The Azimuth Project
Oceanic Rossby wave



Oceanic Rossby waves are very low-frequency waves in the ocean’s surface and thermocline. At the ocean’s surface they are only 5 centimeters high, but hundreds of kilometers across. They move at about 10 centimeters/second, requiring months to years to cross the ocean! The surface waves are mirrored by waves in the thermocline, which are much larger, 10-50 meters in height. When the surface goes up, the thermocline goes down.

In some theories of the ENSO cycle, Oceanic Rossby waves play an important role in triggering El Niño events. For more, see ENSO.


You can watch a 3-year long movie of oceanic Rossby waves, and also read more about them here:

These authors have investigated the characteristics of low-frequency, large-scale Rossby waves using data from the TOPEX/Poseidon satellite. Their movie shows the sea level in the Pacific, filtered in a specific way to make the Rossby waves visible:

A westward-propagating Rossby wave trough centered on the equator and extending to mid-latitudes in both hemispheres can be seen in the Pacific Ocean in the April 13, 1993 frame. The refracted shape that is characteristic of Rossby waves is due to the latitudinal variation of phase speed. In the July 31, 1993 frame, this Rossby wave trough has impinged on the western boundary of the Pacific and an equatorial Kelvin wave trough centered at about 140 W has propagated rapidly eastward more than half way across the Pacific, splitting a newly formed Rossby wave crest that has propagated westward from South America.

Also see Equatorial Kelvin wave.

category: climate, oceans