El Niño refers to the irregular warming in
the sea surface temperatures from the coasts of Peru and Ecuador
to the equatorial central Pacific. This causes a disruption of
the ocean-atmosphere system in the tropical Pacific having important
consequences for weather around the globe. This phenomenon is not
totally predictable but on average occurs once every four years.
It usually lasts for about 18 months after it begins.
During the 1997-98 El Niño, sea surface temperatures
in the central and eastern equatorial Pacific were higher than normal.
The sea surface temperature for September 1997 was the highest in
the last 50 years. Also, in late September easterly winds over the
equatorial Pacific between 150E and 120W decreased the most in the
last 30 years.
Recent years in which El Niño events have occurred
are 1951, 1953, 1957-1958, 1965, 1969, 1972-1973, 1976, 1982-1983,
1986-1987, 1991-1992, 1994 and 1997. The high sea surface temperatures
and the magnitude of the westerly wind anomalies over the Pacific
are very high. These conditions suggest that the strength of 1997
El Niño event could equal or surpass that in 1982-1983, making it
the strongest El Niño this century.
The El Niño of 1982-83 was responsible for
the loss of nearly 2,000 lives and displacement of hundreds of thousands
from their homes. The losses were caused by droughts and fires in
Australia, Southern Africa, Central America, Indonesia, the Philippines,
South America and India. There were floods in the USA, Gulf of Mexico,
Peru, Ecuador, Bolivia and Cuba. More hurricanes than usual affected
Hawaii and Tahiti.
What's in this section?
- Explain what El Niño is, where it is located, and how it is
- Describe the weather changes caused by El Niño.
- Draw the patterns of El Niño on a world map.
- List the years of previous El Niño events.
- Locate and graph precipitation for locations in the eastern
and western Pacific.
- Analyze precipitation in eastern and western Pacific in terms
of amount and when it occurred.
- Compare precipitation amounts in the eastern and western Pacific
to occurrences of El Niño.
- Predict the economic effects El Niño will have on the areas
- Predict when the next El Niño will develop.
- Predict what would happen to coastal areas of the Atlantic Ocean
if El Niño developed off the coast of Africa.
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