We thank two anonymous reviewers and Editor Mike Spall, whose comments improved the manuscript. YLC is supported by National Science Council under NSC 101-2119-M-003-005. Startup funding from National Taiwan Normal University is acknowledged. Support for LYO from Taiwan’s Foundation for the Advancement of Outstanding Scholarship and the National Science Council under fund NSC 100-2119-M-008-036-MY3 is acknowledged.
Aoki, Y., , T. Suga, , and K. Hanawa, 2002: Subsurface subtropical fronts of the North Pacific as inherent boundaries in the ventilated thermocline. J. Phys. Oceanogr., 32, 2299–2311.
Blumberg, A. F., , and G. L. Mellor, 1987: A description of a three-dimensional coastal ocean circulation model. Three-Dimensional Coastal Ocean Models, Coastal Estuarine Sci., Vol. 4, Amer. Geophys. Union, 1–16.
Boccaletti, G., , R. Ferrari, , and B. Fox-Kemper, 2007: Mixed layer instabilities and restratification. J. Phys. Oceanogr., 37, 2228–2250.
Chang, Y.-L., , and L.-Y. Oey, 2011: Frontal circulation induced by up-front and coastal downwelling winds. Ocean Dyn., 61, 1345–1368.
Chang, Y.-L., , and L.-Y. Oey, 2012: The Philippines–Taiwan Oscillation: Monsoonlike interannual oscillation of the subtropical–tropical western North Pacific wind system and its impact on the ocean. J. Climate, 25, 1597–1618.
Chang, Y.-L., , L.-Y. Oey, , C.-R. Wu, , and H.-F. Lu, 2010: Why are there upwellings on the northern shelf of Taiwan under northeasterly winds? J. Phys. Oceanogr., 40, 1405–1417.
Chelton, D. B., , M. G. Schlax, , and R. M. Samelson, 2011: Global observations of nonlinear mesoscale eddies. Prog. Oceanogr., 91, 167–216.
D’Asaro, E., , C. Lee, , L. Rainville, , R. Harcourt, , and L. Thomas, 2011: Enhanced turbulence and energy dissipation at ocean fronts. Science, 332, 318–322.
Descamps, L., , D. Ricard, , A. Joly, , and P. Arbogast, 2007: Is a real cyclogenesis case explained by generalized linear baroclinic instability? J. Atmos. Sci., 64, 4287–4308.
Gill, A. E., 1982: Atmosphere–Ocean Dynamics. Academic, 662 pp.
Gill, A. E., , J. S. A. Green, , and A. J. Simmons, 1974: Energy partition in the large-scale ocean circulation and the production of mid-ocean eddies. Deep-Sea Res., 21, 499–528.
Isern-Fontanet, J., , E. García-Ladona, , and J. Font, 2006: Vortices of the Mediterranean Sea: An altimetric perspective. J. Phys. Oceanogr., 36, 87–103.
Isobe, A., 2008: Recent advances in ocean circulation research on the Yellow Sea and East China Sea shelves. J. Oceanogr., 64, 569–584.
Kobashi, F., , and H. Kawamura, 2002: Seasonal variation and instability nature of the North Pacific Subtropical Countercurrent and the Hawaiian Lee Countercurrent. J. Geophys. Res., 107, 3185, doi:10.1029/2001JC001225.
Kobashi, F., , and A. Kubokawa, 2012: Review on North Pacific Subtropical Countercurrents and subtropical fronts: Role of mode waters in ocean circulation and climate. J. Oceanogr., 68, 21–43.
Kobashi, F., , and S.-P. Xie, 2012: Interannual variability of the North Pacific Subtropical Countercurrent: Role of local ocean–atmosphere interaction. J. Oceanogr., 68, 113–126.
Kobashi, F., , H. Mitsudera, , and S.-P. Xie, 2006: Three subtropical fronts in the North Pacific: Observational evidence for mode water-induced subsurface frontogenesis. J. Geophys. Res., 111, C09033, doi:10.1029/2006JC003479.
Levitus, S., , and T. P. Boyer, 1994: Temperature. Vol. 4, World Ocean Atlas 1994, NOAA Atlas NESDIS 4, 117 pp.
Niiler, P. P., , N. A. Maximenko, , G. G. Panteleev, , T. Yamagata, , and D. B. Olson, 2003: Near-surface dynamical structure of the Kuroshio Extension. J. Geophys. Res., 108, 3193, doi:10.1029/2002JC001461.
Nitani, H., 1972: Beginning of the Kuroshio. Kuroshio: Its Physical Aspects, H. Stommel and K. Yoshida, Eds., University of Tokyo Press, 129–163.
Oey, L.-Y., 2008: Loop current and deep eddies. J. Phys. Oceanogr.,38, 1426–1449.
Oey, L.-Y., , and P. Chen, 1992: A model simulation of circulation in the northeast Atlantic shelves and seas. J. Geophys. Res., 97 (C12), 20 087–20 115.
Oey, L.-Y., , Y.-L. Chang, , Y.-C. Lin, , M.-C. Chang, , F.-H. Xu, , and H.-F. Lu, 2013: ATOP—The Advanced Taiwan Ocean Prediction System based on the mpiPOM. Part 1: Model descriptions, analyses and results. Terr. Atmos. Oceanic Sci., 24, 137–158.
Okubo, A., 1970: Horizontal dispersion of floatable particles in the vicinity of velocity singularities such as convergences. Deep-Sea Res., 17, 445–454.
Pedlosky, J., 1979: Geophysical Fluid Dynamics. Springer-Verlag, 624 pp.
Polton, J. A., , and S. E. Belcher, 2007: Langmuir turbulence and deeply penetrating jets in an unstratified mixed layer. J. Geophys. Res., 112, C09020, doi:10.1029/2007JC004205.
Qiu, B., 1999: Seasonal eddy field modulation of the North Pacific subtropical countercurrent: TOPEX/Poseidon observations and theory. J. Phys. Oceanogr., 29, 2471–2486.
Qiu, B., , and T. Joyce, 1992: Interannual variability in the mid- and low-latitude western North Pacific. J. Phys. Oceanogr., 22, 1062–1079.
Qiu, B., , and S. Chen, 2010: Interannual variability of the North Pacific Subtropical Countercurrent and its associated mesoscale eddy field. J. Phys. Oceanogr., 40, 213–225.
Qiu, B., , and S. Chen, 2013: Concurrent decadal mesoscale eddy modulations in the western North Pacific subtropical gyre. J. Phys. Oceanogr., 43, 344–358.
Roemmich, D., , and J. Gilson, 2001: Eddy transport of heat and thermocline waters in the North Pacific: A key to interannual/decadal climate variability? J. Phys. Oceanogr., 31, 675–687.
Smagorinsky, J., 1963: General circulation experiments with the primitive equations. I: The basic experiment. Mon. Wea. Rev., 91, 99–164.
Taft, B. A., 1972: Characteristics of the flow of the Kuroshio south of Japan. Kuroshio: Its Physical Aspects, H. Stommel and K. Yoshida, Eds., University of Tokyo Press, 165–216.
Toole, J., , R. Millard, , Z. Wang, , and S. Pu, 1990: Observations of the Pacific North Equatorial Current bifurcation at the Philippine coast. J. Phys. Oceanogr., 20, 307–318.
Tulloch, R., , J. Marshall, , C. Hill, , and K. S. Smith, 2011: Scales, growth rates, and spectral fluxes of baroclinic instability in the ocean. J. Phys. Oceanogr., 41, 1057–1076.
Uda, M., , and K. Hasunuma, 1969: The eastward subtropical countercurrent in the western North Pacific Ocean. J. Oceanogr. Soc. Japan, 25, 201–210.
White, W. B., , K. Hasunuma, , and H. Solomon, 1978: Large-scale seasonal and secular variability of the subtropical front in the western North Pacific from 1954 to 1974. J. Geophys. Res., 83 (C9), 4531–4544.
Wijffels, S. E., , M. M. Hall, , T. M. Joyce, , D. J. Torres, , P. Hacker, , and E. Firing, 1998: Multiple deep gyres of the western North Pacific: A WOCE section along 149°E. J. Geophys. Res., 103 (C6), 12 985–13 009.
Yamanaka, G., , H. Ishizaki, , M. Hirabara, , and I. Ishikawa, 2008: Decadal variability of the subtropical front of the western North Pacific in an eddy-resolving ocean general circulation model. J. Geophys. Res., 113, C12027, doi:10.1029/2008JC005002.
Yoshida, K., , and T. Kidokoro, 1967: A subtropical countercurrent in the North Pacific—An eastward flow near the Subtropical Convergence. J. Oceanogr. Soc. Japan, 23, 88–91.
Zhai, X., , R. J. Greatbatch, , and J. D. Kohlmann, 2008: On the seasonal variability of eddy kinetic energy in the Gulf Stream region. Geophys. Res. Lett., 35, L24609, doi:10.1029/2008GL036412.
Equations for a spatially and temporally variable δE can be derived (Chang and Oey 2011), but the added complications are not warranted in the present case.
Here, the notation Corr(A, B, lags) is the lagged correlation coefficient between A and B with lags in months, positive (negative) if A leads (lags) B. Unless otherwise stated, all quoted correlations are above the 95% significance level.