Vertical structure of ocean surface currents under high winds from massive arrays of drifters

Lodise, John; Özgökmen, Tamay; Griffa, Annalisa; Berta, Maristella

doi:https://doi.org/10.5194/os-15-1627-2019

Articles | Volume 15, issue 6

https://doi.org/10.5194/os-15-1627-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-15-1627-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 6

Research article

|

09 Dec 2019

Research article |

| 09 Dec 2019

Vertical structure of ocean surface currents under high winds from massive arrays of drifters

John Lodise, Tamay Özgökmen, Annalisa Griffa, and Maristella Berta

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Final revised paper (published on 09 Dec 2019)
Preprint (discussion started on 05 Mar 2019)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review', Anonymous Referee #1, 30 Apr 2019
- AC1: 'Response to Referee #1 on "Vertical Structure of Ocean Surface Currents Under High Winds from Massive Arrays of Drifters"', John Lodise, 31 May 2019
- AC4: 'Response to Referee #1', John Lodise, 31 May 2019
RC2: 'Review of Lodise et al', Anonymous Referee #2, 02 May 2019
- AC2: 'Response to Referee #2', John Lodise, 31 May 2019
- AC5: 'Response to Referee #2', John Lodise, 31 May 2019
RC3: 'Review of "Vertical Structure of Ocean Surface Currents Under High Winds from Massive Arrays of Drifters"', Fabrice Ardhuin, 03 May 2019
- AC3: 'Response to Referee #3', John Lodise, 31 May 2019
- AC6: 'Response to Referee #3', John Lodise, 31 May 2019
EC1: 'delayed comments from Fabrice Ardhuin', Ilker Fer, 20 Jul 2019

Peer-review completion

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

AR by John Lodise on behalf of the Authors (31 May 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Jun 2019) by Ilker Fer

RR by Anonymous Referee #1 (24 Jun 2019)

RR by Anonymous Referee #2 (26 Jun 2019)

Suggestions for revision or reasons for rejection

My main concern about the use of LAVA to derive the so-called "pre-existing circulation" has in my opinion not been addressed properly. By all means, LAVA might be a good method to estimate the Eulerian circulation for practical purposes such as oil spill drift modelling, where some uncertainty with regards to the wind and wave induced drift components can be accepted. In this paper, however, where proper identification of the Eulerian background circulation is paramount, I'm still not convinced that it is suitable.

The comparison with SST is inadequate. In some places the LAVA estimates of the currents go across the fronts, in other places along the fronts, and the interpretation will necessarily be subjective. Crude estimates of the circulation from SST can be obtained using maximum cross correlation methods, but even better would be to estimate surface geostrophic velocities from SSH and compare that with the LAVA results (or use the SSH estimates instead). I also wonder why the authors haven't investigated other sources of independent ocean model data that might be more suitable. Numerical models are dismissed out of hand with a couple of references that date back to 2008 and 2011, and I would expect a lot has happened since that time.

I cannot recommend publication unless a proper comparison of LAVA estimates with other estimates are shown, or alternative estimates are used instead for the background circulation, and until that time I'm reluctant to comment on other minor issues in the paper. There is one exception, though: The new Fig. 4 shows that the wave model component consistently underestimates the wave periods. This is has a bearing on the accuracy of the Stokes drift estimates. A more in depth comparison of the high frequency part of the wave spectrum, also commenting on the ability of the wave buoy to capture high frequency waves, should be presented.

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ED: Reconsider after major revisions (18 Jul 2019) by Ilker Fer

AR by John Lodise on behalf of the Authors (29 Aug 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (31 Aug 2019) by Ilker Fer

RR by Anonymous Referee #2 (18 Sep 2019)

RR by Anonymous Referee #1 (25 Sep 2019)

RR by Fabrice Ardhuin (11 Oct 2019)

ED: Publish subject to minor revisions (review by editor) (14 Oct 2019) by Ilker Fer

AR by John Lodise on behalf of the Authors (21 Oct 2019) Author's response Manuscript

ED: Publish as is (22 Oct 2019) by Ilker Fer

Short summary

Observations of ocean currents within the first meter of the surface are made using a large number of ocean drifters of two different draft depths (0–5 and 0–60 cm). We deconstruct the total drifter velocities using an estimate of the regional circulation and a modeled Stokes drift velocity to calculate the purely wind-driven component of each drifter type. We reveal that the wind-driven velocities rotate to the right of the wind, while also decreasing, with depth.