El Nino

<<–2/”>a >p style=”font-weight: 400;”>El Nino

El Niño is the name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru.
When this warming occurs the usual upwelling of cold, nutrient rich deep ocean water is significantly reduced.
El Niño normally occurs around Christmas and usually lasts for a few weeks to a few months.
Sometimes an extremely warm event can develop that lasts for much longer time periods. In the 1990s, strong El Niños developed in 1991 and lasted until 1995, and from fall 1997 to spring 1998.

Normal Conditions

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. As a result, the trade winds over the Pacific Ocean move strongly from east to west.
The easterly flow of the trade winds carries warm surface waters westward, bringing convective storms (thunderstorms) to Indonesia and coastal Australia. Along the coast of Peru, cold bottom cold nutrient rich water wells up to the surface to replace the warm water that is pulled to the west.

Walker circulation (Occurs during Normal Years)

The Walker circulation (walker cell) is caused by the pressure gradient force that results from a high pressure system over the eastern Pacific ocean, and a low pressure system over Indonesia.

This cross-section of the Pacific Ocean, along the equator, illustrates the pattern of atmospheric circulation typically found at the equatorial Pacific. Note the position of the thermocline.

Thermocline == Noun a temperature gradient in a lake or other body of water, separating layers at different temperatures.
The Walker cell is indirectly related to upwelling off the coasts of Peru and Ecuador. This brings nutrient-rich cold water to the surface, increasing fishing stocks.

During El Nino year

In an El Niño year, air pressure drops over large areas of the central Pacific and along the coast of South America.
The normal low pressure system is replaced by a weak high in the western Pacific (the southern oscillation). This change in pressure pattern causes the trade winds to be reduced == Weak Walker Cell. Sometimes Walker Cell might even get reversed.

This reduction allows the equatorial counter current (current along doldrums) to accumulate warm ocean water along the coastlines of Peru and Ecuador.
This accumulation of warm water causes the thermocline to drop in the eastern part of Pacific Ocean which cuts off the upwelling of cold deep ocean water along the coast of Peru.
Climatically, the development of an El Niño brings drought to the western Pacific, rains to the equatorial coast of South America, and convective storms and hurricanes to the central Pacific.

This cross-section of the Pacific Ocean, along the equator, illustrates the pattern of atmospheric circulation that causes the formation of the El Niño.

In the image above, we can see the presence of a strong El Niño event (October, 1997).

Effects of El Nino

The warmer waters had a devastating effect on marine life existing off the coast of Peru and Ecuador.
Fish catches off the coast of South America were lower than in the normal year (Because there is no upwelling).
Severe droughts occur in Australia, Indonesia, India and southern Africa.
Heavy rains in California, Ecuador, and the Gulf of Mexico.

Normal Conditions

Eastern Pacific == Coast of Peru and Ecuador == Cold Ocean Water == Good for Fishing.

Western Pacific == Indonesia and Australia == Warm Ocean Water == Plenty of rains.

El Nino Condition

Eastern Pacific == Coast of Peru and Ecuador == Warm Ocean Water == Fishing Industry takes a hit.

Western Pacific == Indonesia and Australia == Cold Ocean Water == Drought.

How El Nino impacts monsoon rainfall in India

El Nino and Indian monsoon are inversely related.
The most prominent droughts in India – six of them – since 1871 have been El Nino droughts, including the recent ones in 2002 and 2009
However, not all El Nino years led to a drought in India. For instance, 1997/98 was a strong El Nino year but there was no drought (Because of IOD).
On the other hand, a moderate El Nino in 2002 resulted in one of the worst droughts.
El Nino directly impacts India’s agrarian economy as it tends to lower the production of summer crops such as rice, sugarcane, Cotton and oilseeds.
The ultimate impact is seen in the form of high Inflation and low gross domestic product Growth as agriculture contributes around 14 per cent to the Indian economy.

El Nino Southern Oscillation [ENSO]

The formation of an El Niño [Circulation of Water] is linked with Pacific Ocean circulation pattern known as the southern oscillation [circulation of Atmospheric Pressure]
Southern Oscillation, in Oceanography and Climatology, is a coherent inter-annual fluctuation of atmospheric pressure over the tropical Indo-Pacific region.
El Nino and Southern Oscillation coincide most of the times hence their combination is called ENSO – El Nino Southern Oscillation.

Only El Nino == [Warm water in Eastern Pacific + Cold water in Western Pacific].

Only SO == [Low Pressure over Eastern Pacific + High Pressure over Western Pacific]

ENSO = [Warm water in Eastern Pacific + Low Pressure over Eastern Pacific] + [Cold water in Western Pacific + High Pressure over Western Pacific].

Southern Oscillation Index and Indian Monsoons

SO is a see-saw pattern of meteorological changes observed between the Eastern Pacific and Western Pacific.
When the pressure was high over equatorial Eastern Pacific, it was low over the equatorial Western Pacific and vice versa.
The pattern of low and high pressures gives rise to vertical circulation along the equator with its rising limb over low pressure area and descending limb over high pressure area. This is known as Walker Circulation.
The location of low pressure and hence the rising limb over Western Pacific is considered to be conductive to good monsoon rainfall in India.
Its shifting eastward from its normal position, such as in El Nino years, reduces monsoon rainfall in India.
Due to the close association between an El Nino (E.N.) and the Southern Oscillation SO the two are jointly referred to as an ENSO event.
The periodicity of SO is not fixed and its period varies from two to five years.
Southern Oscillation Index (SOD) is used to measure the intensity of the Southern Oscillation.
This is the difference in pressure between Tahiti in French Polynesia (Central Pacific), representing the Central Pacific Ocean and Port Darwin, in northern Australia representing the Eastern Pacific Ocean.
The positive and negative values of the SOI i.e. Tahiti minus the Port Darwin pressure are pointers towards good or bad rainfall in India.

Positive SOI	Negative SOI
Tahiti pressure greater than that of Port Darwin	Reverse
Pressure high over eastern Pacific and low over	Reverse
Drought conditions in Eastern Pacific and good rainfall in Western Pacific (Northern Australia and Indonesia)	Reverse
Good for Indian Monsoons	Bad for Indian Monsoons

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.
However, it was later discovered that just like ENSO was an event in the Pacific Ocean, a similar seesaw ocean-Atmosphere system in the Indian Ocean was also at play. It was discovered in 1999 and named the Indian Ocean Dipole (IOD).
The Indian Ocean Dipole (IOD) is defined by the difference in sea surface temperature between two areas (or poles, hence a dipole) – a western pole in the Arabian Sea (western Indian Ocean) and an eastern pole in the eastern Indian Ocean south of Indonesia.
IOD develops in the equatorial region of Indian Ocean from April to May peaking in October.
With a positive IOD winds over the Indian Ocean blow from east to west (from Bay of Bengal towards Arabian Sea). This results in the Arabian Sea (western Indian Ocean near African Coast) being much warmer and eastern Indian Ocean around Indonesia becoming colder and dry.
In the negative dipole year (negative IOD), reverse happens making Indonesia much warmer and rainier.
It was demonstrated that a positive IOD index often negated the effect of ENSO, resulting in increased Monsoon rains in several ENSO years like the 1983, 1994 and 1997.
Further, it was shown that the two poles of the IOD – the eastern pole (around Indonesia) and the western pole (off the African coast) were independently and cumulatively affecting the quantity of rains for the Monsoon in the Indian subcontinent.
Similar to ENSO, the atmospheric component of the IOD was later discovered and named as Equatorial Indian Ocean Oscillation [EQUINOO][Oscillation of warm water and atmospheric pressure between Bay of Bengal and Arabian Sea].

Impact on IOD on Cyclonogeneis in Northern Indian Ocean

Positive IOD (Arabian Sea warmer than Bay of Bengal) results in more Cyclones-2/”>Cyclones than usual in Arabian Sea.
Negative IOD results in stronger than usual cyclonogenesis (Formation of Tropical Cyclones) in Bay of Bengal. Cyclonogenesis in Arabian Sea is suppressed.

The El Niño Modoki

El Niño Modoki is a coupled ocean-atmosphere phenomenon in the tropical Pacific.
It is different from another coupled phenomenon in the tropical Pacific namely, El Niño.
Conventional El Niño is characterized by strong anomalous warming in the eastern equatorial Pacific.
Whereas, El Niño Modoki is associated with strong anomalous warming in the central tropical Pacific and cooling in the eastern and western tropical Pacific (see figure below).

El Niño Modoki Impacts

The El Niño Modoki phenomenon is characterized by the anomalously warm central equatorial Pacific flanked by anomalously cool regions in both west and east.
Such zonal gradients result in anomalous two-cell Walker Circulation over the tropical Pacific, with a wet region in the central Pacific.

El NiÃ±oâSouthern Oscillation (ENSO) is a Climate pattern that occurs across the tropical Pacific Ocean every few years. ENSO is characterized by changes in sea surface temperature, atmospheric pressure, and winds. El NiÃ±o and La NiÃ±a are the two phases of ENSO. El NiÃ±o is characterized by warmer-than-Average sea surface temperatures in the eastern tropical Pacific Ocean, while La NiÃ±a is characterized by cooler-than-average sea surface temperatures in the same region.

ENSO can have a significant impact on weather patterns around the world. El NiÃ±o events are often associated with drier-than-average conditions in the southern United States and wetter-than-average conditions in the northern United States. La NiÃ±a events are often associated with wetter-than-average conditions in the southern United States and drier-than-average conditions in the northern United States.

ENSO is a natural climate pattern, but human activities are believed to be making ENSO events more intense and more frequent. Climate Change is causing the Earth’s atmosphere to warm, which is leading to more extreme weather events, including El NiÃ±o and La NiÃ±a events.

Scientists are working to better understand ENSO and its impacts. They are also working to develop ways to predict ENSO events so that people can prepare for their impacts.

El NiÃ±o

El NiÃ±o is a climate pattern that occurs across the tropical Pacific Ocean every few years. El NiÃ±o is characterized by warmer-than-average sea surface temperatures in the eastern tropical Pacific Ocean. El NiÃ±o events can last for several months or even years.

El NiÃ±o events can have a significant impact on weather patterns around the world. El NiÃ±o events are often associated with drier-than-average conditions in the southern United States and wetter-than-average conditions in the northern United States. El NiÃ±o events can also lead to changes in sea level, Precipitation, and temperature.

La NiÃ±a

La NiÃ±a is a climate pattern that occurs across the tropical Pacific Ocean every few years. La NiÃ±a is characterized by cooler-than-average sea surface temperatures in the eastern tropical Pacific Ocean. La NiÃ±a events can last for several months or even years.

La NiÃ±a events can have a significant impact on weather patterns around the world. La NiÃ±a events are often associated with wetter-than-average conditions in the southern United States and drier-than-average conditions in the northern United States. La NiÃ±a events can also lead to changes in sea level, precipitation, and temperature.

ENSO and Climate Change

ENSO is a natural climate pattern, but human activities are believed to be making ENSO events more intense and more frequent. Climate change is causing the Earth’s atmosphere to warm, which is leading to more extreme weather events, including El NiÃ±o and La NiÃ±a events.

Scientists are working to better understand how climate change is affecting ENSO. They are also working to develop ways to predict ENSO events so that people can prepare for their impacts.

ENSO Monitoring

ENSO is monitored by a number of different organizations, including the National Oceanic and Atmospheric Administration (NOAA) and the International Research Institute for Climate and Society (IRI). These organizations use a variety of data, including sea surface temperature, atmospheric pressure, and wind data, to track ENSO events.

ENSO Research

A great deal of research is being conducted on ENSO. Scientists are working to better understand how ENSO works, how it is affected by climate change, and how it can be predicted. This research is important for developing strategies to mitigate the impacts of ENSO.

ENSO Terminology

There are a number of terms that are used to describe ENSO. Some of these terms include:

El NiÃ±o: A climate pattern that is characterized by warmer-than-average sea surface temperatures in the eastern tropical Pacific Ocean.
La NiÃ±a: A climate pattern that is characterized by cooler-than-average sea surface temperatures in the eastern tropical Pacific Ocean.
ENSO: A climate pattern that occurs across the tropical Pacific Ocean every few years. ENSO is characterized by changes in sea surface temperature, atmospheric pressure, and winds.
ENSO event: A period of time when ENSO is in one of its two phases, El NiÃ±o or La NiÃ±a.
ENSO cycle: The complete cycle of ENSO, from one El NiÃ±o event to the next.
ENSO prediction: The process of predicting when an ENSO event will occur and how strong it will be.
ENSO monitoring: The process of tracking ENSO events and their impacts.
ENSO research: The process of studying ENSO in order to better understand how it works and how it can be predicted.

What is climate change?

Climate change is the long-term shifts in temperature and typical weather patterns in a place. Climate change could refer to a particular location or the planet as a whole. Climate change may cause weather patterns to be less predictable. A region might experience lower or higher than average temperatures. Climate change may cause more frequent and severe weather events, such as storms, floods and droughts.

What are the Causes of Climate Change?

The main cause of climate change is human activity. The burning of fossil fuels, such as coal, oil and gas, releases greenhouse gases into the atmosphere. Greenhouse gases trap heat from the sun, which warms the planet. Other human activities that contribute to climate change include deforestation, agriculture and industrial processes.

What are the effects of climate change?

Climate change is already having a significant impact on the planet. The average global temperature has increased by about 1 degree Celsius since the late 19th century. This warming is causing sea levels to rise, Glaciers to melt and extreme weather events to become more common. Climate change is also having a negative impact on human Health, agriculture and Ecosystems.

What can be done to address climate change?

There are a number of things that can be done to address climate change. These include reducing greenhouse gas emissions, investing in RENEWABLE ENERGY sources, improving Energy Efficiency and protecting forests. It is also important to adapt to the impacts of climate change, such as by building sea walls to protect coastal communities from rising sea levels.

What is Global Warming?

Global warming is the long-term heating of Earth’s climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere. The term is frequently used interchangeably with the term climate change, though the latter refers to both human- and naturally produced warming and the effects it has on our planet. It is most commonly measured as the average increase in Earth’s global surface temperature.

What are the causes of global warming?

The primary cause of global warming is human activity. The burning of fossil fuels, such as coal, oil and natural gas, releases greenhouse gases into the atmosphere. Greenhouse gases trap heat from the sun, which warms the planet. Other human activities that contribute to global warming include deforestation, agriculture and industrial processes.

What are the effects of global warming?

Global warming is already having a significant impact on the planet. The average global temperature has increased by about 1 degree Celsius since the late 19th century. This warming is causing sea levels to rise, glaciers to melt and extreme weather events to become more common. Global warming is also having a negative impact on human health, agriculture and ecosystems.

What can be done to address global warming?

There are a number of things that can be done to address global warming. These include reducing greenhouse gas emissions, investing in renewable energy sources, improving energy efficiency and protecting forests. It is also important to adapt to the impacts of global warming, such as by building sea walls to protect coastal communities from rising sea levels.

What is the difference between climate change and global warming?

Climate change is a long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates. These changes have a broad range of observed effects that are synonymous with the term. Climate change may cause weather patterns to be less predictable. A region might experience lower or higher than average temperatures. Climate change may cause more frequent and severe weather events, such as storms, floods and droughts.

In short, climate change is a broader term that refers to any long-term change in Earth’s climate, while global warming is a specific type of climate change that is caused by human activities.

What is the name of the current climate pattern that is causing extreme weather events around the world?
(A) El NiÃ±o
(B) La NiÃ±a
(C) The Pacific Decadal Oscillation
(D) The Atlantic Multidecadal Oscillation
What is the main difference between El NiÃ±o and La NiÃ±a?
(A) El NiÃ±o is a warming of the Pacific Ocean, while La NiÃ±a is a cooling of the Pacific Ocean.
(B) El NiÃ±o occurs every few years, while La NiÃ±a occurs every few decades.
(C) El NiÃ±o is associated with droughts in the southern hemisphere, while La NiÃ±a is associated with floods in the southern hemisphere.
(D) El NiÃ±o is associated with warmer temperatures in the northern hemisphere, while La NiÃ±a is associated with cooler temperatures in the northern hemisphere.
What are some of the effects of El NiÃ±o and La NiÃ±a on the Environment?
(A) El NiÃ±o can cause droughts in the southern hemisphere and floods in the northern hemisphere.
(B) La NiÃ±a can cause floods in the southern hemisphere and droughts in the northern hemisphere.
(C) El NiÃ±o and La NiÃ±a can both cause droughts and floods in different parts of the world.
(D) El NiÃ±o and La NiÃ±a have no significant effects on the environment.
What are some of the effects of El NiÃ±o and La NiÃ±a on human society?
(A) El NiÃ±o can cause crop failures and famine.
(B) La NiÃ±a can cause flooding and landslides.
(C) El NiÃ±o and La NiÃ±a can both cause crop failures, famine, flooding, and landslides.
(D) El NiÃ±o and La NiÃ±a have no significant effects on human society.
How can we predict El NiÃ±o and La NiÃ±a?
(A) We can predict El NiÃ±o and La NiÃ±a by observing the temperature of the Pacific Ocean.
(B) We can predict El NiÃ±o and La NiÃ±a by observing the pressure of the atmosphere.
(C) We can predict El NiÃ±o and La NiÃ±a by observing the amount of rainfall.
(D) We can predict El NiÃ±o and La NiÃ±a by observing the amount of snowmelt.
What are some of the ways that we can mitigate the effects of El NiÃ±o and La NiÃ±a?
(A) We can build seawalls to protect coastal communities from flooding.
(B) We can develop drought-resistant crops.
(C) We can improve early warning systems to help people prepare for extreme weather events.
(D) All of the above.
What are some of the long-term effects of El NiÃ±o and La NiÃ±a?
(A) El NiÃ±o and La NiÃ±a can cause changes in sea level.
(B) El NiÃ±o and La NiÃ±a can cause changes in precipitation patterns.
(C) El NiÃ±o and La NiÃ±a can cause changes in temperature patterns.
(D) All of the above.
What are some of the ways that we can adapt to the long-term effects of El NiÃ±o and La NiÃ±a?
(A) We can develop new agricultural practices that are more resilient to drought and flooding.
(B) We can develop new Infrastructure-2/”>INFRASTRUCTURE that can withstand extreme weather events.
(C) We can improve our understanding of the climate system so that we can better predict El NiÃ±o and La NiÃ±a events.
(D) All of the above.
What are some of the challenges that we face in mitigating and adapting to the effects of El NiÃ±o and La NiÃ±a?
(A) El NiÃ±o and La NiÃ±a are complex climate phenomena that are difficult to predict.
(B) The effects of El NiÃ±o and La NiÃ±a are often felt in remote and vulnerable communities.
(C) There is a lack of funding for research on El NiÃ±o and La NiÃ±a.
(D) All of the above.
What can we do to help mitigate and adapt to the effects of El NiÃ±o and La NiÃ±a?
(A) We can educate ourselves about El NiÃ±o and La NiÃ±a.
(B) We can support research on El NiÃ±o and La NiÃ±a.
(C) We can advocate for policies that will help us mitigate and adapt to the effects of El NiÃ±o and La NiÃ±a.
(D) All of the above.