(EL NINO-SOUTHERN OSCILLATION)
CONSEQUENCES OF EL NINO
When this phenomenon occurs, many countries
Waters are less warm in Indonesia and anticyclones
are created instead of the depressions. Which causes droughts
in Australia and Indonesia, see also forest fires in areas
that usually have abundant rainfall. But there are fewer hurricanes
in the Western Pacific.
These waters which are brought across the
Pacific cause a decrease of atmospheric pressure so an increase
of precipitation on
the East coast of South America (especially northern Brazil,
the Peru) : see major flooding
in usually desert areas.
In December 1997 and January 1998 during
the "El Niño",
the Equator and North of the Peru received from 350
to 775 mm of rain and is 15 times more than normal.
Hurricanes affecting Polynesia are on the
increase well as number tornadoes,
causing dramatic consequences. The water it warms up it intersects
of cold water and nutrient-rich foods, and many kinds of fishes
migrate towards the Pole, severely reducing the population
in this part of the Pacific Ocean.
South and East Africa, South India, and Pakistan
are also experiencing droughts
and the floods
in India are sporadic.
In the Atlantic ocean the number of hurricanes
decreased during the El Niño phenomenon.
here to see the (SST) sea surface temperature anomalies
and the sea surface height (SSH) above animated.
El Niño from December to
El Niño from June to August
||Cool and rainy
||Warm and rainy
||Warm and dry
||Cool and dry
here to see an animation of the evolution of the snow cover
August to July during El Niño years (1982/83, 1986/87
Red tones indicate less snow cover, blue tones indicate more
During El Niño events, jet streams
are intensifying because the rise in the
central Pacific temperature increases the pressure difference
between the equator
and mid-latitudes. Then the jet
streams determine the path of the mid-latitude storms.
here to see the effect of El Nino on the Jet Stream
As you can see, during the years of
in yellow) the
surface temperature of the water in the East Pacific along
the equator is
higher than normal. The atmospheric pressure at Darwin and
the records of
rainfall at Christmas Islands in the central Pacific are also
higher than normal.
here to see the simulation of rainfall anomalies caused by
observed from 1982 to 1998.
here for the forecast of El Niño or La Niña
Since 2007 a new type of El Niño was
found from the analysis of a Japanese group who named it warm
pool El Niño or El Nino Modoki in Japanese. This El
Niño is distinguished from its cousin by its specific
impact on global atmospheric circulation..
Traditionally, the classic El Niño
is associated with warming in the East tropical Pacific (Niño
1+2 et 3). However, during the El Niño Modoki sea
surface temperature (SST) anomaly in East Pacific is not affected
by a warming but rather by cooling just like the western equatorial
Pacific, while a warm anomaly affects the central equatorial
3.4). These zonal gradients of SST translat into anomaly
of two cells of the Walker Circulation on the tropical Pacific,
with a humid region in the central Pacific. The thermocline
doesn't tilt in the same way because during El Niño
classic it rise up in West equatorial Pacific for descend
in Eastern Pacific while during his cousin the thermocline
rises at each end of the equatorial Pacific Ocean and sinks
in the center of the Pacific.
Comparison during the situation of classic El Niño
(a) and El Niño Modoki (b)
During classic El Niño West Coast
of the United States is humid but during El Niño Modoki
is rather dry. While during the classic El Niño there
is a significant reduction of precipitation over the north
and south of Australia, but Modoki event appears to result
in a large-scale reduction in rainfall in the North West and
Northern Australia. India is also affected by droughts with
this second type of El Niño unlike classic phenomenon
has long been known.
Régnier helped me correct mistakes, please you to visit
Im not english speaker, some improprieties can appear
to english masters.
Could you help me reporting by mail any fault you read. Thank
you for all.