Intermittency of Arctic–mid-latitude teleconnections: stratospheric pathway between autumn sea ice and the winter North Atlantic Oscillation

Siew, Peter Yu Feng; Li, Camille; Sobolowski, Stefan Pieter; King, Martin Peter

doi:https://doi.org/10.5194/wcd-1-261-2020

Articles | Volume 1, issue 1

https://doi.org/10.5194/wcd-1-261-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/wcd-1-261-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 1, issue 1

Research article

|

12 May 2020

Research article |

| 12 May 2020

Intermittency of Arctic–mid-latitude teleconnections: stratospheric pathway between autumn sea ice and the winter North Atlantic Oscillation

Peter Yu Feng Siew, Camille Li, Stefan Pieter Sobolowski, and Martin Peter King

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Final revised paper (published on 12 May 2020)
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Preprint (discussion started on 14 Nov 2019)
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Interactive discussion

Status: closed

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

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RC1: 'A thorough investigation of the autumn sea ice impact on the winter climate', Anonymous Referee #1, 10 Dec 2019
RC2: 'Review', Anonymous Referee #2, 12 Dec 2019
AC1: 'Response to referees', Yu Feng Siew, 07 Feb 2020

Peer-review completion

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

AR by Peter Yu Feng Siew on behalf of the Authors (06 Mar 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Mar 2020) by Yang Zhang

RR by Anonymous Referee #1 (18 Mar 2020)

RR by Anonymous Referee #2 (30 Mar 2020)

For final publication, the manuscript should be

accepted as is

accepted subject to technical corrections

accepted subject to minor revisions

reconsidered after major revisions

I would be willing to review the revised paper, if the editor considers it necessary.

I am not willing to review the revised paper.

rejected

Suggestions for revision or reasons for rejection

General Comment

This is my second review of the manuscript “Intermittency of Arctic-midlatitude teleconnections: stratospheric pathway between autumn sea ice and the winter NAO”. The authors did a great job in addressing all of my comments and I much appreciate the overall thorough analysis and well written paper. In my opinion the manuscript is ready for publication. As outlined below, I only have a few minor comments left.

Minor Comments

Determining the number of independent tests m to calculate the adjusted P-value is indeed not trivial. Again, I don´t think it is a major issue here, so I agree with the authors that it can be ignored. But in case the authors are interested, I recommend this paper here: “Estimating and Controlling the False Discovery Rate for the PC Algorithm Using Edge-Specific P-Values”, https://arxiv.org/abs/1607.03975. In this paper, it is suggested to take the maximum p-value for each link over all conditional independence tests, which is yet a very conservative estimate!

L40-41: Maybe worth noting that this is consistent with Kolstad and Screen 2019. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL083059

Section 2.2. I think the authors should at some point mention that the algorithm used to construct the CEN is called PCMCI (Runge et al. 2019).

L 107: The wording “true causal driver” is a bit misleading.

Section 3.2 Is the Link from Urals_Dec to vT_Dec calculated from the contemporaneous link strength? That is, can it really interpreted here as the casual effect on a given path? As the time-resolution and the relevant lags remain as an issue, maybe it should be made a bit clearer that this section describes only an attempt to estimate the total causal effect of the stratospheric pathway.

L264: why is the physical interpretation unclear? I think it makes even sense that VT is not “needed” as a mediator if the pathway only takes a month and not two.

L279: The same is probably true for extremely strong SPV states.

L306: I don’t understand this sentence.

L340 and following: Again, I think it makes sense to differentiate the intermittencies of the upward and of the downward stratospheric coupling and quantify both.

L358: Why “however”?

372: Or SIC contributes to ENSO intermittency? The NAO can probably be seen as a collider of ENSO and SIC effect.

L407 and following: I fully agree with the statement that CEN “depends critically on the careful selection of input variables”. However, the claim that links disappear “if a new variable is added because of changes in the results of the partial correlations tests” seems a bit unfair to me because this effect is fully understood in a statistical sense: If the time-series are too similar, then they cancel out each other when testing for conditional independence. Therefore, choice of relevant data is crucial for CEN, as it is for any data analysis.

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ED: Publish subject to minor revisions (review by editor) (31 Mar 2020) by Yang Zhang

AR by Peter Yu Feng Siew on behalf of the Authors (11 Apr 2020) Author's response Manuscript

ED: Publish as is (22 Apr 2020) by Yang Zhang

AR by Peter Yu Feng Siew on behalf of the Authors (27 Apr 2020)

Short summary

Arctic sea ice loss has been linked to changes in mid-latitude weather and climate. However, the literature offers differing views on the strength, robustness, and even existence of these linkages. We use a statistical tool (Causal Effect Networks) to show that one proposed pathway linking Barents–Kara ice and mid-latitude circulation is intermittent in observations and likely only active under certain conditions. This result may help explain apparent inconsistencies across previous studies.