Observing subsurface changes of two anticyclonic eddies passing over the Izu‐Ogasawara Ridge. Issue 4 (18th February 2017) - Xu, Lixiao
Abstract: Eddy‐bathymetry interactions are common in the ocean, but the full evolution of the interaction is difficult to observe below the surface. Using 17 Iridium Argo floats, we continually track two anticyclonic eddies (AEs) in the North Pacific that migrate westward and encounter the Izu‐Ogasawara Ridge. Based on over 5000 Argo profiles following the two AEs, this study presents the first detailed descriptions of changes in eddy vertical structure and diapycnal mixing as the two AEs pass the Ridge. There, we find that isopycnals dome up and the eddy diameter increases, while the diapycnal mixing is enhanced—to the order of 10 −4 m 2 s −1 or larger, in comparison with an ambient of 10 −5 m 2 s −1 . The enhanced mixing around the AE center in the upper −1000 m appears where the underlying bathymetry is shallower than −4000 m and is mainly sustained by tidally generated internal waves. Key Points: Changes of two anticyclonic eddies passing over the Izu‐Ogasawara Ridge are continually tracked by 17 Argo floats The eddy vertical structure and diapycnal mixing in the upper −1000 m could "remote sense" topography change below −3000 m Enhanced mixing around the AEs over the ridge is closely related to bathymetry and is mainly sustained by tidally generated internal waves