What is El Niño?
El Niño,
the arrival of unusually warm water in the Pacific, was originally recognized
and named by fishermen off the coast of
During the non-El Niño years, the trade winds blow west across the
tropical pacific – piling up warm surface water in the western Pacific. This
results in a steep thermocline and the sea surface being about half a meter
higher in the west than in the east. Upwelling
occurs along the South American coast, bringing up cold water from the bottom.
Non-El Niño
Condition: There is a pileup of warm surface water in the western Pacific. The
thermocline is also rather steep.
( Source: http://www.pmel.noaa.gov/tao/elnino/nino-home.html
)
In contrast, during an El Niño year, the trade winds weaken or even
reverse! This causes the warm surface water to flow from the east to the west –
flattening out the sea surface and the thermocline. The ultimate result is warm
water off the coast of tropical
El Niño Condition: The warm surface water has moved
from the west to the east. The thermocline is also flattened out.
( Source: http://www.pmel.noaa.gov/tao/elnino/nino-home.html
)
An informative animation of the El Niño event can be found here.
