el niño & la niña. three circulations of the oceans normal circulation (walker circulation) el...

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El Niño & La Niña

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Page 1: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

El Niño&

La Niña

Page 2: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

THREE CIRCULATIONS OF THE OCEANS

• Normal circulation (Walker circulation)

• El Nino circulation

• La Nina circulation

Page 3: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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)

Page 4: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

Normal Circulation

Page 5: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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

Page 6: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

El Nino Circulation

Page 7: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

Comparing two conditions• Normal condition

El Niño condition

Page 8: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

• 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

First signs of El Niño

Page 9: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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?

Page 10: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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

Page 11: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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

Page 12: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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

Page 13: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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

Page 14: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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

Page 15: El Niño & La Niña. THREE CIRCULATIONS OF THE OCEANS Normal circulation (Walker circulation) El Nino circulation La Nina circulation

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)