Growth of a young pingo in the Canadian Arctic observed by RADARSAT-2 interferometric satellite radar

Samsonov, Sergey V.; Lantz, Trevor C.; Kokelj, Steven V.; Zhang, Yu

doi:https://doi.org/10.5194/tc-10-799-2016

Articles | Volume 10, issue 2

https://doi.org/10.5194/tc-10-799-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/tc-10-799-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 10, issue 2

Research article

|

15 Apr 2016

Research article |

| 15 Apr 2016

Growth of a young pingo in the Canadian Arctic observed by RADARSAT-2 interferometric satellite radar

Sergey V. Samsonov, Trevor C. Lantz, Steven V. Kokelj, and Yu Zhang

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Final revised paper (published on 15 Apr 2016)
Supplement to the final revised paper
Preprint (discussion started on 20 Nov 2015)

Interactive discussion

Status: closed

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

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- Supplement

RC C2415: 'Comments from referee1', Anonymous Referee #1, 01 Dec 2015
- AC C3019: 'Reply letter (20161013)', Sergey Samsonov, 13 Feb 2016
RC C2483: 'Review of “Growth of a young pingo in the Canadian Arctic observed by RADARSAT-2 interferometric satellite radar” by Samsonov et al.', Anonymous Referee #2, 12 Dec 2015
- AC C3020: 'Reply letter (20161013)', Sergey Samsonov, 13 Feb 2016

Peer-review completion

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

AR by Sergey Samsonov on behalf of the Authors (17 Feb 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 Feb 2016) by Tingjun Zhang (deceased)

RR by Anonymous Referee #3 (18 Feb 2016)

Suggestions for revision or reasons for rejection

Comments on “Growth of a young pingo in the Canadian Arctic
observed by RADARSAT-2 interferometric satellite radar”

The authors observe and analyze the growth of previously unknown and relatively large pingo in Northwestern Canada. While the observational dataset includes historic aerial photos and some field measurements, the bulk of the observations are focused on high-resolution InSAR data collected with RADARSAT-2 over about 3 years from ascending and descending orbits. Using all available, high-coherence InSAR data, the authors infer the deformation time-series over the pingo of interest. The authors use elastic plate and permafrost aggradation models to support their claim that the observed deformation signal is a pingo.

I am not an expert in permafrost morphology or the MSBAS methodology used in this study, but my overall impression of the paper is very positive. The authors applied cutting-edge observational methods and simple physical models to perform a reasonably detailed phenomenological study that at least advances InSAR time-series methodology, if not also our understanding of permafrost morphology. This is my first review of this manuscript, which has already undergone one round of review and revision, and I have no major concerns about its form or substance. I think it will make a fine addition to the literature and recommend it for publication in TC. I only have a few minor comments.

Minor comments (numbers given as page.line):

1.15: The phrase “permafrost aggradation is resulting in the freezing a sub-pingo water lens” is awkward and grammatically incorrect.

1.18: In the phrase “can successfully contribute,” the word “successfully” is redundant.

1.20-1.24: I think the authors are being overly critical of their work and unnecessarily give the reader the impression that the modeling results are a poor fit to the observations (at least that was my impression on first reading). Given the apparent simplicity of the models, the modeled results and the InSAR observations match quite well. While there are discrepancies in the modeled and observed rates, I advise to authors to rephrase this part of the abstract and to cast this mismatch in a more positive light as an opportunity to further develop (not “define limitations of”) the observational methodology and to develop more sophisticated pingo models. The authors do a decent job in the text of noting that the lack of observed deformation in the surrounding pingos is due to limitations in satellite resolution, not in processing methodology, as is suggested in this part of the abstract (at least as I read it initially). Furthermore, if this misfit between modeled and observed rates is important enough to be mentioned in the abstract, then it merits a bit more discussion in the text.

3.71: It appears as though there is a missed reference, as indicted by the question mark in “…pingos by Mackay (1977); ? has shown…”

Sections 2.1 and 2.3: Ensure that any available references and/or websites for these data and software are cited.

Section 2.2: This is just nit-picky, but since one of the main points of this paper is to look at the InSAR results, the authors might consider making this section 2.1.

4.111: “The 3x3 spatial…” is not a complete sentence.

4.112: Do the authors mean geocoded or radar geometry?

5.128: Since data from ascending and descending orbits are being used, shouldn’t matrix A (hat) also contain line-of-sight vectors in addition to the time intervals?

5.130: Again, please be clear about whether these data are in radar or geocoded coordinates.

5.146: Fig 2 and Fig 3 are out of order. Fig 3 is referenced in the text before Fig 2.

7.192: E is Young’s modulus (not module).

7.195: I don’t think Fig. 3 shows the schematic of an elastic pingo model.

7.199: Check the units on Δq/D. If Δq has units of Pa/year and D has units of Pa m3, how do the authors end up with units of Δq/D being m-2?

Fig 3: This plot could be clarified by adding markers to indicate the SAR acquisitions.

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RR by Anonymous Referee #2 (26 Feb 2016)

ED: Publish subject to minor revisions (Editor review) (26 Feb 2016) by Tingjun Zhang (deceased)

AR by Sergey Samsonov on behalf of the Authors (07 Mar 2016) Author's response Manuscript

ED: Publish subject to minor revisions (Editor review) (09 Mar 2016) by Tingjun Zhang (deceased)

AR by Sergey Samsonov on behalf of the Authors (11 Mar 2016) Author's response Manuscript

ED: Publish as is (18 Mar 2016) by Tingjun Zhang (deceased)

AR by Sergey Samsonov on behalf of the Authors (21 Mar 2016)

Short summary

We describe the growth of a very large diameter pingo in the Tuktoyaktuk Coastlands. Analysis of historical data showed that ground uplift initiated sometime between 1935 and 1951 following lake drainage and is largely caused by the growth of intrusive ice. This study demonstrates that satellite radar can successfully contribute to understanding the dynamics of terrain uplift in response to permafrost aggradation and ground ice development in remote polar environments.