Interaction of eddies and jets over the coco topographic rise in the emperor seamount chain

Based on a 15-year record of satellite altimetry observations (2010–2024), the dynamics of mesoscale eddies and a jet current in the vicinity of the Coco Guyot., the largest seamount in the southern part of the Emperor Seamount Chain, were investigated. Using an algorithm for tracking elliptical and hyperbolic points, trajectories of cyclone, anticyclone, and hyperbolic-point centres were obtained, together with their kinematic characteristics, including lifetime, displacement, and trajectory length. A new method for daily mapping of jet regions was developed based on a combination of Lagrangian indicators, namely the distance travelled and the number of revolutions performed by passive tracers. It is shown that the centres of long-lived cyclones and anticyclones (with lifetimes exceeding 10 days) exhibit no statistically significant spatial association with the guyot. In contrast, the occurrence frequency of hyperbolic points displays a pronounced local maximum directly above the seamount, indicating flow deformation induced by topographic interaction. Local eddy generation was identified on the guyot slopes, with cyclones forming preferentially on the upstream side and anticyclones on the downstream side; however, their contribution to the overall eddy statistics is minor. The occurrence frequency of hyperbolic points reaches its maximum when the North Pacific Current jet is displaced northward and its minimum when the jet shifts southward. A persistent annual cycle was detected in the abundance of all identified structures, with no significant interannual trends. At the same time, a pronounced northward shift of the jet current was observed after 2021. The results suggest that the Coco Guyot should be regarded not as a source of long-lived eddies but rather as a topographic modulator of flow deformation. The proposed methods can be readily applied to similar studies in other regions of the World Ocean.