Eddies detected in Delayed-Time (DT) for the entire period [1993 - present]. Variables provided include day-by-day, and for one rotation type (Cyclonic/Anticyclonic) :

- Center position (Longitude and latitude of the center of the best fit circle with the contour of maximum circum-average geostrophic speed);

- Amplitude (|SSH(local_extremum) – SSH(outermost_contour)|);

- Speed radius (Radius of the best fit circle with the contour of maximum circum-average geostrophic speed);

- Speed average (Average geostrophic speed of the contour defining the speed radius);

- Speed profile (Profile speed average values from effective contour inwards to smallest inner contour);

- Effective contour (Largest contour of the detected eddy);

- Speed contour (Contour of maximum circum-average geostrophic speed for the detected eddy).

Note that DT versions differ by the input product used. The “two-satellite” maps are built using at most two altimetric missions, with the Topex-Poseidon and Jason satellites on the same long-term ground tracks, and a second satellite mission, mainly on the ERS-Envisat-Saral-Sentinel-3A ground tracks. As the sampling and the represented scales are stable throughout time, this dataset is considered to be homogeneous in time in terms of climate signals and mesoscale content.

The data used are “two-satellite” daily Delayed Time DUACS2021 version, with the variable Gridded Global Absolute Dynamic Topographies (ADT), from the Copernicus Climate Change Service (C3S) http://climate.copernicus.eu/

Several versions exist : Delayed time "Allsat" and a real time version, described on other metadata sheets.

Types of dataset: multimission altimeter products.

Contents: multimission altimetry-derived eddy trajectories

Format : NetCDF-4 Classic with CF standards.

Statistical analysis document (Figures following Chelton et al. 2011): https://www.aviso.altimetry.fr/fileadmin/documents/data/products/value-added/META3.2_twosat_report.pdf

Reading software: examples in Python programming language. Details on Aviso+ Users Newsletter #14, page 4: Tools for the Mesoscale Eddy Trajectory Atlas, https://www.aviso.altimetry.fr/fileadmin/documents/newsstand/Newsletter/aviso_newsletter_14.pdf#page=4

Code delivery: the open source code is available at https://github.com/AntSimi/py-eddy-tracker from version META3.0 onwards. When using the code, please cite "The code used to compute the Mesoscale Eddy Trajectories Atlas from version 3.0 onwards, was developed in collaboration between IMEDEA (E. Mason) and CLS, is freely available under GNU General Public License https://github.com/AntSimi/py-eddy-tracker ".

Image of the month, June 2017: Eddies everywhere, https://www.aviso.altimetry.fr/en/news/image-of-the-month/2017/jun-2017-eddies-everywhere.html

References:

- Pegliasco et al., OSTST 2022: A New Global Mesoscale Eddy Trajectories Atlas Derived from Altimetry : Presentation and Future Evolutions https://ostst.aviso.altimetry.fr/fileadmin/user_upload/OSTST2022/Presentations/SC32022-A_New_Global_Mesoscale_Eddy_Trajectory_Atlas_Derived_from_Altimetry___Presentation_and_Future_Evolutions.pdf

- Pegliasco, C., Delepoulle, A., Mason, E., Morrow, R., Faugère, Y., Dibarboure, G., 2022. META3.1exp: a new global mesoscale eddy trajectory atlas derived from altimetry. Earth Syst. Sci. Data 14, 1087–1107. https://doi.org/10.5194/essd-14-1087-2022

- Mason, E., A. Pascual, and J.C. McWilliams, 2014: A New Sea Surface Height–Based Code for Oceanic Mesoscale Eddy Tracking. J. Atmos. Oceanic Technol., 31, 1181–1188, https://doi.org/10.1175/JTECH-D-14-00019.1