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Coastal Kelvin waves in the presence of a slowly varying topography

Published online by Cambridge University Press:  26 April 2006

Ping Chang
Ping Chang
Affiliation:
The Joint Institute of the Study of the Atmosphere and Oceans, University of Washington, AK-40, Seattle, WA 98195, USA Present address: Department of Oceanography, Texas A&M University. College Station, TX 77843, USA.
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Abstract

The evolution equation is derived for a weakly nonlinear coastal Kelvin wave propagating in slowly varying topography in an f-plane ocean. For weak transverse variations in the topography, the wave evolution is governed by a perturbed Korteweg–de Vries equation. In the absence of transverse variation, wave dispersion vanishes and the evolution equation reduces to a nonlinear advection equation with variable coefficients. As a general property of these equations, the total mass flux associated with the Kelvin wave is not conserved; residual mass must be generated. It is shown by an asymptotic analysis that this residual mass field is in balance with a mean geostrophic current long after the passage of the Kelvin wave. This result is verified using a numerical model. The physical mechanism evolved in the generation of the residual mass can be understood in terms of potential vorticity conservation.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 231 , October 1991 , pp. 303 - 324
Copyright
© 1991 Cambridge University Press

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