Monitoring Arctic thin ice: a comparison between CryoSat-2  SAR altimetry data and MODIS thermal-infrared imagery

Müller, Felix L.; Paul, Stephan; Hendricks, Stefan; Dettmering, Denise

doi:https://doi.org/10.5194/tc-17-809-2023

Articles | Volume 17, issue 2

https://doi.org/10.5194/tc-17-809-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-17-809-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 17, issue 2

Research article

|

17 Feb 2023

Research article |

| 17 Feb 2023

Monitoring Arctic thin ice: a comparison between CryoSat-2 SAR altimetry data and MODIS thermal-infrared imagery

Felix L. Müller, Stephan Paul, Stefan Hendricks, and Denise Dettmering

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Final revised paper (published on 17 Feb 2023)
Preprint (discussion started on 24 May 2022)

Interactive discussion

Status: closed

RC1:
'Comment on tc-2022-98', Anonymous Referee #1, 04 Jul 2022

The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2022-98/tc-2022-98-RC1-supplement.pdf

Citation: https://doi.org/10.5194/tc-2022-98-RC1
- AC1: 'Reply on RC1', Felix L. Müller, 20 Oct 2022
  
  Dear Reviewer 1,
  thank you very much for your review. We think it contributes greatly to improve the manuscript. Our responses to your review can be found in the attached file.
  Thank you very much.
  All the best
  
  Felix Müller on behalf of my co-authors
  
  Citation: https://doi.org/10.5194/tc-2022-98-AC1
- AC4: 'Reply on RC1', Felix L. Müller, 20 Oct 2022
  
  Dear Reviewer 1,
  please find also a track-change version of the manuscript.
  Thank you.
  
  Citation: https://doi.org/10.5194/tc-2022-98-AC4
RC2:
'Comment on tc-2022-98', Anonymous Referee #2, 13 Sep 2022

The comment was uploaded in the form of a supplement: https://tc.copernicus.org/preprints/tc-2022-98/tc-2022-98-RC2-supplement.pdf

Citation: https://doi.org/10.5194/tc-2022-98-RC2
- AC2: 'Reply on RC2', Felix L. Müller, 20 Oct 2022
  
  Dear Reviewer 2,
  
  thank you very much for your review. We think it contributes greatly to improve the manuscript. Our responses to your review can be found in the attached file.
  
  Thank you very much.
  
  All the best
  
  Felix Müller on behalf of my co-authors
  
  Citation: https://doi.org/10.5194/tc-2022-98-AC2
- AC3: 'Reply on RC2', Felix L. Müller, 20 Oct 2022
  
  Dear Reviewer 2,
  please find also a track-change version of the manuscript.
  Thank you.
  
  Citation: https://doi.org/10.5194/tc-2022-98-AC3

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Publish subject to revisions (further review by editor and referees) (31 Oct 2022) by David Schroeder

AR by Felix L. Müller on behalf of the Authors (07 Nov 2022) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (07 Nov 2022) by David Schroeder

RR by Anonymous Referee #1 (21 Nov 2022)

RR by Anonymous Referee #2 (15 Dec 2022)

Suggestions for revision or reasons for rejection

The authors have made substantial improvements to the paper by thoroughly addressing several of the reviewer comments. In cases where the authors did not act on a reviewer comment, they provided a justification for their decision. The authors should be commended for their attention to detail in making the revised version of the manuscript a worthwhile contribution to The Cryosphere pending some additional minor comments and corrections.
By line number.
L7: thin-ice thickness (singular not plural since it is a variable)
L9: change “or to directly adjust” to “or direct adjustments to”
L9: “… specifically to” should be “…. for”
L11: delete “mere”
L12: delete “basic”
L13” delete “between”
L20: delete “sea-ice” before leads and polynyas
L27: delete “the”
L38: change “allows …. measure” to “enables direct measurements of”
L52: This doesn’t need to be a new paragraph.
L57: Since this is mentioning the current situation, it would be appropriate to update this to the combined SMAP-SMOS thickness product.
L64: delete “the capabilities of”
L79: should be “highlights”
L83-84: It would be better to be consistent with ESA stated primary Cryosat-2 objectives of measuring diminishing land and sea ice in polar regions, for understanding the role of climate in diminshing polar ice.
L85: delete “the cryosphere”
L97: change waveform returns to “waveforms”
L102: Clarify the wavelengths associated with these band numbers.
L111: Since Sentinel 1B is no longer operative, it would be appropriate to update this sentence to better reflect the situation. Or change it to past tense to reflect the situation relevant to the study.
L115: provides
L116: delete “in the ice covered ocean”
L121: “a” shows up twice
L128: map projection (no “s”)
L129: It is unclear what is meant by theoretical size. If this is an estimate it should be indicated as such.
L142: Please clarify what is meant by observations here. It is relatively straightforward but someone outside of altimetry might find it difficult to follow whether an observation is a track or a waveform (or other).
L157: Delete "see". Also "Fig." or "Figure" be consistent.
L191: It would be more appropriate to define this when first used as TIT and use TIT throughout.
L202: Confusing sentence. Do you mean “… NCEP2 reanalysis by Kalnay et al. … “?
L204: TIT
L209: Since comparisons are also made to SMOS, it would be better to mention that here too. Currently it is on L217.
L225: Where it is mention that reasons are two-fold, some consideration of the geometric i.e. positional accuracy of the different sensing systems should also be considered here. At least nominally, how well is everything co-located?
L228: add a space after small
L243: Unclear what is meant by “fall up”. Contain?
L255: “… change in roughness …”
L257: Change “But is” to “It”
L262: Delete “really”
L275: change “but also” to “and”
L279: It would be helpful to have some context on expected growth rates of sea ice, or at least how long it takes for a lead to freeze over, with reason given that it will be dependent on e.g. air temp, water temp, etc. (minutes, hours, days, etc.)?
Figure 8 caption: the average feature values are blue circles not “blue dotted line”
L382: Is it noise, or just a more variable signal (less peakiness)?
L391: For the reason stated in the sentence beginning “Moreover …” the summary is better and stronger without this in it.

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ED: Publish subject to minor revisions (review by editor) (16 Dec 2022) by David Schroeder

AR by Felix L. Müller on behalf of the Authors (16 Jan 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (22 Jan 2023) by David Schroeder

AR by Felix L. Müller on behalf of the Authors (30 Jan 2023)

Short summary

Thinning sea ice has significant impacts on the energy exchange between the atmosphere and the ocean. In this study we present visual and quantitative comparisons of thin-ice detections obtained from classified Cryosat-2 radar reflections and thin-ice-thickness estimates derived from MODIS thermal-infrared imagery. In addition to good comparability, the results of the study indicate the potential for a deeper understanding of sea ice in the polar seas and improved processing of altimeter data.