Reflection of equatorial Kelvin waves at eastern ocean boundaries Part II: Pacific and Atlantic Oceans

J Soares,N C Wells,I Wainer

doi:10.1007/s00585-999-0827-5

Abstract

Abstract. The effect of viscosity, non linearities, incident wave period and realistic eastern coastline geometry on energy fluxes are investigated using a shallow water model with a spatial resolution of 1/4 degree in both meridional and zonal directions. Equatorial and mid-latitude responses are considered. It is found that (1) the influence of the coastline geometry and the incident wave period is more important for the westward energy flux than for the poleward flux, and (2) the effect of the inclination of the eastern ocean boundary on the poleward energy flux, for the Pacific and Atlantic Oceans, decline as the period of the incident wave increases. Furthermore, the model simulations suggest that the poleward energy fluxes from meridional boundaries give plausible results for motions of seasonal and annual periods. For comparatively shorter periods, a realistic coastline geometry has to be included for more accurate results. It is recommended that any numerical model involving the reflection of baroclinic Rossby waves (of intraseasonal, seasonal or annual periods) on the eastern Pacific or Atlantic Oceans, should consider the effect of the coastline geometry in order to improve the accuracy of the results.Key words. Oceanography: general (climate and interannual variability; equatorial oceanography). Oceanography: physical (eastern boundary currents).

Highlights

Equatorial Kelvin waves are thought to occur over a wide range of frequencies
The low-frequency response of sea level on the eastern ocean boundaries can be subdivided for linear purposes into two independent constituents (1) the remotely forced part, i.e., that which is the result of an equatorial Kelvin wave incident on the boundary, and (2) the locally forced part
The main aim of this study is to investigate the behavior of the low-frequency baroclinic equatorial Kelvin waves when they reach the Paci®c and Atlantic Ocean eastern coasts

Summary

Introduction

Equatorial Kelvin waves are thought to occur over a wide range of frequencies. Sea level records from El NinÄ o years reveal that sustained periods of high sea levelCorrespondence to: J. Equatorial Kelvin waves are thought to occur over a wide range of frequencies. The low-frequency response of sea level on the eastern ocean boundaries can be subdivided for linear purposes into two independent constituents (1) the remotely forced part, i.e., that which is the result of an equatorial Kelvin wave incident on the boundary, and (2) the locally forced part. The latter is due to the longshore component of the wind (Bigg and Gill, 1986)

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