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On the reflection of the equatorial waves at eastern ocean boundaries

On the reflection of the equatorial waves at eastern ocean boundaries
On the reflection of the equatorial waves at eastern ocean boundaries

Observational and theoretical studies have indicated that much of the oceanographic variability along the eastern ocean boundaries, for example that associated with El Niñ, is remotely forced. The remotely forced motion along these boundaries originates from the reflection of low frequency baroclinic Kelvin waves on the equatorial boundary. At the equator, part of the incoming Kelvin wave energy is reflected in the form of westward propagating Rossby waves and the remainder of the energy is divided between northward and southward propagating coastal Kelvin waves. Previous analytical results have shown the strong dependence of both coastline slope and incident wave frequency on the wave reflection at the eastern boundary.

A baroclinic shallow water model is developed to explore the behaviour of the baroclinic equatorial Kelvin waves when they reach different eastern oceanic boundaries. The large latitudinal extent used in the numerical domain permits consideration of the response at both equatorial and mid-latitudes. Previous analytical studies in this field have always excluded some effects, such as viscosity and non linearities, and employed approximations (equatorial β-plane, low frequency wave, meridional boundaries, for example) to the governing equations in order to solve them analytically. Numerical solutions, however, can be obtained without these approximations and the real ocean is viscous, non linear and has nonmeridional boundaries.

The energy flux results indicate that the nonlinear effects can be regarded as negligible when considering reflection of equatorial waves at eastern boundary, whereas the viscous effects are very important. The influence of the coastline geometry and the incident wave period, is found to be more important for the westward energy flux than for the poleward flux.

University of Southampton
Soares, Jacyra Ramos
e1d01ea3-2e1b-453c-8814-394436c77296
Soares, Jacyra Ramos
e1d01ea3-2e1b-453c-8814-394436c77296

Soares, Jacyra Ramos (1993) On the reflection of the equatorial waves at eastern ocean boundaries. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

Observational and theoretical studies have indicated that much of the oceanographic variability along the eastern ocean boundaries, for example that associated with El Niñ, is remotely forced. The remotely forced motion along these boundaries originates from the reflection of low frequency baroclinic Kelvin waves on the equatorial boundary. At the equator, part of the incoming Kelvin wave energy is reflected in the form of westward propagating Rossby waves and the remainder of the energy is divided between northward and southward propagating coastal Kelvin waves. Previous analytical results have shown the strong dependence of both coastline slope and incident wave frequency on the wave reflection at the eastern boundary.

A baroclinic shallow water model is developed to explore the behaviour of the baroclinic equatorial Kelvin waves when they reach different eastern oceanic boundaries. The large latitudinal extent used in the numerical domain permits consideration of the response at both equatorial and mid-latitudes. Previous analytical studies in this field have always excluded some effects, such as viscosity and non linearities, and employed approximations (equatorial β-plane, low frequency wave, meridional boundaries, for example) to the governing equations in order to solve them analytically. Numerical solutions, however, can be obtained without these approximations and the real ocean is viscous, non linear and has nonmeridional boundaries.

The energy flux results indicate that the nonlinear effects can be regarded as negligible when considering reflection of equatorial waves at eastern boundary, whereas the viscous effects are very important. The influence of the coastline geometry and the incident wave period, is found to be more important for the westward energy flux than for the poleward flux.

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Published date: 1993

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Local EPrints ID: 462422
URI: http://eprints.soton.ac.uk/id/eprint/462422
PURE UUID: b59c4dcf-5baa-490d-9e8d-7df506a29fe7

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Date deposited: 04 Jul 2022 19:07
Last modified: 16 Mar 2024 18:55

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Author: Jacyra Ramos Soares

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