Interannual to Decadal Variations in Different Kuroshio Intrusion Paths in the Luzon Strait Based on Long-Term Reanalysis Data

Different Kuroshio intrusion paths in the Luzon Strait show diverse influences on water mass exchange between the Pacific Ocean and South China Sea (SCS). However, the interannual to decadal variabilities in different Kuroshio intrusion paths in the Luzon Strait are still poorly understood. In this study, the Kuroshio paths in the Luzon Strait are identified on the basis of a modified identification method and long-term GLORYS12V1 outputs between 1993 and 2020. The occurrence probabilities of the looping, leaking, and leaping paths are 25.1%, 43.1%, and 31.8%, respectively. Seasonally, the looping and leaking paths predominantly occur in winter and winter half-year, respectively. On the interannual timescale, the looping path tends to be stronger (weaker) during La Niña (El Niño) winters because the strengthened (weakened) northeast monsoon winds provide more (less) negative relative vorticity southwest of Taiwan, which helps generate a stronger (weaker) Kuroshio looping path. For the leaking path, its contribution to the upper-layer Luzon Strait transport (LST) exceeds 57.8%. The leaking path and the upper-layer LST are both stronger (weaker) during the positive (negative) phase of the Pacific Decadal Oscillation (PDO). The negative sea surface height anomaly northwest of Luzon Island through the clockwise propagation of coastal Kelvin waves along the Philippines and the weakened upstream Kuroshio strength east of Luzon Island both favor the generation of a stronger leaking path during the positive phase of the PDO. The above analyses enhance our knowledge of Kuroshio behaviors in the Luzon Strait and help better understand the multiscale dynamics in the SCS.