We examine velocity structure and variability across the Kuroshio east of Luzon and Taiwan using two years of Seaglider observations. The Kuroshio exhibits a single velocity maximum south of Luzon Strait, strengthened downstream. It is occasionally accompanied by a second velocity maximum, and the two together form a dual-core structure east of Taiwan. Two possible mechanisms are responsible for the dual-core phenomenon. One is attributed to intrusion of the Kuroshio into the South China Sea through Luzon Strait, which occurs normally during persistent northeasterlies in winter. The streamline diffluence across the strait during the Kuroshio’s westward intrusions and subsequent shaping of the boundary current through interaction with a quasi-permanent anticyclonic recirculation east of Taiwan favors the appearance of the offshore velocity maximum. The other possible mechanism is related to the dissipation of westward-propagating mesoscale anticyclonic eddies. As the impinging eddy deforms and is eventually dissipated along the Kuroshio’s eastern flank, the northward flow contiguous to the western half of this eddy is enhanced, causing an offshore core downstream. Glider-observed θ–S properties in the dual cores indicate different water masses are mixing, consistent with two different mechanisms causing the dual cores.

Yang, K.-C., J. Wang, C.M. Lee, B. Ma, R.-C. Lien, S. Jan, Y.J. Yang, and M.-H. Chang. 2015. Two mechanisms cause dual velocity maxima in the Kuroshio east of Taiwan. Oceanography 28(4):64–73, https://doi.org/10.5670/oceanog.2015.82.

Centurioni, L.R., P.P. Niller, and D.K. Lee. 2004. Observations of inflow of Philippine Sea surface water into the South China Sea through the Luzon Strait. Journal of Physical Oceanography 34:113–121, https://doi.org/10.1175/1520-0485(2004)034<0113:OOIOPS>2.0.CO;2.

Chen, C.T.A. 2005. Tracing tropical and intermediate waters from the South China Sea to the Okinawa Trough and beyond. Journal of Geophysical Research 110, C05012, https://doi.org/10.1029/2004JC002494.

Chern, C.-S., S. Jan, and J. Wang. 2010. Numerical study of mean flow patterns in the South China Sea and the Luzon Strait. Ocean Dynamics 60:1,047–1,059, https://doi.org/10.1007/s10236-010-0305-3. 

Chern, C.-S., and J. Wang. 1998. A numerical study of the summertime flow around the Luzon Strait. Journal of Oceanography 54:53–64, https://doi.org/10.1007/BF02744381.

Cushman-Roisin, B. 1994. Introduction to Geophysical Fluid Dynamics. Prentice-Hall, New Jersey, 320 pp.

Ducet, N., P.Y. Le Traon, and G. Reverdin. 2000. Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. Journal of Geophysical Research 105:19,477–19,498, https://doi.org/10.1029/2000JC900063. 

Eriksen, C.C., T.J. Osse, R.D. Light, T. Wen, T.W. Lehman, P.L. Sabin, J.W. Ballard, and A.M. Chiodi. 2001. Seaglider: A long-range autonomous underwater vehicle for oceanographic research. IEEE Journal of Oceanic Engineering 26:424–436, https://doi.org/​10.1109/48.972073. 

Farris, A., and M. Wimbush. 1996. Wind-induced Kuroshio intrusion into the South China Sea. Journal of Oceanography 52:771–784, https://doi.org/10.1007/BF02239465. 

Hsin, Y.-C., C.-R. Wu, and P.-T. Shaw. 2008. Spatial and temporal variations of the Kuroshio east of Taiwan, 1982–2005: A numerical study. Journal of Geophysical Research 113, C04002, https://doi.org/10.1029/2007JC004485. 

Jan, S., Y.J. Yang, J. Wang, V. Mensah, T.-H. Kuo, M.-D. Chiou, C.-S. Chern, M.-H. Chang, and H. Chien. 2015. Large variability of the Kuroshio at 23.75°N east of Taiwan. Journal of Geophysical Research 120:1,825–1,840, https://doi.org/​10.1002/2014JC010614. 

Kuo, Y.-C., and C.-S. Chern. 2011. Numerical study on the interactions between a mesoscale eddy and a western boundary current. Journal of Oceanography 67:263–272, https://doi.org/​10.1007/s10872-011-0026-3.

Liang, W.-D., T.Y. Tang, Y.J. Yang, M.T. Ko, and W.-S. Chuang. 2003. Upper-ocean currents around Taiwan. Deep Sea Research Part I 50:1,085–1,105, https://doi.org/10.1016/S0967-0645(03)00011-0. 

Lien, R.-C., B. Ma, Y.-H. Cheng, C.-R. Ho, B. Qiu, C.M. Lee, and M.-H. Chang. 2014. Modulation of Kuroshio transport by mesoscale eddies at the Luzon Strait entrance. Journal of Geophysical Research 119:2,129–2,142, https://doi.org/​10.1002/2013JC009548. 

Lien, R.-C., B. Ma, C.M. Lee, T.B. Sanford, V. Mensah, L.R. Centurioni, B.D. Cornuelle, G. Gopalakrishnan, A.L. Gordon, M.-H. Chang, and others. 2015. The Kuroshio and Luzon Undercurrent east of Luzon Island. Oceanography 28(4):54–63, https://doi.org/10.5670/oceanog.2015.81.

Mensah, V., S. Jan, M.-D. Chiou, T.-H. Kuo, and R.-C. Lien. 2014. Evolution of the Kuroshio tropical water from the Luzon Strait to the east of Taiwan. Deep Sea Research Part I 86:68–81, https://doi.org/10.1016/j.dsr.2014.01.005. 

Metzger, E.J., and H.E. Hurlburt. 2001. The nondeterministic nature of Kuroshio penetration and eddy shedding in the South China Sea. Journal of Physical Oceanography 31:1,712–1,732, https://doi.org/10.1175/1520-0485(2001)031​<1712:TNNOKP>2.0.CO;2.

Nitani, H. 1972. Beginning of the Kuroshio. Pp. 129–163 in Kuroshio, Its Physical Aspects. H. Stommel and K. Yoshida, eds, University of Tokyo Press, Tokyo.

Pickard, G.L., and W.J. Emery. 1993. Descriptive Physical Oceanography: An Introduction, 5^th ed. Pergamon Press, 320 pp.

Rudnick, D.L., S. Jan, L. Centurioni, C.M. Lee, R.-C. Lien, J. Wang, D.-K. Lee, R.-S. Tseng, Y.Y. Kim, and C.-S. Chern. 2011. Seasonal and mesoscale variability of the Kuroshio near its origin. Oceanography 24(4):52–63, https://doi.org/​10.5670/oceanog.2011.94.

Saucier, W.J. 1955. Principles of Meteorological Analysis. University of Chicago Press, 438 pp.

Yuan, D., W. Han, and D. Hu. 2006. Surface Kuroshio path in the Luzon Strait area derived from satellite remote sensing data. Journal of Geophysical Research 111, C11007, https://doi.org/10.1029/2005JC003412. 

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