EL NIŇO - SOUTHERN
OSCILLATION
(ENSO)
Kamila Klemešová
Geography
12.12.2009
ENSO = El Niňo (EN) + Southern
Oscillation (SO)
 ENSO - a global event arising from large-scale
interaction between the ocean and the atmoshere
 El Niňo – an extensive ocean warming that begins along
the coast of Peru and Ecuador.
 Southern Oscillation – the reversal of surface air
pressure at opposite ends of the tropical Pacific Ocean
that occur during major El Niňo events.
 La Niňa – A condition where the central and eastern
tropical Pacific Ocean turns cooler than normal.
Ocean currents
www.freewebs.com/svobelisk/Route_Map/ocean_currents2_resized.jpg
Global circulation
 Trade winds
occupy most
of the tropics
and blow from
the subtropical
hights to the
equatorial low.
www.inthewakeofthebelgica.com
Characteristic of El Niňo
 Weakening of the trade
winds and warming of
the surface layers in
the eastern and central
equatorial Pacific
Ocean
 Events occur irregularly
at intervals of 2-7
years.
 Water temperature
near Peru rises =>
death of marine plants,
fishs etc…
www.ccc-weather.com
Sea surface height
 is a measure of heat
stored in the upper
ocean.
 Red and white colour
- higher and warmer
water
 Purple colour – lower
and cooler water
http://science.nasa.gov
Atmospheric and ocean circulation
www.chmi.cz
www.chmi.cz
Atmospheric and ocean circulation
during El Niňo
www.chmi.cz
www.chmi.cz
El Niňo – red, La Niňa - blue www.john-daly.com
SOI
 normalized difference in surface pressure between
Tahiti, French Polynesia and Darwin, Australia.
 We measure the strength of the trade winds, which have
a component of flow from regions of high to low pressure
 High SOI – big pressure difference
La Niňa conditions – trade
winds are stronger than normal
 Low SOI – small pressure difference => El Niňo
conditions – trade winds are weaken than
normal
Interests of El Niňo
 El Niño typically lasts 9-12 months.
 La Niña typically lasts 1-3 years.
 El Niňo events occur once every 2 to 7
years.
 El Niño means The Little Boy or Christ
child in Spanish. This name was used for
the tendency of the phenomenon to arrive
around Christmas.
 La Niña means The Little Girl.
Impacts of El Niňo
Changes in the Pacific ocean
 Warmer ocean near Peru cause the
decrease of chlorophyll => fishs, marine
plants die => less oxygen in the ocean…
e.g. produce of Peruvian anchovy :
1971 – 10,3 million metric ton
1972 – 4,6 million metric ton (El Niňo)
Changes in the produce of
chlorophyll in the Pacific ocean
Global impact of El Niňo
Fires in Australia
(Victoria)
10th January 1997
11th January 1997
Economic impacts
www.pmel.noaa.gov
 El Niňo 1982-1983
damage worth more
than 8 billion
 El Niňo 1997-1998
 El Nino was
estimated to be on
the order of $25
billion.
El Niňo 1982 - 1983
1. Drought and bush fires
2. Crops fail, starvation follows
3. Drought,fresh water
shortages
4. Tahiti-6 tropical cyclones
5. Fish industry devastated
6. Across the Pacific-Coral
reefs die
7. Colorado River basinflooding,
mud slides
8. Gulf states-Downpours
cause death, property
damage
9. Peru, Ecuador-Floods,
landslides
10. Southern Africa-Drought,
disease, malnutrition
 Manyara National
Park – trees
destroyed by floods
during El Niňo 1997
Floods in Peru, 1997
skywatch-media.com
www.yeungstuff.com
Floods in California 1997
Sources
 NASA (National Aeronautics and Space
Administration)
 NOAA (National Oceanic and Atmospheric
Administration), http://www.nws.noaa.gov/
 CHMU ( Czech Hydromoteorological
Institute), www.chmi.cz
 Ahrens, C.D., Meteorology today,
Brooks/Cole, 544 p., ISBN 0-534-39771-9