Equatorial kelvin waves

From Glossary of Meteorology
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equatorial Kelvin wave

An eastward propagating wave centered about the equator with zonal but no meridional velocity.

The zonal velocity has a Gaussian meridional structure centered about the equator with standard deviation equal to the equatorial Rossby radius of deformation. In the shallow water approximation the waves are nondispersive with frequency
in which k is the along-boundary wavenumber, and the phase speed
with g the acceleration of gravity and H the mean fluid depth. The equatorial Rossby radius of deformation in this case is
in which β is the meridional gradient of the Coriolis parameter at the equator. A Kelvin wave propagating equatorward along the western boundary of an ocean basin can generate an equatorial Kelvin wave when reaching the equator. Upon reaching the eastern boundary of an ocean basin, an equatorial Kelvin wave can generate a coastal Kelvin wave propagating poleward along the eastern boundary of the ocean basin.

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