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What is El Nino Southern Oscillation?
It is termed as opposite to the phenomenon of El Nino as it results in the ‘cooling’ of the ocean water in parts of the Pacific ocean. Both of them also result in changes in atmospheric conditions along with oceanic changes. Aspirants can read about La Nina in detail on the page link provided here. It is called El Nino Southern Oscillation.
What is El Nino and La Nina for the UPSC?
El Nino and La Nina or the ENSO is a very important concept in climatology in Geography for the UPSC exam. Since the phenomenon affects India and global weather conditions, it is to be studied in detail for the IAS exam. Adding to the topic’s importance is the impact it can have on Indian agriculture.
How long did the El Niño last in the 1990s?
In the 1990s, strong El Niños developed in 1991 and lasted until 1995, and from fall 1997 to spring 1998. In a normal year, a surface low pressure develops in the region of northern Australia and Indonesia and a high pressure system over the coast of Peru.
How do El Niño and La Niña affect the climate?
El Niño and La Niña have their strongest influence on global climate during the Northern Hemisphere winter. During La Niña winters, the southern tier of the United States is often drier than normal. Northern Australia, Indonesia, and the Philippines are often wetter than normal.
What happens during El Nino Southern Oscillation?
The El Niño Southern Oscillation (ENSO) is a periodic shift of the ocean-atmosphere system in the tropical Pacific that impacts weather around the world. It happens every 3-7 years (5 years on average) and typically lasts nine months to two years. It is associated with floods, droughts, and other global disturbances.
Is El Niño related to Southern Oscillation?
The Southern Oscillation is the atmospheric component of El Niño. This component is an oscillation in surface air pressure between the tropical eastern and the western Pacific Ocean waters. The strength of the Southern Oscillation is measured by the Southern Oscillation Index (SOI).
What is the El Nino Southern Oscillation Index?
The Southern Oscillation Index, or SOI, gives an indication of the development and intensity of El Niño or La Niña events in the Pacific Ocean. The SOI is calculated using the pressure differences between Tahiti and Darwin. Sustained negative values of the SOI below −7 often indicate El Niño episodes.
What do you mean by El Nino Southern Oscillation how it affects monsoon of India?
The El Nino weather phenomena is gaining strength. Later global forecasts indicate potentially affecting the south west from June to September monsoon of India. El Nino, characterized by warming of surface temperatures in the Pacific Ocean, is associated with lower than normal monsoon rainfall in India.
Why is El Niño called Southern Oscillation?
El Niño and the Southern Oscillation, also known as ENSO is a periodic fluctuation in sea surface temperature (El Niño) and the air pressure of the overlying atmosphere (Southern Oscillation) across the equatorial Pacific Ocean.
What is Southern Oscillation?
The Southern Oscillation is an index based on the pressure difference between two tropical South Pacific locations, and is closely related to the El Niño state.
What is El Niño Upsc?
El Nino refers to the large-scale ocean-atmosphere climate interaction linked to periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific. It is associated with high pressure in the western Pacific. El Nino adversely impacts the Indian monsoons and hence, agriculture in India.
What are the 3 stages of ENSO?
We can use surface-water temperatures in the eastern equatorial Pacific to designate conditions as one of three phases of the El Nino-Southern Oscillation (ENSO) system — neutral (or “normal”), warm (El Nino), and cold (La Nina).
How El Niño occurs?
An El Niño condition occurs when surface water in the equatorial Pacific becomes warmer than average and east winds blow weaker than normal. The opposite condition is called La Niña. During this phase of ENSO, the water is cooler than normal and the east winds are stronger. El Niños typically occur every 3 to 5 years.
How El Nino weakens Indian monsoon?
The warming in the tropical Pacific Ocean because of El Niño weakens the southeast trade winds flowing to the intertropical convergence zone over India. Since these winds are the main driving force of the Indian summer monsoon, El Niño events are associated with weak monsoons and lower than average rainfall.
How does Southern Oscillation El Nino & La Niña affect the Indian monsoon?
1. El Nino during winter causes warm conditions over the Indian subcontinent and during summer, it leads to dry conditions and deficient monsoon. Whereas La Nina results in better than normal monsoon in India.
What is El Nino explain any three features of it?
1 Answer. EL Nino means christian name called baby christ. (i) The presence of the EL-Nino leads to an increase in sea-surface temperatures. (ii) It weakens the trade winds in the regions and causes heavy rainfall, floods or droughts in different regions of the world.
El Nino
El Nino was first recognized by Peruvian fishermen off the coast of Peru as the appearance of unusually warm water. The Spanish immigrants called it El Nino, meaning “the little boy” in Spanish.
La Nina
La Nina means The Little Girl in Spanish. It is also sometimes called El Viejo, anti-El Nino, or simply "a cold event."
ENSO and India
El Nino: Strong El Nino events contribute to weaker monsoons and even droughts in India Southeast Asia.
El Nino
The phrase “ El Niño” refers to the Christ Child and was coined by fishermen along the coasts of Ecuador and Peru to describe the warming of the central and eastern pacific.
The El Niño Modoki
El Niño Modoki is a coupled ocean-atmosphere phenomenon in the tropical Pacific.
La Nina
After an El Niño event weather conditions usually return back to normal.
Madden-Julian Oscillation (MJO)
Madden – Julian oscillation (MJO) is the largest element of the intra-seasonal variability in the tropical atmosphere.
El Nino
El Niño is the name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru.
Indian Ocean Dipole effect (Not every El Nino year is same in India)
Although ENSO was statistically effective in explaining several past droughts in India, in the recent decades the ENSO-Monsoon relationship seemed to weaken in the Indian subcontinent. For e.g. the 1997, strong ENSO failed to cause drought in India.
The El Niño Modoki
El Niño Modoki is a coupled ocean-atmosphere phenomenon in the tropical Pacific.
La Nina
After an El Niño event weather conditions usually return back to normal.
El Nino – Effects on India
In a normal monsoon year (without El Nino), the pressure distribution is as follows:
Measuring El Nino
Scientists, governments, and non-governmental organizations (NGOs) collect data about El Nino using a number of technologies such as scientific buoys.
How did El Nino get its name?
The phenomenon became known as El Niño because of its tendency to occur around Christmas time. El Niño is Spanish for “the boy child” and is named after the baby Jesus.
What are the negative effects of El Nino?
Severe drought and associated food insecurity, flooding, rains, and temperature rises due to El Niño are causing a wide range of health problems, including disease outbreaks, malnutrition, heat stress and respiratory diseases.
El Nino
The phrase “El Niño” refers to the Christ Child and was coined by fishermen along the coasts of Ecuador and Peru to describe the warming of the central and eastern pacific.
During an El Nino event
The wind-forced upwelling that draws cool water to the surface slows down, and the warm water that has pooled up in the western part of the Pacific basin starts to slosh back toward the east.
El Nino Southern Oscillation (ENSO)
It is called El Nino Southern Oscillation. In normal times, when the tropical south Pacific ocean experiences high pressure, alternatively the tropical Indian ocean experiences low pressure conditions.
Mitigation Of Effects
Scientists, governments, and non-governmental organizations (NGOs) collect data about El Nino using a number of technologies such as scientific buoys.
Impact of La Nina
Europe: In Europe, El Nino reduces the number of autumnal hurricanes. La Nina tends to lead to milder winters in Northern Europe (especially UK) and colder winters in southern/western Europe leading to snow in the Mediterranean region.
El Nino
El Nino means ‘little boy’ or ‘Christ child’ in Spanish. The phenomenon was thus named because it was first recognised by South American fishermen in the early part of the 17th century. The events, i.e., warm waters in the Pacific Ocean, tended to occur in December, hence, the name was chosen.
La Nina
La Nina means ‘little girl’ in Spanish and is also known as El Viejo or ‘cold event’. Here, the water temperature in the Eastern Pacific gets colder than normal. As a result of this, there is a strong high pressure over the eastern equatorial Pacific. Now, there is low pressure in the Western Pacific and off Asia.
El Nino and La Nina Effects on India
Since 1950, out of the 13 droughts that India faced, 10 have been during El Nino years and one in a La Nina year. This is because in general, an El Nino means lesser than average rains for India.
Frequently Asked Questions about El Nino and La Nina
Severe drought and associated food insecurity, flooding, rains, and temperature rises due to El Niño are causing a wide range of health problems, including disease outbreaks, malnutrition, heat stress and respiratory diseases.