Empirical parametrization of Envisat freeboard retrieval of Arctic and Antarctic sea ice based on CryoSat-2: progress in the ESA Climate Change Initiative

Paul, Stephan; Hendricks, Stefan; Ricker, Robert; Kern, Stefan; Rinne, Eero

doi:https://doi.org/10.5194/tc-12-2437-2018

Articles | Volume 12, issue 7

https://doi.org/10.5194/tc-12-2437-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-12-2437-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 12, issue 7

Research article

|

25 Jul 2018

Research article |

| 25 Jul 2018

Empirical parametrization of Envisat freeboard retrieval of Arctic and Antarctic sea ice based on CryoSat-2: progress in the ESA Climate Change Initiative

Stephan Paul, Stefan Hendricks, Robert Ricker, Stefan Kern, and Eero Rinne

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Final revised paper (published on 25 Jul 2018)
Preprint (discussion started on 21 Feb 2018)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of "Consistent CryoSat-2 and Envisat Freeboard Retrieval of Arctic and Antarctic Sea Ice” by Paul et al.', Thomas Armitage, 22 Mar 2018
- AC1: 'Response to RC1', Stephan Paul, 15 May 2018
RC2: 'Review of Paul et al.', Nathan Kurtz, 24 Mar 2018
- AC2: 'Response to RC2', Stephan Paul, 15 May 2018
RC3: '“Consistent CryoSat-2 and Envisat Freeboard Retrieval of Arctic and Antarctic Sea Ice” by Stephan Paul et al.', Sara FLEURY, 28 Mar 2018
- AC3: 'Response to RC3', Stephan Paul, 15 May 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Stephan Paul on behalf of the Authors (15 May 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (21 May 2018) by Jennifer Hutchings

RR by Thomas Armitage (07 Jun 2018)

Suggestions for revision or reasons for rejection

Thanks to the authors for their attempts to address my concerns. With the exception of one minor point (below), I am more or less satisfied with the responses you have provided, and I think the manuscript is in fairly good shape for publication.

Both Nathan Kurtz and myself picked up on the point of retracker thresholds and the discrepancy between the retracking applied to the two different instruments. I am not going to repeat the points here, but in short, you decided to push back against our recommendations on using a consistent approach between the two instruments, as well as both of our recommendations to perform an independent evaluation using e.g., airborne data.

I understand that your reasoning is simply that further development of the CS2 freeboard wasn't part of this study, and you are taking the CS2 data as it is 'off the shelf'. You also explain that you have plans to perform an evaluation, as well as to preform the 'adaptive threshold' procedure to the CS2 data in future. This is fine, as I think I now understand better that the scope of this study was simply to develop the freeboard cross-calibration and nothing else, however, I would like to see this set out clearly and unambiguously in the manuscript. You have set out your purpose at the end of the introduction, but you could add a section in the discussion, or a paragraph in the summary/outlook, simply describing what you have said in response to our comments i.e., you acknowledge there is an inconsistency in using different retracking etc., but that a) the purpose of this paper is simply just the freeboard cross-calibration algorithm, b) you plan on developing a consistent adaptive retracking procedure for CS2 in the future, and c) that the evaluation you have shown isn't independent and you plan on performing a truly independent evaluation further on in the SICCI-2.

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RR by Sara Fleury (28 Jun 2018)

ED: Publish subject to minor revisions (review by editor) (04 Jul 2018) by Jennifer Hutchings

I am very pleased to tell you that this paper can be accepted. There are however some small minor revisions to consider. I would also urge you to consider the one point that Tom Armitage raised again. Please could you consider clarifying the text as regards your choice of thresholds in the retracker. I am in agreement that you should be straight forward on the constraints in the methodology.

This is a solid contribution, and I am looking forward to the long term outcomes and improved ice thickness products.

Please proof read for grammar and consistency.

Minor comments
page 3 line 19: "used input data" seams less jarring as "input data used". And similarly throughout the manuscript.

page 4 line 24 "More information is given in Kern (unpublished manuscript, 2016)." Is this manuscript published yet? Check that it is not a technical manual.

Section 2.2 heading. Should this be moved up to above "As a first step, general filtering is applied"? These lines 1 through 8 seam out of place.
Where ever these sentences should reside in the manuscript they do need some clarification as to what they are referring to.

Make sure all acryonyms are defined. For example is L1b (line 20, page 6) defined earlier. The general readership of The Cryosphere may not understand how satellite products are labled.

page 10 line 27-28: " our Envisat sea-ice-freeboard
estimates featured an overall smaller variation and range than CryoSat-2 estimates" replace than with "compared to".

page 15 line 5: "This is potentially related ice-snow interface" missing "to" at "This is potentially related to ice-snow interface"

page 16, line 20: remove hypen from "lead-". Also in other places.

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AR by Stephan Paul on behalf of the Authors (06 Jul 2018) Author's response Manuscript

ED: Publish as is (11 Jul 2018) by Jennifer Hutchings

Short summary

During ESA's second phase of the Sea Ice Climate Change Initiative (SICCI-2), we developed a novel approach to creating a consistent freeboard data set from Envisat and CryoSat-2. We used consistent procedures that are directly related to the sensors' waveform-echo parameters, instead of applying corrections as a post-processing step. This data set is to our knowledge the first of its kind providing consistent freeboard for the Arctic as well as the Antarctic.