Dear Alexander Geigiuc and co-authors,

Thank you for your response to the reviewers, which has greatly improved the paper. I have some comments that I hope you can address. These are mostly related to readability and explaining the interest of your results for the general readership of The Cryosphere.

Please have an English speaker proof read the paper. Some examples of gramatical errors are provided below. Line numbers refer to the manuscript with marked up edits.

page 1, line 3: "daily in manually prepared ice charts"

page 1, line 6: "of the degree of ice ridging"

page 1, line9: either "using the Random Forest classification method" or "using Random Forest classification".

page 1, line 14: Consider rephrasing. Is the word "studied" appropriate here. Perhaps clearer to say "The correspondence between the degree of ridging in ice charts and the actual ridge density was validated with data collected during and field campaign in March 2011". I removed "extensive" because this is a word that places a judgemental value on the work, without providing context. I think it is personal choice if you want to keep "extensive".

page 2, line 2: a comma in front of "which"

page 2, line 11: comma needed before "the expertise"

page 2, first paragraph: Perhaps it would help the reader to identify why you talk about particular features, such as salinity, in the context of making ice charts. I think you only need a sentance in the paragraph explaining that the parameters you describe affect interpretation of remotely sensed data in classification of ice type.

page 2, line 27: Not usual to start a sentance with "Because". This sentance needs to be rephrased also.

page 2, line 29: remove "th"

page 2, line 33: "certian amounts of"
The last sentance of this paragraph is overly complicated. Simplify if possible.

page 3, line 6 & 7: Reconsider if "to" is appropriate in this sentance in two locations.

page 3, line 11: again "to" not needed here.

page 3, line 10 to end of section: Perhaps a subsection is appropriate for this detailed information, in section 2.1? With line 9 being the end of the introduction. It is traditional for the paragraph at the end of the introduction to be a map for reading the paper.


page 4, line 13: missing space "13 was".

page 4, line 15: "weather remained similar"

page 4, line 19: "The 15th of March ice extent reached"

page 4, line 21: consider using the word "further" rather than "any more".

page 5, line 2: "means" not an appropriate word here. A period can not mean! "the test period includes the 13 SAR mosaics"

page 5, line 17: Specify that the -28db floor is nadir (is this correct?)

page 5, line 32: check italicisation of "where".

page 6, line 6 and elsewhere: remove space in front of '.'

page 6, line 7: "in the resolution" -> "at the resolution"

page 6, line 15: rephrase " DIR 5 indicades brash ice ..... " I am not sure what you mean by "barrier" and while is not an appropriate conjuction to use in this sentance.

It would be very helpful to discuss here what a DIR of 2, 3 and 4 actually means. How are the catagories discriminated?

page 6, line 26: Something is missing in front of "does not make any sense". Or just delete these words.

page 6, line 29: "also" not needed in this sentance. I am not sure what this is "also" to!

page 7, line 17: Is there any affect of water pockets in the ridge on decreasing keel depth estimates? I think there was some work by Stefan Hendriks attempting to model this phenomena. Asking you check for completeness, and to provide the most up-to-date understanding of the accuracy of ridge measurements with HEM.

page 7, line 17-18. This sentance is a little awkward. How about: "Mid-basin in the Bay of Bothnia, the level ice thickness reached 60 cm with somewhat decreased ridging compared to the average winter with similar wind conditions."

page 7, line 24: "surface profiles"

page 7, line 25: "with the Rayleigh criterion"

page 7, line 29: Might be clearer if you write out "per kilometer".

Regarding the lidar data collected in previous years: Is this data collected in similar locations and ice type classifications from year to year? Where the field campaigns at the same time of year?

page 8, line 7: "To the densities ....". Rephrase this sentance. "The densities are mostly affected by the windiness of the season ...." What do you mean by windiness? How do you quantify this?

page 8, line 15: It is not easy on the reader to say "0.2 m above cutoff". Perhaps state "the average sail height, for sails above 0.4m, is 0.6m in the Bay of Bothnia."

page 9, line 9: "typically consisting of optical sensors". You do not need two "or" in this sentance.

page 9, line 11: I don't think you need to mention DIR 5 here, as it was introduced earlier and their you can mention it is not included in the analysis.

page 9, line 11: "does not" -> "do not"

page 9, line 13: Does disregarding ice charts that do not agree with coincident SAR analysis bias your study? Where you always sure that the disagreement was due to different information going into the manual analysis? Please clarify that you are only rejecting data for which you have evidence that the manual classification is wrong.

page 9, line 25: "there were still a few cases"

page 9, line 26: "These differences .... ". This sentance is awkward. Rephrase.

page 9, line 32: "over the Bay of Bothnia"

page 10, top paragraph: Can you comment on whether it was the aquistion of visual observations, for example, that improved the DIR classification in these two examples? Also, proof read this paragraph for awkward grammar.

page 10, line 19-20: What is a feature vector? Either state this is described later, or briefly explain.

page 10, line 35: should there be an "and" rather than a semicolon between the citations?

page 11, line 2: "The Markov Random Field (MRF) approach ..."

page 11, line 19: "algorithm", one too many ifs

page 11, line 24: remove "the" from "the Fig. 4".

page 11, section 3.2, first paragraph: It is unclear what "SAR features" are when they are first mentioned. Perhaps you can say "Twelve features are extracted for each segment from the SAR backscatter data. These are refered to as SAR features from here on."

page 14, line 8: "which fragments we assume" -> "which we assume"

page 14, line 10: Kurtosis repeated. Remove one.

page 14, line 13: "In Fig. 5"

page 14, line 17: " we found that", remove "out"

page 14, line 21: is "also" needed here?

page 14, line 28: "and the notations used in this algorithm"

page 15, line 26: "prevents the same features from dominating every tree"

page 16, table at top, item 1(b): "to the bootstrapped data" should "to" be "with"?

page 16, line 21: "from the computed 13 features introduced in Section 3.2."

page 17, line 34: "In summary ..."

page 17, line 35: missing "and" before "iii)".

page 19, line 28: "We concentrated our analysis on the areas ..."

page 19, line 29: "... can impact the backscattering statistics ..."

page 21, line 32: " Data of all three months ..."

page 21, line 18: " In none of the months was DIR 2 successfully detected due ..."

page 21, line 22: "were usually identified except". "well found" is non-sensical.

Check that the figures are referenced in order. I think fig. 12 is discussed before fig. 11 for example.

page 21: Can you comment on the fact that the autonomous algorithm missclassifies ice edges from cracks and leads and ridges. Or am I missinterpreting this?

page 22, line 22: "... better segmentation accuracy ..."

page 23, line 29: what is "importance value". I think this statement is suffering from gramatical problems.

Check the order Tables are addressed in the text. I think Table 1 is first mentioned after tables 2 and 3, on page 23.

page 23, line 5: remove the from "the feature reduction"

page 23, line 7: "In none of the cases did the classification accuracy improve ...."

page 23, line 8: ".... decreased by just a few ..."

page 24, line 17: "... a smaller DIR value is often assigned ..."

page 24, line 19: "This is especially true for DIR 2."

page 24, line 20: Surely it is a problem for automatically generated charts that SAR imagery might not have been provided to the FIS in time for daily charts to be produced? Rephrase the last sentance in this paragraph, it is a littel awkward.

page 24, line 23/24: "from the easier navagatable ones"

page 24, line 24: "... relies on SAR image ..."

Based on your finding of the incosistency in classifying DIR 2, would you say this is a useful classification band to keep in the DIR scheme?

page 24, line 31: "between ridged areas" ???

page 25, line 33: "The area of level ice always exceeded ..."

page 25, line 20: "seams" is a very subjective word to use here. It is also used twice in the same sentence.

Can tables 3-7 be combined into a single table? Prehaps with multiple panels?

Figure 3 caption: degree of ice ridging is capatalised throughout the manuscript text.


The readership of The Cryosphere is more general than this articles intended audience. I believe that the analysis you have presented in useful for extracting information about surface roughness from SAR C-band imagery. As such your article may be of wider interest than the operational ice charting community. Would you be able to provide some additional context in the introduction and/or conclusion sections to demonstrate the wider applicability of your results? For example, can your methods be extended to investigate changes in surface roughtness, ridging throughout the Arctic? Are there any impediments to this?

Finally, while you state that the method could be applied to the Arctic Ocean as a whole, how do you know that your methodology is not dependent on the relatively fresh and thin (therefore smaller block size in ridges) nature of the ice in the Baltic? Can the method identify weathered ridges that have survived a summer? I agree that the methodology will be useful for other ice services to impliment, in seasonal ice zones. I would like the paper to be more accessible to the general readership of the cryosphere who may be interested in variability of ridging in the seasonal ice zone.

Thank you for your contribution and I am looking forward to your revisions,
Jenny

Dear Alexander Geigiuc and co-authors,

Thank you very much for the clarification you provided in your response.

Below are a couple of responses to specific points. I have chosen "Publish subject to technical corrections" in case you would like to clarify these two points in the manuscript.


page 5, line 17: Specify that the -28db floor is nadir (is this correct?)
The specified value (noise floor) is not and cannot be for nadir, since
the SAR antenna does not measure at nadir. The specified nominal
value for noise floor, is applicable for the whole incidence angle range,
according to the SAR specifications.

- Thank you very much for the clarification. Please could you consider clarifying this in the text, to help the casual reader.


page 21: Can you comment on the fact that the autonomous algorithm missclassifies
ice edges from cracks and leads and ridges. Or am I missinterpreting
this?
Ice edges are identified using the sea ice concentration information.
We have not noticed any particular problems in their classification.
E.g. if leads and cracks are large enough, then they form segments
of their own which were usually well detected. It may be that we did
not understood well the point in your question.

- What I was trying to express here is a question of whether lead, or floe, edges affect the ridge interpretation. I think this might be a technicality that came to mind as I was reading the manuscript. I now understand that ice edges are much larger features that what I was considering to be an edge (the floe edge). Typically the ice edge is not the edge of regions or large leads. Perhaps consider defining what you mean by an ‘edge’ in your detection. I think the first time you mention this is page 2, line 34 in the unmarked up manuscript. I am also unsure how “edge pixels” are classified (page 11). I think this is where my confusion arose from.

Sincerely,
Jenny