[A-CG49] Kuroshio Large Meander

[ACG49-03] Variations of the Kuroshio and Kuroshio Extension meandering paths, as seen by the SWOT altimeter

*Kaoru Ichikawa¹ (1.Research Institute for Applied Mechanics, Kyushu University)

Keywords:Kuroshio axis, SWOT altimeter, detached eddy , meander

In recent years, the Kuroshio to the south of Japan and the Kuroshio Extension to the east of Japan have taken stable significant meandering paths. Some data assimilation models indicate that these meanders sometimes detach from the Kuroshio or the Kuroshio Extension, forming detached eddies, and then the eddies rejoin to form large meanders again. However, not only with in situ observations by ships and drifters, but also with conventional satellite altimeters, the detachment of meanders or changes in the path shapes are difficult to observe. Meanwhile, the SWOT altimeter, which began observations in 2023, can obtain instantaneous spatial distribution of SSH approximately every 10 days, making it suitable for directly capturing the flow path shape and eddy detachments. Therefore, we described the shapes and detachment of the Kuroshio and Kuroshio Extension meandering paths from July 2023 onwards, using SWOT SSH data (version 2.0 Level 3 LR_SSH). In the Kuroshio Extension off the coast of Tohoku, the detachment and merging of eddies occur frequently. On the other hand, although the large meander of the Kuroshio to the south of Japan frequently changes its path shapes partly due to the influence of mesoscale eddies propagating from the east, the meander has never completely detached. Details will be discussed in the presentation.