Journal cover Journal topic
Nonlinear Processes in Geophysics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

IF value: 1.558
IF1.558
IF 5-year value: 1.475
IF 5-year
1.475
CiteScore value: 2.8
CiteScore
2.8
SNIP value: 0.921
SNIP0.921
IPP value: 1.56
IPP1.56
SJR value: 0.571
SJR0.571
Scimago H <br class='widget-line-break'>index value: 55
Scimago H
index
55
h5-index value: 22
h5-index22
Preprints
https://doi.org/10.5194/npg-2020-36
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/npg-2020-36
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  31 Aug 2020

31 Aug 2020

Review status
This preprint is currently under review for the journal NPG.

Extracting statistically significant eddy signals from large Lagrangian datasets using wavelet ridge analysis, with application to the Gulf of Mexico

Jonathan M. Lilly1 and Paula Perez-Brunius2 Jonathan M. Lilly and Paula Perez-Brunius
  • 1Theiss Research, La Jolla, California, USA
  • 2Departamento de Oceanografía, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Mexico

Abstract. A method for objectively extracting the displacement signals associated with coherent eddies from Lagrangian trajectories is presented, refined, and applied to a large dataset of 3761 surface drifters from the Gulf of Mexico. The method, wavelet ridge analysis, is modified to exclude the possibility of features changing from rotating in the cyclonic sense to rotating in the anticyclonic sense or vice-versa, transitions that would be physically unrealistic for a coherent eddy. A means for formally assessing statistical significance is introduced, addressing the issue of "false positives" arising by chance from an unstructured turbulent background, and opening the door to confident application of the method to very large datasets. Significance is measured in a two-dimensional parameter space by comparison with a stochastic dataset having statistical and spectral properties that match the original, but lacking organized oscillations due to eddies or waves. The application to the Gulf of Mexico reveals massive asymmetries between cyclones and anticyclones, with anticyclones dominating at radii larger than about 50 km, but an unexpectedly rich population of highly nonlinear cyclones dominating at smaller radii. Both the method and the Gulf of Mexico eddy dataset are made freely available to the community for use in future research.

Jonathan M. Lilly and Paula Perez-Brunius

Interactive discussion

Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Login for Authors/Editors] [Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Jonathan M. Lilly and Paula Perez-Brunius

Data sets

GulfDrifters: A consolidated surface drifter dataset for the Gulf of Mexico Jonathan M. Lilly and Paula Pérez-Brunius https://doi.org/10.5281/zenodo.3978793

The Gulf of Mexico Eddy Dataset (GOMED), a census of statistically significant eddy-like events from all available surface drifter data Jonathan M. Lilly and Paula Pérez-Brunius https://doi.org/10.5281/zenodo.3978803

Jonathan M. Lilly and Paula Perez-Brunius

Viewed

Total article views: 613 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
542 64 7 613 5 6
  • HTML: 542
  • PDF: 64
  • XML: 7
  • Total: 613
  • BibTeX: 5
  • EndNote: 6
Views and downloads (calculated since 31 Aug 2020)
Cumulative views and downloads (calculated since 31 Aug 2020)

Viewed (geographical distribution)

Total article views: 444 (including HTML, PDF, and XML) Thereof 442 with geography defined and 2 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Saved

No saved metrics found.

Discussed

No discussed metrics found.
Latest update: 24 Nov 2020
Publications Copernicus
Download
Short summary
Long-lived eddies are an important part of the ocean circulation. Here a dataset for studying eddies in the Gulf of Mexico is created through the analysis of trajectories of drifting instruments. The method involves the identification of quasi-periodic signals, characteristic of particles trapped in eddies, from the displacement records, followed by the creation of a measure of statistical significance. It is expected that this dataset will be of use to other authors studying this region.
Long-lived eddies are an important part of the ocean circulation. Here a dataset for studying...
Citation