Scientists have identified a number of Kelvin waves at sea level moving across the ocean.
Madrid. (EP) -. Every ten days, the satellite Franco- Jason-2 checks all the world's oceans, monitoring changes in the height of the sea surface, a measure of heat in the upper layers of water.
Because our planet is water in more than 70% of its surface, this information is critical for global forecasts of weather and climate . Lately, Jason-2 has seen something ready in the Pacific and is very similar to what happened in 1997.
"It has made a model of heights and temperatures at the sea surface that reminds me of the way that the Pacific was seen in the spring of 1997," says Bill Patzert, climatologist at the Jet Propulsion Laboratory of NASA.
"That proved to be the precursor of a large El Niño". "I still can not say with certainty that a new El Niño will develop in 2014, or how big it can be, "says Mike McPhaden, NOAA," but Jason-2 data corroborated a report published last month.
" What Jason-2 has been seeing is a series of " Kelvin wave "massive waves in sea level moving across the Pacific, from Australia to South America. Forecasters are paying close attention because these waves could be a harbinger of El Niño.
The two phenomena, Kelvin waves and El Nino, are linked by the wind. Pacific trade winds blow from east to west, pushing surface water heated by the sun to Indonesia. As a result, sea level near Indonesia is usually higher than 45 which is about Ecuador inches.
Researchers call this area the "warm pool", which is the largest reservoir of warm water on our planet. Sometimes, however, the trade winds falter for a few days or weeks, and excess sea level creates a ripple to the Americas. "That's a Kelvin wave," said McPhaden. "It is rare to see a couple of them every winter."
Torrential rain in South America
El Niño -producing torrential rains in South America, around the Christmas holidays-occurs when the trade winds fell not just for a few days, but for many months. Then Kelvin waves cross the Pacific as a camper, raising sea levels and warmer equatorial waters leaving in its wake.
"El Niño of 1997-1998 was a textbook example" recalls Patzert. "Then we got the data from TOPEX / Poseidon, a predecessor Jason-2. Maps of sea surface showed a whitish lump, indicating a sea level about 10 inches taller than usual, moving Ecuador over from Australia to South America. "
"The same pattern was repeated in 2014," said McPhaden. "A series of Kelvin waves generated by explosions of wind located west in the western Pacific, started in mid January 2014 and headed east. This movement was enhanced by a third weakening of the trade winds of the Pacific occurred in mid-April. "
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