Equatorial Waves in the Presence of the Equatorial Undercurrent

S. G. H. Philander Geophysical Fluid Dynamics Program, Princeton University, Princeton, NJ 08540

Search for other papers by S. G. H. Philander in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Because of the narrow region over which it has high speeds, the Equatorial Undercurrent has little effect on long waves with large phase speeds, such as long Kelvin and equatorially trapped inertia-gravity modes with equivalent depths ≳30 cm. The Rossby branch of the Rossby-gravity family, and the gravest Rossby modes, have phase velocities comparable to the maximum speed of the Undercurrent and are significantly modified by this current. Meanders of the Undercurrent that are due to superimposed neutral (non-amplifying) waves must have westward phase propagation; standing or eastward traveling meanders are possible only if the Equatorial Undercurrent is unstable.

Abstract

Because of the narrow region over which it has high speeds, the Equatorial Undercurrent has little effect on long waves with large phase speeds, such as long Kelvin and equatorially trapped inertia-gravity modes with equivalent depths ≳30 cm. The Rossby branch of the Rossby-gravity family, and the gravest Rossby modes, have phase velocities comparable to the maximum speed of the Undercurrent and are significantly modified by this current. Meanders of the Undercurrent that are due to superimposed neutral (non-amplifying) waves must have westward phase propagation; standing or eastward traveling meanders are possible only if the Equatorial Undercurrent is unstable.

Save