El Ni ñ o & La Ni ñ a

1. El Niño& La Niña

2. THREE CIRCULATIONS OF THE OCEANS • Normal circulation (Walker circulation) • El Nino circulation • La Nina circulation

3. Normal conditions (Walker conditions) • From Polar region, Peruvian current is circulating from eastern Pacific towards western Pacific. Strong trade winds are taking warm surface water towards west (ocean heats up to 28°C) while on the east upwelling occurs (raising of colder water what results with rich nutients for the fisheries) • Approaching to Australia and Indonesia, the air warms up due to high evaporation rate. This creates clouds and results with high precipitation (the proof > rainforests). • The overall result are floods around eastern coast of Australia and Indonesia while on the other side, the drught occur (Atacama desert)

4. Normal Circulation

5. El Niño circulation • Trade winds weaken and turn the direction • Blowing from western Pacific towards eastern Pacific, now the warm ocean surface water approaches coast of Peru where, after high evaporation, heavy rainfall occurs • This results with raise in sea level and couses floods >no upwelling > no rich nutrients > no fisheries • On eastern side of Australia, high pressure and dense clouds result with cold air • The consequences are drughts and fires in the rainforests

6. El Nino Circulation

7. Comparing two conditions • Normal condition El Niño condition

8. First signs of El Niño • Raise in air pressure over the Indian ocean, Indonesia and Australia • Fall in air pressure over Tahiti, central and eastern Pacific ocean • Weak trade winds heading east • Rising warm air in Peru causing rain in the deserts • Spreading of warm water from west Pacific and the Indian ocean to the east Pacific >> the cause is the rain in dry areas and drought in wet areas

9. Wider effects of El Niño condition • AFFECTING THE CLIMATE > storms, winds, floods and droughts • Affecting plants and animals • Economy > Fisheries > Diseases • Relation with hurricanes • Increasing bush fires and worsening haze • Decreasing air quality • Relation to Global Warming ? • Connections with La Nina?

10. History of El Niño • Occured in: > 1790-93 > 1828 > 1876-78 > 1891 > 1925-26 recently: > 1986-87 > 1991-92 > 1993, 1994, 1997-98, 2002-03, 2004-05, 2006-07

11. Case StudyEl Nino 1982. – 1983. -caused by broad expanse of water and heavy precipitation - raise in the surface of 11 feet • Consequences: • Around Peruvian coast >2000 deaths >losses of 13 billion $ • In Australia,Indonesia and Africa >droughts, dust storms and forest fires • In United States >sharks attack due to wet and warm spring

12. Case StudyEL Nino 1997. – 1998. -sea-surface temperature exceeding 28°C -rainfall in December 1997 and January 1998 reached 15 times the average - Consequences: Drought over Indonesia and Papua New Guinea >4.4 billion $ losses, famine and disease. Ecuador and Peru >floods and landslides,destruction of roads, houses and crops. Losses - 3.6 billion $, cholera and malaria Southern Africa >loss of 50% of the wheat crop, worth $US 130 million

13. La Nina circulation • La Nina is the opposite conditon of El Nino condition and the same but stronger Normal (Walker) condition • During La Nina, trade winds get stronger, blow in westernly direction, bring warm ocean surface water quicker while leaving even cooler water along the chilean coast • This results with floods along eastern Australia and very dry period along western side of South America causing fires

14. History of La Nina • Tends to follow El Nino effect with some exceptions • Some of the strong La Nina’s: > 1988 - 1989 > 1995 > 1999 – 2000 > 2000 – 2001 (minor exception, not expected) > 2007

15. The meaning of the names • El Nino (ENSO event – El Nino Southern Oscillation) • name given by South American Fishermans > spanish for “The Christ Child” (it came around Christmas time) • La Nina (anti-ENSO event) > spanish for “ The Child Girl” (analogous to El Nino)