What the Kuroshio swifts Cape Eluanbi will bring on


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Topographic effects on flow often induce submesoscale and small‐scale processes (e.g., wake flow and barotropic instability) which may grow into submesoscale eddies. Although these physical processes are difficult to observe by our eyeball, the chlorophyll concentration as a tracer visualizes that. The processes underlying the strong Kuroshio encountering a cape at the southernmost tip of Taiwan are examined with satellite‐derived chlorophyll and temperature maps, a drifter trajectory, and realistic model simulations. Results showed that the primary processes are a recirculation in the lee of the cape, further shedding downstream as a train of submesoscale cyclonic eddies. Next, the eddy propagates downstream and catches up to a preexisting eddy. After that, the cyclonic eddies form a corotating system and merge to form a single eddy. These eddies may rise/advect cold and nutrient water and carry the water masses to downstream. Besides, the frontal waves predominate in the growth of barotropic instability in the free shear layer, which may play a secondary process in the headland wake. This work has been published in Journal of Geophysical Research: Oceans. Download the paper at https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JC016123


Cheng, Y.‐H., Chang*, M.‐H., Ko, D. S., Jan, S., Andres, M., Kirincich, A., Yang, Y. J., and Tai, J.‐H. (2020). Submesoscale Eddy and Frontal Instabilities in the Kuroshio Interacting with a Cape South of Taiwan. Journal of Geophysical Research: Oceans, 124, e2020JC016123. https://doi.org/10.1029/2020JC016123 (*Corresponding author)

Figure 1. A chlorophyll‐a concentration snapshot off southeast Taiwan. The geostrophic current velocities from satellite altimeters derived from the absolute dynamic topography are shown in white arrows.