the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Assessing the Material Coherence of Mesoscale Eddies as described from In Situ Data
Abstract. Mesoscale eddies are a ubiquitous feature of the global ocean. According to Lagrangian theory, these eddies often transport a distinct water mass within their cores, making them materially coherent. This study aims to determine if such a distinct water mass exists in eddy cores, thereby verifying their material coherence using in situ data, despite the lack of temporal continuity. We introduce the term "thermohaline coherence" to describe this approach. Identifying such a water mass would signal Lagrangian transport from the eddy formation region. We analyzed the water masses at the cores of various eddies sampled during eight research cruises, using high-resolution data (approximately 20 km horizontally and 10 m vertically). We revisited coherence definitions and checked data accuracy. Comparing the horizontal positions of these core anomalies with eddy surface signatures revealed that surface data alone are insufficient for characterizing the eddy material coherence. To calculate eddy volumes, we compare thermohaline anomalies with other criteria and we present two methods for extrapolating eddy volumes from a single hydrographic section. The results show that the outermost closed contour of the Brunt-Väisälä frequency anomaly at each depth provides a reliable approximation for the eddy boundary.
Status: closed
-
RC1: 'Comment on egusphere-2024-2029', Anonymous Referee #1, 10 Jul 2024
The authors of this manuscript should conduct a more comprehensive review of the extant literature on material frame-indifferent (i.e., objective) coherent vortex detection. The manuscript contains several inaccurate or unsubstantiated statements, including the following:
1) 'Flierl (1981) showed that when the tangential velocity of the vortex is higher than its translational velocity, fluid particles are trapped in the vortex core.' This claim is more an expression of belief rather than a rigorous conclusion, as velocity is dependent on the observer.
2) 'In particular, MC theory ignores the fact that water masses at the edge of eddies can change their properties due to various types of instabilities.' This statement is incorrect because, if a vortex is characterized as materially coherent, no fluid can traverse its boundary. More precisely, no material surface can be intersected by fluid flow since it is flow-invariant, regardless of its coherence.
3) 'Furthermore, MC theory is based only on fluid flow and does not consider the potential permeability of the eddy boundary due to diffusion processes or lateral intrusion (Joyce, 1977, 1984; Ruddick et al., 2010).' This is inaccurate since the boundaries of geodesically-detected coherent material vortices serve as minimizers of diffusion (refer to the Annual Review of Fluid Mechanics paper by Haller).
4) 'We revisited coherence definitions and checked data accuracy.' This manuscript does not encompass an examination of coherent material vortex framing. Indeed, the manuscript lacks any explicit articulation or statement concerning this subject matter.
5) 'Comparing the horizontal positions of these core anomalies with eddy surface signatures revealed that surface data alone are insufficient for characterizing the eddy material coherence.' This is plausible, but to assess it, time-dependent flow data must be analyzed using an objective method.
Beyond these imprecise statements, the TC criterion remains nebulous and can only be regarded as qualitative in nature; temporal flow data are imperative to establish coherence. All criteria (gradients; potential vorticity — an observer-dependent quantity; pythagorean arguments) are applied to instantaneous snapshots of observed mass fields. A temporal history is requisite to ascertain if the 'gradient of a property of some kind' is conserved under advection by the flow. It is evident that transect data are unsuitable for this type of analysis.
In conclusion, I am unable to endorse the publication of this manuscript. I acknowledge the significant effort expended by the author in analyzing in-situ oceanographic campaign data, which holds intrinsic value. However, I urge the author to consider presenting their analysis within an alternative context, as the current application towards assessing material coherence is not appropriate for the available data.
Citation: https://doi.org/10.5194/egusphere-2024-2029-RC1 - AC1: 'Reply on RC1', Yan Barabinot, 16 Jul 2024
-
RC2: 'Comment on egusphere-2024-2029', Anonymous Referee #2, 12 Aug 2024
-
AC2: 'Reply on RC2', Yan Barabinot, 23 Aug 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2029/egusphere-2024-2029-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Yan Barabinot, 23 Aug 2024
-
RC3: 'Comment on egusphere-2024-2029', Anonymous Referee #3, 11 Sep 2024
This manuscript details the analysis of in situ float data along with CTD sections to asses how eddies transport material. This work represents a valuable contribution to the study of eddy dynamics and can be strengthened by the addition of specific derivations to go along w the text. My suggestion is that the authors consider my comments and maybe add some proofs that the methods of defining material coherence are similar or different. If this is addressed it is my opinion that this paper be published.
My recommendation is to back up the arguments made in to the introduction. The authors compare multiple methods to estimate eddy transport and do so only describing similarities and differences. This section needs to be analytical and needs to show mathematically what is described in the text. At the present it is not sufficient to just say two methods are the same or different with out showing it.
As to the analysis and results, I find them truly interesting and am excited to have them become part of the literature. The strengthening of the introduction in my opinion would make this a very valuable paper.
Citation: https://doi.org/10.5194/egusphere-2024-2029-RC3 -
AC3: 'Reply on RC3', Yan Barabinot, 12 Sep 2024
We thank the reviewer for his/her positive comment and his/her suggestion. However, we are not sure to understand what is stipulated in the comment especially regarding the addition of mathematical proofs. We are not sure whether this relates to the confrontation between Eulerian and Lagrangian visions or to the comparison of criteria applied to a vertical section. The mathematical confrontation between Eulerian and Lagrangian vision was treated in great details by the papers of Haller et al. cited in the introduction. Moreover, several Eulerian and Lagrangian criteria are used to detect the material coherent core of eddies making the mathematical development long to perform. In addition, criteria are tested through their ability to keep particles in the eddy cores and are better assessed using numerical simulations. However, we remain open to include an analytical idealized case in the introduction of the revised version that highlights the difference between an Eulerian and a Lagrangian criterion. Regarding the comparison of Eulerian criteria applied to vertical ship sections, Barabinot et al. (2024) proposes a comparison of these criteria which we supplement in part 3 of our manuscript.
Citation: https://doi.org/10.5194/egusphere-2024-2029-AC3
-
AC3: 'Reply on RC3', Yan Barabinot, 12 Sep 2024
-
EC1: 'Comment on egusphere-2024-2029', Karen J. Heywood, 11 Sep 2024
I am grateful to all three reviewers for their helpful comments and suggestions on this paper. The three reports raise a range of different concerns, and make many suggestions to strengthen the paper. Thank you to the authors for their responses to the first two reviewers; I invite you to respond to reviewer 3 also. Once the open discussion phase closes tomorrow, you will be invited to post a final response, and then to upload a revised manuscript together with the detailed responses to the reviewers (these may be, but do not have to be, the same responses that you posted in the open discussion). You will have a month or so to do this. I look forward to considering your revised paper.
Citation: https://doi.org/10.5194/egusphere-2024-2029-EC1 -
AC4: 'Reply on EC1', Yan Barabinot, 12 Sep 2024
We would like to thank again the three referees for their precious comments on our article and the editor for the good coordination of revisions. In the revised version of the manuscript, we will make sure to account for every comment made by referees in order to propose a clearer version of our work.
Citation: https://doi.org/10.5194/egusphere-2024-2029-AC4
-
AC4: 'Reply on EC1', Yan Barabinot, 12 Sep 2024
Status: closed
-
RC1: 'Comment on egusphere-2024-2029', Anonymous Referee #1, 10 Jul 2024
The authors of this manuscript should conduct a more comprehensive review of the extant literature on material frame-indifferent (i.e., objective) coherent vortex detection. The manuscript contains several inaccurate or unsubstantiated statements, including the following:
1) 'Flierl (1981) showed that when the tangential velocity of the vortex is higher than its translational velocity, fluid particles are trapped in the vortex core.' This claim is more an expression of belief rather than a rigorous conclusion, as velocity is dependent on the observer.
2) 'In particular, MC theory ignores the fact that water masses at the edge of eddies can change their properties due to various types of instabilities.' This statement is incorrect because, if a vortex is characterized as materially coherent, no fluid can traverse its boundary. More precisely, no material surface can be intersected by fluid flow since it is flow-invariant, regardless of its coherence.
3) 'Furthermore, MC theory is based only on fluid flow and does not consider the potential permeability of the eddy boundary due to diffusion processes or lateral intrusion (Joyce, 1977, 1984; Ruddick et al., 2010).' This is inaccurate since the boundaries of geodesically-detected coherent material vortices serve as minimizers of diffusion (refer to the Annual Review of Fluid Mechanics paper by Haller).
4) 'We revisited coherence definitions and checked data accuracy.' This manuscript does not encompass an examination of coherent material vortex framing. Indeed, the manuscript lacks any explicit articulation or statement concerning this subject matter.
5) 'Comparing the horizontal positions of these core anomalies with eddy surface signatures revealed that surface data alone are insufficient for characterizing the eddy material coherence.' This is plausible, but to assess it, time-dependent flow data must be analyzed using an objective method.
Beyond these imprecise statements, the TC criterion remains nebulous and can only be regarded as qualitative in nature; temporal flow data are imperative to establish coherence. All criteria (gradients; potential vorticity — an observer-dependent quantity; pythagorean arguments) are applied to instantaneous snapshots of observed mass fields. A temporal history is requisite to ascertain if the 'gradient of a property of some kind' is conserved under advection by the flow. It is evident that transect data are unsuitable for this type of analysis.
In conclusion, I am unable to endorse the publication of this manuscript. I acknowledge the significant effort expended by the author in analyzing in-situ oceanographic campaign data, which holds intrinsic value. However, I urge the author to consider presenting their analysis within an alternative context, as the current application towards assessing material coherence is not appropriate for the available data.
Citation: https://doi.org/10.5194/egusphere-2024-2029-RC1 - AC1: 'Reply on RC1', Yan Barabinot, 16 Jul 2024
-
RC2: 'Comment on egusphere-2024-2029', Anonymous Referee #2, 12 Aug 2024
-
AC2: 'Reply on RC2', Yan Barabinot, 23 Aug 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2029/egusphere-2024-2029-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Yan Barabinot, 23 Aug 2024
-
RC3: 'Comment on egusphere-2024-2029', Anonymous Referee #3, 11 Sep 2024
This manuscript details the analysis of in situ float data along with CTD sections to asses how eddies transport material. This work represents a valuable contribution to the study of eddy dynamics and can be strengthened by the addition of specific derivations to go along w the text. My suggestion is that the authors consider my comments and maybe add some proofs that the methods of defining material coherence are similar or different. If this is addressed it is my opinion that this paper be published.
My recommendation is to back up the arguments made in to the introduction. The authors compare multiple methods to estimate eddy transport and do so only describing similarities and differences. This section needs to be analytical and needs to show mathematically what is described in the text. At the present it is not sufficient to just say two methods are the same or different with out showing it.
As to the analysis and results, I find them truly interesting and am excited to have them become part of the literature. The strengthening of the introduction in my opinion would make this a very valuable paper.
Citation: https://doi.org/10.5194/egusphere-2024-2029-RC3 -
AC3: 'Reply on RC3', Yan Barabinot, 12 Sep 2024
We thank the reviewer for his/her positive comment and his/her suggestion. However, we are not sure to understand what is stipulated in the comment especially regarding the addition of mathematical proofs. We are not sure whether this relates to the confrontation between Eulerian and Lagrangian visions or to the comparison of criteria applied to a vertical section. The mathematical confrontation between Eulerian and Lagrangian vision was treated in great details by the papers of Haller et al. cited in the introduction. Moreover, several Eulerian and Lagrangian criteria are used to detect the material coherent core of eddies making the mathematical development long to perform. In addition, criteria are tested through their ability to keep particles in the eddy cores and are better assessed using numerical simulations. However, we remain open to include an analytical idealized case in the introduction of the revised version that highlights the difference between an Eulerian and a Lagrangian criterion. Regarding the comparison of Eulerian criteria applied to vertical ship sections, Barabinot et al. (2024) proposes a comparison of these criteria which we supplement in part 3 of our manuscript.
Citation: https://doi.org/10.5194/egusphere-2024-2029-AC3
-
AC3: 'Reply on RC3', Yan Barabinot, 12 Sep 2024
-
EC1: 'Comment on egusphere-2024-2029', Karen J. Heywood, 11 Sep 2024
I am grateful to all three reviewers for their helpful comments and suggestions on this paper. The three reports raise a range of different concerns, and make many suggestions to strengthen the paper. Thank you to the authors for their responses to the first two reviewers; I invite you to respond to reviewer 3 also. Once the open discussion phase closes tomorrow, you will be invited to post a final response, and then to upload a revised manuscript together with the detailed responses to the reviewers (these may be, but do not have to be, the same responses that you posted in the open discussion). You will have a month or so to do this. I look forward to considering your revised paper.
Citation: https://doi.org/10.5194/egusphere-2024-2029-EC1 -
AC4: 'Reply on EC1', Yan Barabinot, 12 Sep 2024
We would like to thank again the three referees for their precious comments on our article and the editor for the good coordination of revisions. In the revised version of the manuscript, we will make sure to account for every comment made by referees in order to propose a clearer version of our work.
Citation: https://doi.org/10.5194/egusphere-2024-2029-AC4
-
AC4: 'Reply on EC1', Yan Barabinot, 12 Sep 2024
Viewed
Since the preprint corresponding to this journal article was posted outside of Copernicus Publications, the preprint-related metrics are limited to HTML views.
HTML | XML | Total | BibTeX | EndNote | |
---|---|---|---|---|---|
194 | 0 | 0 | 194 | 0 | 0 |
- HTML: 194
- PDF: 0
- XML: 0
- Total: 194
- BibTeX: 0
- EndNote: 0
Viewed (geographical distribution)
Since the preprint corresponding to this journal article was posted outside of Copernicus Publications, the preprint-related metrics are limited to HTML views.
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1