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Kelvin wave From Wikipedia, the free encyclopedia • Find out more about navigating Wikipedia and finding information • Jump to: navigation, search A Kelvin wave is a wave in the ocean or atmosphere that balances the Earth's Coriolis force against a topographic boundary such as a coastline. A feature of a Kelvin wave is that it is non-dispersive, i.e., the phase speed of the wave crests is equal to the group speed of the wave energy for all frequencies. This means that it retains its shape in the alongshore direction over time. A Kelvin Wave (fluid dynamics) is also a long scale perturbation mode of a vortex in superfluid dynamics. Kelvin waves in the ocean always propagate with the shoreline on the right in the northern hemisphere, and with the shoreline on the left in the southern hemisphere. [edit] Equatorial Kelvin wave An equatorial Kelvin wave is a special type of Kelvin wave in which the equator acts analogously to a topographic boundary for both the Northern and Southern Hemispheres. When the motion at the equator is to the east, any deviation toward the north is brought back toward the equator because the Coriolis force acts to the right of the direction of motion in the Northern Hemisphere, and any deviation to the south is brought back toward the equator because the Coriolis force acts to the left of the direction of motion in the Southern Hemisphere. Note that for motion toward the west, the Coriolis force would not restore a northward or southward deviation back toward the equator; thus, equatorial Kelvin waves are only possible for eastward motion. Both atmospheric and oceanic equatorial Kelvin waves play an important role in the dynamics of El Nino-Southern Oscillation, by transmitting changes in conditions in the Western Pacific to the Eastern Pacific. Equatorial Kelvin waves are often associated with anomalies in surface wind stress. The plot below shows wind stress anomalies (deviations from "normal" winds) on the left and on the right the depth at which the water is 20°C known as the 20°C isotherm depth, which defines the lower limit of the surface layer of warm water). Positive (eastward) anomalies in wind stress in the central Pacific excite positive anomalies in 20°C isotherm depth which propagate to the east as equatorial Kelvin waves. Image:Tao_buoy_Kelvin.gif [edit] External links * Overview of Kelvin waves from the American Meteorological Society. * US Navy page on Kelvin waves. * Slideshow at utexus.edu about Kelvin waves. This climatology/meteorology-related article is a stub. You can help Wikipedia by expanding it. This oceanography article is a stub. You can help Wikipedia by expanding it. Retrieved from "http://en.wikipedia.org/wiki/Kelvin_wave" Categories: Physical oceanography | Tropical meteorology | Atmospheric dynamics | Atmospheric science stubs | Oceanography stubs Views * Article * Discussion * Edit this page * History Personal tools * Log in / create account Navigation * Main Page * Contents * Featured content * Current events * Random article Interaction * About Wikipedia * Community portal * Recent changes * Contact Wikipedia * Donate to Wikipedia * Help Search Toolbox * What links here * Related changes * Upload file * Special pages * Printable version * Permanent link * Cite this page Languages * Deutsch * Français * Italiano * ‪Norsk (bokmål)‬ * ‪Norsk (nynorsk)‬ * Polski * Svenska Powered by MediaWiki Wikimedia Foundation * This page was last modified on 9 May 2008, at 20:06. * All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax-deductible nonprofit charity. * Privacy policy * About Wikipedia * Disclaimers Help us provide free content to the world by donating today!