On the connection between eddy impingement east of Taiwan and Kuroshio intrusion into South China Sea

Using absolute dynamic topography and satellite altimeter eddy tracking data, the intrusion of the Kuroshio caused by the impingement of mesoscale cyclone eddies east of Taiwan into the northern South China Sea (NSCS) through the Luzon Strait was studied. Between 1993 and 2021, a total of 12 such cases were identified. Six of them occurred when the Kuroshio upstream (east of Luzon) strengthened and the Kuroshio downstream (east of Taiwan) weakened. A composite analysis of all cases shows that the average time from when a mesoscale cyclonic eddy impinges the Kuroshio east of Taiwan to when the NSCS reaches maximum negative vorticity is about 28 days. When the Kuroshio upstream strengthens and downstream weakens, the negative vorticity of the NSCS west of the Luzon Strait increases by 45% compared with normal conditions. The duration of the interaction between the Kuroshio and the mesoscale cyclonic eddy east of Taiwan is 28 days, compared with the normal 41 days.