Arctic Thin Ice Detection Using AMSR2 and FY-3C MWRI Radiometer Data

Round 1

Reviewer 1 Report

The paper is devoted to thin ice detection using radiometer data.  The approach presented in the paper continues the previous study of the authors.  The paper is well-written and presents the procedure in detail. I have some minor comments:

11)      Could you please stress brighter what is different in the approach in this work compared to the previous study? What are the new steps?

22)      What are the gaps in the scale in figure 2? May be it is better to use colors from another color scheme.

33)      In figure 1, masks shown using negative values of ice thickness is better to be represented in another color scheme (greyscale for example).

 some typos:

In figure 5: cm is missed in X label

String 284: may be “from 0 to 1”

String 319: may be “interpolates”

String 555: may be “analysis”

English is good. Some typos should be corrected.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper addresses the issue of low accuracy in thin ice detection by developing a thin Arctic sea ice detection algorithm based on AMSR2 and FY-3C MWRI radiometer data. Experimental results show that this algorithm can improve the accuracy of thin ice detection, which is crucial for climate research and navigation in polar regions. However, some modifications are necessary before the paper is published, with specific suggestions as follows:

1. The authors review the development of the field in the literature review section of the paper, but this is limited to a description of the field. It is suggested that the authors could more comprehensively review the state of Arctic sea ice remote sensing research to highlight the contributions made by this study.

2. Some technical terms and abbreviations in the paper are not defined or explained when they first appear. It is suggested that the authors provide explanations when proprietary technical terms first appear to improve the readability of the paper.

3. The authors elaborate on the proposed detection algorithm in the paper, but some details are somewhat rough. For example, the criteria for selecting training and validation sets could be described in more detail; it is also suggested that the authors elaborate on the atmospheric correction method and its impact on thin ice detection.

4. The authors analyze the experimental results on two datasets in the paper. It is suggested that the authors describe the differences between different datasets in more detail, and how these differences affect the performance of the thin ice detection algorithm.

5. The authors explain and describe the charts in the paper, but for some charts, the authors only mention them without detailed elaboration. It is suggested that the authors provide detailed descriptions of all the charts in the paper.

6. The authors provide a brief summary of the paper in the conclusion section. It is suggested that the authors further discuss the broad impact of this research on Arctic sea ice monitoring and climate change research, and describe potential future research directions for this study.

7. The paper lacks some state-of-the-art papers in the field of sea ice research, and it is necessary for the authors to supplement them:
X. Sun, X. Zhang, W. Huang, Z. Han, X. Lyu and P. Ren, "Sea Ice Classification Using Mutually Guided Contexts," in IEEE Transactions on Geoscience and Remote Sensing, vol. 61, pp. 1-19, 2023, Art no. 4204019, doi: 10.1109/TGRS.2023.3268715.

H. Lyu, W. Huang, and M. Mahdianpari, “Eastern Arctic sea ice sensing:First results from the RADARSAT constellation mission data,” RemoteSens., vol. 14, no. 5, p. 1165, Feb. 2022.

Well.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Dear authors,

Thank you for an interesting manuscript.

The paper presents an improvement of the previously published ATIDA algorithm with an updated atmosphere correction scheme and addition of the application of the same procedure to radiometer data from the FY-3C mission.

The novelty of the study and contribution to the scientific community is found in the improvement of the results with new corrections and by extending the application to a new dataset.

The manuscript is generally well-written and presents a thorough and confined study. Improvements are suggested especially regarding the structure and method descriptions – in particular regarding section 2 along with a few minor text edits. A simplification of section 2, wherever possible, would improve the readability of the paper. A focus could be on including as little repetition as possible from the previous publication. This will help the reader to focus on the improvements and novelty of this particular study. Some suggestions are listed with the detailed comments below, for example division of section 2 into a section about data and another about the method improvements.

I recommend acceptance of the manuscript with major revisions; meaning that it might be worth to review changes in the method descriptions before publication. Besides that, it is an interesting manuscript with results that are valuable for e.g. supplementary data for thin sea ice areas of other products and directly applicable for navigation purposes.

Detailed comments listed by line numbers are given below (“->” means “change to”):

Line 48: -> liquid water and water vapor content

Line 57-62: Perhaps define here how the difference between FYI and thin ice is defined and used in these studies

Line 66-69: Contains some repetition of the section above.

Line 74: -> , is an improved version…

Line 82: perhaps specify criteria for “more dependable”

Line 93: -> mixing of its TB signatures…

Line 95: -> Such mixing can for example make…

Line 104: -> , and determine an ATIDA2-like…

Line 117: -> , the updated charts can…

Line 119: I would suggest to separate section 2 into two; one about the “Datasets” and another about the “Method” or “Method improvements”

Line 128: Perhaps expand a little here, like: “… only when the air temperature, Ta, according the ERA5 reanalysis data, is below minus 5 degrees” (Remember to specify all parameters used like Ta, Tam, …and abbreviations e.g. NWP)

Line 166: “10 km (30 km) grid size” might need a bit more explanation here. It is obvious later but confusion here.

Line 178: -> is one of China’s…

Line 185-186: Perhaps add a reference to the data product here.

Line 205: Start the “Methods” section here

Line 210: Explain T’s (Bnwp and Bref) for completeness

Line 213: Explain NWP

Line 216: -> It was found that EAR5

Line 218: -> at low SIC values. In our earlier study in [13] the LW-correction was…

Line 227-241: Can this part be simplified or clarified. Here I find it difficult to follow all arguments.

Line 234: -> to use a daily…

Line 240-241: Perhaps move this to beginning of next section

Line 245: Formula (4); I would suggest to use another name for the coefficients than Tmix as it does not refer to a temperature (alpha mix could be a suggestion)

Line 254-265: Also here, I find it difficult to follow the text – please clarify or simplify.

Line 271: Figure 3; the colours are almost the same for OSISAF and Mathew effective temperature lines.

Line 288-303: Could a block-diagram explain the main parts of this? Or, describe only how your approach differs from others or your own previous work.

Line 331: -> 30 km were integrated…

Line 334-350: Could the most important numbers, described in this part, be summarised in a table?

Line 351: This section is much easier to read than sections 2.5-2.8. and describes well the novelty of the study.

Line 387: Please explain LDA subscript s

Line 404: -> it is a requisite…

Line 417: Could you elaborate more about how this study takes this issue into account? Either here or in the discussions later.

Line 466: For consistency also add type Ib error or note that it is not important

Line 481: What is T subscript am?

Line 485: -> errors and Tam indicates

Line 519: Figure 4; perhaps move (a)-(d) to the subfigures as they are closer to the subfigure below that the rights ones.

Line 595: Perhaps replace “sufficient” with “similar”

Line 633: For completeness explain “TIR”

Line 634: -> However, in here, estimation of…

Only minor revisions are needed - see detailed comments above.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Dear Authors,

Thank you for the revised manuscript. I acknowledge that most of my comments are considered and have no further requirements or suggestions before publication.