Warm water creeps into otherwise calm central Pacific
06 June 2018
After a mild La Niña late last year, temperatures, convection and rainfall rates in the equatorial Pacific Ocean returned to normal by early April of this year. An 09 April image of sea level height from the U.S./European Jason-3 satellite mission showed most of the ocean at neutral heights. But by the beginning of May, high sea levels began to build up in the Central Pacific. In the tropics, high sea levels are usually caused by a layer of warm water at or below the surface.
This patch of high sea level is slowly traveling eastward through the tropical Pacific Ocean along the equator. Known as a downwelling Kelvin wave, this type of signal is often a precursor to an El Niño event.
Image credit: NASA/JPL-Caltech - Left, in April, the Jason-3 satellite shows most of the Pacific Ocean at neutral heights (green). In May, a Kelvin wave (red) appears on the equator.