We thank Jay McCreary for suggesting the perturbation approach, Dennis Moore for guidance and inspiration, and Tom Farrar for many helpful discussions. We also thank Mike McPhaden and two anonymous reviewers for excellent comments that improved the quality of the paper. The work was supported by NASA Grants NNG05GN98G and NNX10AO93G.
Boyd, J. P., 1978: The effects of latitudinal shear on equatorial waves. Part II: Applications to the atmosphere. J. Atmos. Sci., 35, 2259–2267.
Chelton, D. B., R. A. deSzoeke, M. G. Schlax, K. El Naggar, and N. Siwertz, 1998: Geographical variability of the first baroclinic Rossby radius of deformation. J. Phys. Oceanogr., 28, 433–460.
Chelton, D. B., M. G. Schlax, J. M. Lyman, and G. C. Johnson, 2003: Equatorially trapped Rossby waves in the presence of meridionally sheared baroclinic flow in the Pacific Ocean. Prog. Oceanogr., 56, 323–380.
Johnson, G. C., B. M. Sloyan, W. S. Kessler, and K. E. McTaggart, 2002: Direct measurements of upper ocean currents and water properties across the tropical Pacific during the 1990s. Prog. Oceanogr., 52, 31–61.
McPhaden, M. J., and R. A. Knox, 1979: Equatorial Kelvin and inertio-gravity waves in a zonal shear flow. J. Phys. Oceanogr., 9, 263–277.
Moore, D. W., and S. G. H. Philander, 1977: Modeling of the tropical ocean circulation. The Sea, E. D. Goldberg, Ed., Marine Modeling, Vol. 6, John Wiley & Sons 319–361.
Ripa, P., 1982: Nonlinear wave–wave interactions in a one-layer reduced-gravity model on the equatorial β plane. J. Phys. Oceanogr., 12, 97–111.
Ripa, P., and S. G. Marinone, 1983: The effect of zonal currents on equatorial waves. Hydrodynamics of the Equatorial Ocean, C. J. C. Nihoul, Ed., Elsevier, 291–317.
Zheng, Q., X.-H. Yan, and C.-R. Ho, 1994: The effects of shear flow on propagation of Rossby waves in the equatorial oceans. J. Phys. Oceanogr., 24, 1680–1686.