Network-based study of Lagrangian transport and mixing

Padberg-Gehle, Kathrin; Schneide, Christiane

doi:https://doi.org/10.5194/npg-24-661-2017

Articles | Volume 24, issue 4

https://doi.org/10.5194/npg-24-661-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

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Current perspectives in modelling, monitoring, and predicting...

https://doi.org/10.5194/npg-24-661-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 24, issue 4

Research article

|

20 Oct 2017

Research article |

| 20 Oct 2017

Network-based study of Lagrangian transport and mixing

Kathrin Padberg-Gehle and Christiane Schneide

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Final revised paper (published on 20 Oct 2017)
Preprint (discussion started on 17 Feb 2017)

Interactive discussion

Status: closed

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

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RC1: 'Review of the manuscript 10.5194/npg-2017-4, 2017 entitled: “Network-based study of Lagrangian transport and mixing” by Kathrin Padberg-Gehle and Christiane Schneide.', Anonymous Referee #1, 04 Mar 2017
RC2: 'Referee Comment on "Network-based study of Lagrangian transport and mixing" by Kathrin Padberg-Gehle and Christiane Schneide (npg-2017-4)', Gabor Drotos, 24 Mar 2017
AC1: 'Response to referee reports', Kathrin Padberg-Gehle, 13 Jul 2017

Peer-review completion

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

AR by Kathrin Padberg-Gehle on behalf of the Authors (04 Aug 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (11 Aug 2017) by Cristóbal López

RR by Gabor Drotos (24 Aug 2017)

Suggestions for revision or reasons for rejection

In the revised version of the paper entitled "Network-based study of Lagrangian transport and mixing" by Kathrin Padberg-Gehle and Chrisiane Schneide, and in their response to the referee comments, the authors have addressed all criticisms and suggestions. The new, very interesting results, the additional, careful discussion of certain points, and the amendments in the formulation make the paper acceptable for final publication.

Nevertheless, I list a few observations regarding the novelties in the revised version that should be addressed.

- The authors state in their response to Referee #1, in point 5, that they will provide more details about the spectral analysis in section 2. However, I did not find this part in the paper, neither in section 2, nor in section 3.3 (where it would fit better). (This discussion is, however, already part of the response, so it just needs to be adapted to the text of the paper, and included at an appropriate position.)

- Page 7, lines 25-26: From this discussion, a conclusion should be explicitly drawn about the reasonable choice for the investigated range of epsilon.

- Page 8, lines 9-16: It should be mentioned that the jet core is not resolved by any of the local network measures in the considered (sparse) setting.

- In the same paragraph: It should be explained why "blurring the local information" (with increasing epsilon) results in increased average node degree <d>_nn in the regular regions compared to the mixing regions.

- Page 12, lines 10-11: It would be beneficial to extend the sentence "The local clustering coefficient is large in particular in the core of the vortex" by adding: ", where the node degree and the average node degree take on smaller values", or something similar.

- Page 12, lines 15-16: The phrasing "with isolated yellow regions in the background flow" might need to be clarified, e.g. like "with small, isolated yellow regions dispersed in the background flow".

Finally, responding to point 2 of the authors' response to my earlier comment, I agree that more numerical results should not be displayed for the Bickley jet. At the same time, I emphasize again that the dependence on the time interval carries useful information about the inherent properties of the system's dynamics (as illustrated by the case of the stratospheric polar vortex), and should not be "fixed by the user or by the available data". (If only restricted data is available, subintervals can be considered.)

Apart from the above points, I find the paper to be really well-composed, and I recommend acceptance.

Gabor Drotos

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ED: Publish subject to minor revisions (further review by Editor) (04 Sep 2017) by Cristóbal López

AR by Kathrin Padberg-Gehle on behalf of the Authors (08 Sep 2017) Author's response Manuscript

ED: Publish as is (13 Sep 2017) by Cristóbal López

AR by Kathrin Padberg-Gehle on behalf of the Authors (19 Sep 2017)

Short summary

Transport and mixing processes in fluid flows are crucially influenced by coherent structures, such as eddies, gyres, or jets in geophysical flows. We propose a very simple and computationally efficient approach for analyzing coherent behavior in fluid flows. The central object is a flow network constructed directly from particle trajectories. The network's local and spectral properties are shown to give a very good indication of coherent as well as mixing regions in the underlying flow.