ice

Abstract: Note the comments from reviewer 1. If pond color is not related to Hi, you can not claim this here. Further in the manunscript you identify that the relationship is only true for ice thinner than 1m. This is important to include in the abstract, if it is indeed true.

Page 1 line 9: Capitalize 'using'
Please check your grammer throughout.

Page 1, line 25: " lower the surface albedo from as high as 0.8 (snow) to as low as 0.15" strange grammer. rephrase.

" As a result, melt ponds are an issue as important and inevitable as the dramatic decay of current Arctic
sea ice". I don't understand this. Melt ponds are not the issue. You need to rephrase this sentance, or change it for something that makes sense.

page 2, line 28: clarify what are trapped ponds?

page 3: " Efforts will also be made to find ways to use the information provided
by pond color more effectively because this color contains the optical response of melt ponds and sea ice to incident solar
radiation. " an example of a sentance that needs work. First of all, do you want to use the future tense here, perhaps more specifically state "in this paper" and the sentance is convoluted. It is not easy to understand.

page 4, line 20: again check grammer, remove "and".
Please get some professional help in correcting your english.

page 5, title for section 2.2. From which spectrum? clarify. Perhaps 'observed spectrum'?

page 5: Illuminance Y, and the Y coordinate can be confused. Please consider using different symbols.

page 7, line 9: "... meltpond
albedo is sensitive to Hi for thin ice, but to Hp for thick ice, ..." This sentance does not make sense, is one property (Hi,Hp) sensitive and the other is not?


page 10, line 15: "The agreement is acceptable". In order to make this statement you need to know the sensitivity of hue, saturation and luminance to sky conditions and ice optical properties. I see that you have numerical experiments considering both optical properties of the ice and solar zenith angle, so I expect you can provide some numbers for the sensitivity so we can believe your statement. It is not possible to determine this sensitivity from the manuscript because you only provide a plot (figure 7) of the sensitivity of pond color to optical properties for 1m ice. I need to be able to see that the sensitivity to ice optical properties does not larger than the variation shown in figure that will allow depth to be estimated to a reasonable tolerance for the result to be meaningful. In figure 7 the range of scattering coefficient results in pond colors that are over a larger range than the observations shown in figure 4. What is a reasonable range for the uncertainty in scattering, and how does this impact the results presented in figure 4. (And the same question for other parameters in the model).

page 11, line 11: I do not think "Besides" should be hear. The ice scattering and the water scattering are seperate from each other in the context of this discussion.

page 14, line 10: "The result is acceptable because of the very few available data here". Few data points is rarely a reason for a result to be acceptable! There is correlation between the data sets, I would just state the facts and leave out subjective sentances like this one.

page 14, line 13: "The results give support for a possible new waymethod of determining the sea-ice thickness, especially for melting sea ice," In order for this to be true the method needs to have sufficient fidelity to provide meaningful thickness estimates. i.e. what is the resolution of thickness, for thin ice below 1m thick, that could be resolved with the method? Is this resolution a function of thickness, lighting conditions?

page 16, line 10-15. Very long sentance. Break up in to a least two sentances.

page 16, line 17-18: "As the first insight into the color of melt ponds, we tend
to pose a possibility instead of draw a conclusion because of the limited available observations so far". "tend to pose" is vague and makes the reader think you are not clear on the future direction. I recommend you rephrase this sentance.

Please ensure your figure numbering is correct in the text in relation to the changed figure numbers? I am not sure figure 9 is referred to correctly. Do you have significance and correlation values for both figures 9 and 10? Are you actually improving correlation by taking the small subset of data with Hi < 1m?

Figures are missing panel labels. Please place (a), (b) etc appropriately.


If you need any clarification on these comments, please do not hesitate to contact me to set up a time to talk by phone.
Very best regards,
Jenny

Dear Drs. Lu, Lepparanta, Cheng, Li, Istomina and Heygster,

Thank you very much for your detailed and considered response to my comments and the reviewers comments.

I disagree that a variation in pond color of 0.08 due to the range in possible absorption coefficient, can be ignored. This signal is about 50% of the pond color sensitivity to pond depth or ice thickness. So it is significant. Or am I missinterpreting your figure captions for S1-S3 and figure 4? It is not clear to me if you are plotting a relative error in all cases, the absolute error (which is my assumption in the statement above) or the anomaly between each sensitivity experiment and the experiment shown in figure 4. You need to clarify what 'Variations of melt-pond color' is, and how you are comparing between the supplimental figures S1-3 and figure 4 (an anomaly or relative difference?).

You are perhaps correct that error in absorption does not change the general relationship for particular ice types, though there may be more impact as the ice properties change when it thins or becomes rotten at the pond base. Thank you for adding bars on figure 9. Thank you for making the effort to demonstrate the sensitivity. I am trusting you that the ranges you choose for the parameters in the sensitivity study are the ranges of uncertainty for these.

Line 26 page 10: changing and variables. These two mean the same thing. You can just say 'variables' in the calculation.

While you are considering minor revisions, please do take the opportunity for one last proof read to ensure your language is precise.

Best regards,
Jenny

Dear Dr. Lu and coauthors,
Thank you for your detailed reply to my questions clarifying how you performed the uncertainty estimation. In my opinion this manuscript is acceptable for publication.
Very best regards, it has been a pleasure working with you,
Jenny