Chronology of Events in the History of Understanding El Niño and La Niña

late 1800s
Fishermen coin the name El Niño to refer to the periodic warm waters that appear off the coasts of Peru and Ecuador around Christmas.

1928
Gilbert Walker describes the Southern Oscillation, the seesaw pattern of atmospheric pressure readings on the eastern and western sides of the Pacific Ocean.

1957
Large El Niño occurs and is tracked by scientists participating in the International Geophysical Year. Results reveal that El Niño affects not just the coasts of Peru and Ecuador but the entire Pacific Ocean.

1969
Jacob Bjerknes, of the University of California, Los Angeles, publishes a seminal paper that links the Southern Oscillation to El Niño.

1975
Klaus Wyrtki, of the University of Hawaii, tracks sea levels across the Pacific and establishes that an eastward flow of warm surface waters from the western Pacific causes sea surface temperatures to rise in the eastern Pacific.

1976
Researchers use an idealized computer model of the ocean to demonstrate that winds over the far western equatorial Pacific can cause sea surface temperature changes off Peru.

1982
A severe El Niño develops in an unexpected manner, but its evolution is recorded in detail with newly developed ocean buoys.

1985
Several nations launch the Tropical Ocean-Global Atmosphere (TOGA) program, a 10-year study of tropical oceans and the global atmosphere.

1986
Researchers design the first coupled model of ocean and atmosphere that accurately predicts an El Niño event in 1986.

1988
Researchers explain how the "memory" of the ocean--the lag between a change in the winds and the response of the ocean--influences terminations of El Niño and the onset of La Niña.

1996-1997
The array of instruments monitoring the Pacific, plus coupled ocean-atmosphere models, enable scientists to warn the public of an impending El Niño event.

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