El Niño / Southern Oscillation (ENSO)
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El El NiñoNiño / Southern / Southern OscillationOscillation(ENSO)(ENSO)
By Sagar BoraBy Sagar Bora
University of BremenUniversity of Bremen
04/19/23 2Presented by Sagar Bora
OutlineOutline
Motivation/HistoryMotivation/History El – NiEl – Niñño/La Nio/La Niñña definitiona definition Normal Conditions in the Pacific OceanNormal Conditions in the Pacific Ocean El – NiEl – Niñño Conditionso Conditions La-NiLa-Niñña Conditionsa Conditions Effects of El – NiEffects of El – Niñño and La-Nio and La-Niññaa El – NiEl – Niñño factso facts SummarySummary
04/19/23 3Presented by Sagar Bora
El Niño El Niño
From the mid 18th century, Peruvian fisherman noticed that their harvest completely failed every few years.
This periodic event was associated with unusually warm waters off the coast of Peru.
Since the periodic warming almost always occurred around December, the fisherman named it El Niño, in reference to the Christ child.
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 4Presented by Sagar Bora
Southern OscillationSouthern Oscillation
In the late 19th century Gilbert Walker, the head of the Indian Meteorological Service notices that the Indian monsoon fails periodically every few years, leading to drought and famine in India.
Search for a way to predict the Indian monsoon.
Identified a peculiar see-saw relationship between pressure over the maritime continent and India and the Pacific near South America.
He called this relationship the Southern Oscillation.
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 5Presented by Sagar Bora
ENSOENSO
In 1969, UCLA professor Jacob Bjerknes was the first to recognize that El Niño and the Southern Oscillation are actually manifestations of the same physical phenomenon and that it results from an unstable interaction between the atmosphere and the ocean. This resulted in the term ENSO to refer to this phenomenon.
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 6Presented by Sagar Bora
Why should we study El Niño?Why should we study El Niño?
Reduced upwelling off the coast of South Reduced upwelling off the coast of South America. So periodic failure of fishery America. So periodic failure of fishery near Peru, which normally is responsible near Peru, which normally is responsible for one-fifth of global fish production. for one-fifth of global fish production. High coral mortalityHigh coral mortality
Drought in South-east Asia, India, Drought in South-east Asia, India, Australia and AfricaAustralia and Africa
Heavy rainfall in the South AmericasHeavy rainfall in the South Americas
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 7Presented by Sagar Bora
El – Niño definitionEl – Niño definition
From: www.weathersa.co.za El NiñoNiño : When the When the three-month running mean three-month running mean of of
the the Sea Surface Temperature Sea Surface Temperature anomalies in the anomalies in the Nino 3.4 region are greater than or equal to 0.5°C, Nino 3.4 region are greater than or equal to 0.5°C, an El Niño event is assumed to be taking place. an El Niño event is assumed to be taking place.
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 8Presented by Sagar Bora
La Niña definitionLa Niña definition
From: www.weathersa.co.za La NiñaNiña : When the When the three-month running mean three-month running mean
of the of the Sea Surface Temperature Sea Surface Temperature anomalies in anomalies in the Nino 3.4 region are greater than or equal the Nino 3.4 region are greater than or equal to -0.5°C, an La Nina event is assumed to be to -0.5°C, an La Nina event is assumed to be taking place. taking place.
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 9Presented by Sagar Bora
Normal Conditions in the Normal Conditions in the Pacific OceanPacific Ocean
Nutrient rich cool water Nutrient rich cool water along the Peruvian along the Peruvian coast (eastern pacific) coast (eastern pacific) due to upwelling;due to upwelling;
good for marine life;good for marine life; Shallow mixed layer; Shallow mixed layer;
thermocline raisedthermocline raised 3 to 8 °C warmer water 3 to 8 °C warmer water
in the west Pacific near in the west Pacific near Australia, IndonesiaAustralia, Indonesia
Deep mixed layer; Deep mixed layer; thermocline pushed thermocline pushed down down
From: www.weathersa.co.za
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 10Presented by Sagar Bora
Normal Conditions in the Normal Conditions in the Pacific OceanPacific Ocean
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz
04/19/23 11Presented by Sagar Bora
Normal Conditions in the Normal Conditions in the atmosphereatmosphere
High pressure in the east above High pressure in the east above the cold water, low pressure in the cold water, low pressure in the west above the warmer the west above the warmer waterwater
Pressure gradients result in Pressure gradients result in easterly trade winds which in easterly trade winds which in turn results in upwelling along turn results in upwelling along the Peruvian coastthe Peruvian coast
Trade winds brings moist warm Trade winds brings moist warm air towards Indonesian region air towards Indonesian region which rises and travels eastward which rises and travels eastward before sinking in the east. This before sinking in the east. This is a thermally direct circulation is a thermally direct circulation found by Sir G. Walker. found by Sir G. Walker.
From: www.weathersa.co.za
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 12Presented by Sagar Bora
El – Niño Conditions in the El – Niño Conditions in the atmosphere atmosphere
Easterly winds weakens, even Easterly winds weakens, even changes directions sometimes changes directions sometimes and becomes westerlies due to and becomes westerlies due to change in the sign of pressure change in the sign of pressure gradient. Sir Walker called gradient. Sir Walker called this east-west seesaw in this east-west seesaw in
southern Pacific pressuresouthern Pacific pressure ““Southern OscillationSouthern Oscillation””
From: www.weathersa.co.za
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 13Presented by Sagar Bora
El Niño conditions in the El Niño conditions in the Pacific OceanPacific Ocean
Due to change in the wind Due to change in the wind direction, the currents on the direction, the currents on the ocean also slows down or ocean also slows down or changes direction from changes direction from westward to eastward. westward to eastward.
SST rises in the eastern SST rises in the eastern pacific and the western pacific and the western pacific cools down a bit; pacific cools down a bit; Downwelling occurs off the Downwelling occurs off the coast of Peru; nutrient-less coast of Peru; nutrient-less warm surface water leads to warm surface water leads to decline in marine lifedecline in marine life
Rainy conditions move with Rainy conditions move with the warmer SST and dry the warmer SST and dry conditions move with the conditions move with the coldcoldFrom:
www.weathersa.co.za
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 14Presented by Sagar Bora
El Niño Conditions in the El Niño Conditions in the Pacific OceanPacific Ocean
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz
04/19/23 15Presented by Sagar Bora
A normal year and an El Niño A normal year and an El Niño yearyear
Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 16Presented by Sagar Bora
La Niña conditionsLa Niña conditions During La Niña years, the During La Niña years, the
upwelling off the Peruvian upwelling off the Peruvian coast is enhanced and the coast is enhanced and the SSTs in the SSTs in the Nino regions Nino regions become cooler than usual. become cooler than usual.
The Walker Circulation The Walker Circulation operates in the same way as operates in the same way as described for normal years, described for normal years, but because of the larger but because of the larger area of colder water off the area of colder water off the South American coast and South American coast and the displacement of warmer the displacement of warmer water to the west, the water to the west, the atmospheric pattern also atmospheric pattern also shifts accordingly. Heavier shifts accordingly. Heavier rainfall over Australia and rainfall over Australia and Indonesia and dry spans over Indonesia and dry spans over South AmericasSouth Americas
From: http://www.wrh.noaa.gov/
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
04/19/23 17Presented by Sagar Bora
La Niña conditions in the La Niña conditions in the Pacific OceanPacific Ocean
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz
04/19/23 18Presented by Sagar Bora
Global impacts of El Niño Global impacts of El Niño
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz
04/19/23 19Presented by Sagar Bora
Global impacts of La NiñaGlobal impacts of La Niña
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
EffectEffectss
FactsFacts SummarSummaryy
Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz
04/19/23 20Presented by Sagar Bora
El Niño factsEl Niño facts
ENSO is not a weather anomaly, it’s a part ENSO is not a weather anomaly, it’s a part of a cycle. of a cycle.
Every weather anomaly throughout the Every weather anomaly throughout the world that occurs during an El Niño year is world that occurs during an El Niño year is not caused by that El Niño.not caused by that El Niño.
The impact of global warming on El Niño is not as yet known, speculation notwithstanding.
Forecasting El Niño’s onset does not tell us much about its other characteristics (e.g., intensity, frequency, duration).
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
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FactsFacts SummarSummaryy
04/19/23 21Presented by Sagar Bora
Summary and conclusionsSummary and conclusions
El NiñoEl Niño , La Nina and the Southern Oscillations are coupled , La Nina and the Southern Oscillations are coupled phenomenon that occurs periodically at the Pacific Ocean. phenomenon that occurs periodically at the Pacific Ocean.
Normally, SST and SSH at the eastern pacific is lower than Normally, SST and SSH at the eastern pacific is lower than the western pacific. the western pacific.
During El NiñoDuring El Niño , it’s the opposite of the normal conditions. , it’s the opposite of the normal conditions. SST and SSH rises in the eastern pacific and easterlies SST and SSH rises in the eastern pacific and easterlies slows down or changes direction.slows down or changes direction.
La Niña is the extreme of the normal conditions. SST at the La Niña is the extreme of the normal conditions. SST at the east coast decreases more than usual. east coast decreases more than usual.
Both La NiñaBoth La Niña and El Niñoand El Niño effects the global climate and the effects the global climate and the economy of many countries. economy of many countries.
MotivatioMotivationn
DefinitionsDefinitions Normal Normal conditionsconditions
El NinoEl Nino La La NinaNina
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FactsFacts SummarSummaryy
04/19/23 22Presented by Sagar Bora
Thank you for Listening!!Thank you for Listening!!Questions?Questions?
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