Generation Process of Mesoscale Eddies Southwest of Taiwan Island influenced by the Kuroshio Intrusion

Abstract

Based on satellite altimeter observations from 1993 to 2024 and a high-resolution regional ocean model, this study examines how Kuroshio intrusion pathways through the Luzon Strait regulate mesoscale eddy generation southwest of Taiwan Island. Long-term statistics show that eddy occurrence and polarity are closely linked to the intrusion pathway: the leaking pathway produces the most eddies, the looping pathway favors cyclonic eddies, and the leaking and leaping pathways are more often associated with anticyclonic eddies. In the representative 2011 cases, kinetic energy transfer from the mean flow to the eddy field is the dominant energy source during local eddy generation, with the component associated with cross-stream variation in mean flow contributing most to kinetic energy conversion. Three-dimensional energetics diagnostics further show that the cyclonic eddy (CE1) generated under the looping pathway is characterized by stronger upper-ocean barotropic instability, deeper extension of eddy kinetic energy, and a more concentrated upper-ocean energy structure. In contrast, the anticyclonic eddy (ACE2) generated under the leaking pathway exhibits a mixed barotropic and baroclinic instability regime with a more vertically uniform energy distribution. The robustness of these mechanistic results should be further evaluated using additional events and higher-resolution simulations.