Recently, associate researcher Liu Tongya of the SIO published the research paper entitled “A global Lagrangian eddy dataset based on satellite altimetry” in Earth System Science Data (IF: 11.815), a top journal in the field of geosciences, and released a set of Lagrangian eddy data products based on satellite observations. As the first author and corresponding author of the paper, associate researcher Liu Tongya, collaborated with Professor Ryan Abernathey of Columbia University to complete the study.

Mesoscale eddies are ubiquitous in the ocean, and they carry about 90% of the kinetic energy of the ocean and play a vital role in the transport of matter and energy in the global ocean. At present, nearly all existing eddy datasets are based on the Eulerian method. However, it has been pointed out that the eddies identified based on the Eulerian method are not real coherent structures. These eddies usually have strong water exchange with the surrounding water body during their life cycle, and estimating eddy-induced transport based on this may greatly overestimate the ability of eddies to carry substances. Compared with the Eulerian method, the steps of detecting eddies by Lagrangian method are relatively complex, but the defects of the Eulerian method are expected to be overcome under the Lagrangian framework.

In this study, the global sea surface geostrophic flow field provided by satellite data from 1993 to 2019 was used to drive high-resolution (1/32 degree) Lagrangian particles, the trajectory of particles in 180 days was calculated, the Lagrangian eddy with lifetimes of 30, 90 and 180 d was detected based on the Lagrangian-averaged vorticity deviation (LAVD) method, and a global Lagrangian eddy dataset (GLED v1.0) was established; This open-source dataset contains not only the general features (eddy center position, equivalent radius, rotation property, etc.) of eddies, but also the trajectories of particles trapped by eddies over the lifetime. The statistical features of Lagrangian eddies and sea surface height (SSH) eddies were compared, and it is found that the two types of eddies move at similar speeds, but the radius of Lagrangian eddies is only half that of SSH eddies; The reliability of the dataset was also verified by using Argo buoy data. This dataset is of great significance for more accurate diagnosis of the contribution of eddy-carrying transport, and will help understand the role of mesoscale eddies in physical, biological and chemical processes.

The eddy dataset is now publicly available on the Zenodo data platform for free use by researchers. The download address is https://zenodo.org/record/7349753#.ZD-LHexBxz8, and the data processing and visualization algorithm are provided on GitHub (https://github.com/liutongya/GLED).

Earth System Science Data is a top journal in the field of earth systems science, which aims to publish the latest and original high-quality datasets in the field of earth systems science. The latest impact factor is 11.815, and its CiteScore ranks among the top geoscience journals.

The research was jointly supported by the NSFC Youth Fund and the NSFC Major Instrument Program.

Figure 1 Flow chart of Lagrangian eddy dataset

Figure 2 Global LAVD field and detected Lagrangian eddies

Paper Citation:

 Liu, T. and Abernathey, R.: A global Lagrangian eddy dataset based on satellite altimetry, Earth System Science Data, 15, 1765–1778, https://doi.org/10.5194/essd-15-1765-2023, 2023.