META4.0: a new mesoscale eddy network atlas derived from altimetry

Abstract. This study introduces the new global Mesoscale Eddy Trajectory Atlases (META4.0), which provide eddy detections, trajectories, and interaction networks derived from satellite altimetry. Eddy detection relies on the pyeddytracker (PET) algorithm (Mason et al., 2014), further optimized by Pegliasco et al. (2022), and represents a substantial improvement over the previous META3.2 product (SSALTO/DUACS, distributed by AVISO+ with CNES support).

The main advance of META4.0 is the explicit identification of eddy merging and splitting events. By combining grouping, which links detections across consecutive days, and segmentation, which tracks continuity through interaction events, trajectories are organized into networks of interconnected eddies. This network-based representation complements the classical single-trajectory view of eddy life cycles by explicitly accounting for eddy interactions.

The paper presents both diagnostic tools designed to explore individual eddy networks (e.g., timelines, spatial trajectories, and eddy properties such as effective radius or shape error) and the results of a global statistical analysis over more than three decades. These analyses provide new insights into network properties, eddy lifetimes, and the spatial and temporal distribution of merging and splitting events. Clustering analyses reveal recurrent interaction patterns and identify regions where eddy networks are particularly active. Independent datasets, including sea surface temperature and chlorophyll concentration, are used for qualitative validation of selected events. Finally, Lagrangian advection of synthetic particles highlights coherent forward and backward transport signatures associated with interaction events, providing a physical validation of the reconstructed networks.

Overall, META4.0 offers a novel and physically consistent framework to characterize mesoscale eddy interactions and to better understand their role in shaping ocean dynamics.