The direction of the El Niño current is South America. Hydrology
Must retreat. It is being replaced by a diametrically opposite phenomenon - La Niña. And if the first phenomenon can be translated from Spanish as “child” or “boy,” then La Niña means “girl.” Scientists hope that the phenomenon will help to somewhat balance the climate in both hemispheres, lowering the average annual temperature, which is now rapidly rising.
What are El Nino and La Nina
El Niño and La Niña are warm and cold currents or opposing extremes of water temperature and atmospheric pressure characteristic of the equatorial Pacific Ocean that last about six months.
Phenomenon El Niño consists of a sharp increase in temperature (by 5-9 degrees) of the surface layer of water in the eastern Pacific Ocean over an area of about 10 million square meters. km.
La Niña- the opposite of El Niño - manifests itself as a decrease in surface water temperature below the climate norm in the eastern tropical zone of the Pacific Ocean.
Together they constitute the so-called Southern Oscillation.
How does El Niño form? Near the Pacific coast of South America there is a cold Peruvian Current, which arises due to the trade winds. About once every 5-10 years, the trade winds weaken for 1-6 months. As a result, the cold current stops its “work”, and warm waters shift to the shores of South America. This phenomenon is called El Niño. El Niño energy can lead to disturbances in the entire atmosphere of the Earth, provokes environmental disasters, the phenomenon is involved in numerous weather anomalies in the tropics, which often lead to material losses and even human casualties.
What will La Niña bring to the planet?
Just like El Niño, La Niña appears with a certain cyclicity from 2 to 7 years and lasts from 9 months to a year. For residents of the Northern Hemisphere, the phenomenon threatens a decrease in winter temperatures by 1-2 degrees, which in current conditions is not so bad. Considering that the Earth has shifted, and now spring comes 10 years earlier than 40 years ago.
It should also be noted that El Niño and La Niña do not necessarily have to replace each other - there can often be several “neutral” years between them.
But don't expect La Niña to come quickly. Judging by observations, this year will be under the rule of El Niño, as evidenced by monthly data on both a planetary and local scale. “Girl” will begin to bear fruit no earlier than 2017.
The mechanisms that may cause El Niño events are still being researched. It is difficult to find patterns that can reveal causes or allow predictions to be made.
Bjerknes in 1969 suggested that abnormal warming in the eastern Pacific Ocean may be attenuated by east-west temperature differences, causing weakening in the Volcker circulation and trade winds that move warm water westward. The result is an increase in warm water to the east.
Virtki in 1975 suggested that the trade winds could create a westerly bulge of warm waters, and any weakening of the winds could allow warm waters to move east. However, no bulges were noticed on the eve of the events of 1982-83. .
Rechargeable Oscillator: Some mechanisms have been proposed that when warm areas are created in the equatorial region, they are dissipated to higher latitudes through El Niño events. The cooled areas are then recharged with heat for several years before the next event occurs.
Western Pacific Oscillator: In the western Pacific Ocean, several weather conditions could cause easterly wind anomalies. For example, a cyclone in the north and an anticyclone in the south result in an easterly wind between them. Such patterns can interact with the westerly flow across the Pacific Ocean and create a tendency for the flow to continue eastward. A weakening of the westerly current at this time may be the final trigger.
The equatorial Pacific Ocean can lead to El Niño-like conditions with a few random variations in behavior. External weather patterns or volcanic activity can be such factors.
The Madden-Julian Oscillation (MJO) is a critical source of variability that may contribute to the sharper evolution leading to El Niño conditions through fluctuations in low-level winds and precipitation over the western and central regions. Pacific Ocean. The eastward propagation of oceanic Kelvin waves may be caused by MJO activity.
2. Southern Oscillation and El Niño
The Southern Oscillation and El Niño (Spanish El Niño - Baby, Boy) is a global ocean-atmospheric phenomenon. A characteristic feature of the Pacific Ocean, El Niño and La Niña are temperature fluctuations in surface waters in the tropical eastern Pacific Ocean. The names for these phenomena, borrowed from the native Spanish and first coined in 1923 by Gilbert Thomas Volcker, mean "baby" and "little one," respectively. Their influence on the climate of the southern hemisphere is difficult to overestimate. The Southern Oscillation (the atmospheric component of the phenomenon) reflects monthly or seasonal fluctuations in the difference in air pressure between the island of Tahiti and the city of Darwin in Australia.
The circulation named after Volcker is a significant aspect of the Pacific phenomenon ENSO (El Niño Southern Oscillation). ENSO is many interacting parts of one global system of ocean-atmospheric climate fluctuations that occur as a sequence of oceanic and atmospheric circulations. ENSO is the world's best known source of interannual weather and climate variability (3 to 8 years). ENSO has signatures in the Pacific, Atlantic and Indian Oceans.
In the Pacific, during significant warm events, El Niño warms up and expands across much of the Pacific tropics and becomes directly correlated with SOI (Southern Oscillation Index) intensity. While ENSO events occur primarily between the Pacific and Indian Oceans, ENSO events in the Atlantic Ocean lag behind the former by 12 to 18 months. Most of the countries that experience ENSO events are developing ones, with economies that are heavily dependent on the agricultural and fishing sectors. New capabilities to predict the onset of ENSO events in three oceans could have global socioeconomic implications. Since ENSO is a global and natural part of the Earth's climate, it is important to know whether changes in intensity and frequency could be a result of global warming. Low frequency changes have already been detected. Interdecadal ENSO modulations may also exist (Fig. 1)
Fig.1. El Niño and La Niña
Common Pacific pattern. Equatorial winds collect a warm pool of water to the west. Cold waters rise to the surface along the South American coast. (NOAA/PMEL/TAO)
El Niño and La Niña are officially defined as long-lasting marine surface temperature anomalies greater than 0.5 °C crossing the central tropical Pacific Ocean. When a condition of +0.5 °C (-0.5 °C) is observed for a period of up to five months, it is classified as an El Niño (La Niña) condition. If the anomaly persists for five months or longer, it is classified as an El Niño (La Niña) episode. The latter occurs at irregular intervals of 2-7 years and usually lasts one or two years.
The first signs of El Niño are as follows:
1. Increase in air pressure over the Indian Ocean, Indonesia and Australia.
2. A drop in air pressure over Tahiti and the rest of the central and eastern parts of the Pacific Ocean.
3. Trade winds in the South Pacific are weakening or heading east.
4. Warm air appears near Peru, causing rain in the deserts.
5. Warm water spreads from the western part of the Pacific Ocean to the eastern. It brings rain with it, causing it to occur in areas that are usually dry.
The warm El Niño current, composed of plankton-poor tropical water and heated by its eastern flow in the Equatorial Current, replaces the cold, plankton-rich waters of the Humboldt Current, also known as the Peruvian Current, which supports large populations of game fish. Most years, the warming lasts only a few weeks or months, after which weather patterns return to normal and fish catches increase. However, when El Niño conditions last for several months, more extensive ocean warming occurs and its economic impact on local fisheries for the external market can be severe.
The Volcker circulation is visible on the surface as easterly trade winds, which move water and air heated by the sun westward. It also creates oceanic upwelling off the coasts of Peru and Ecuador, bringing cold plankton-rich waters to the surface, increasing fish populations. The western equatorial Pacific Ocean is characterized by warm, humid weather and low atmospheric pressure. The accumulated moisture falls in the form of typhoons and storms. As a result, in this place the ocean is 60 cm higher than in its eastern part.
In the Pacific Ocean, La Niña is characterized by unusually cold temperatures in the eastern equatorial region compared to El Niño, which in turn is characterized by unusually warm temperatures in the same region. Atlantic tropical cyclone activity generally increases during La Niña. A La Niña condition often occurs after an El Niño, especially when the latter is very strong.
Traces of destruction caused by El Niño :
1.1525: First historical mention of El Niño in Peru.
2.1789-1793: El Niño killed 600,000 people in India and caused severe famine in South Africa.
3.1982-1983: This phenomenon caused the death of 2,000 people and caused damage, especially in tropical regions, amounting to US$13 billion.
4.1990-1995: Three incidents occurred one after another, making up one of the longest recorded El Niño events.
5.1997-1998: Despite early success in regional flood and drought forecasting, El Niño caused approximately 2,100 deaths and $33 billion in damages worldwide.
Typically, trade winds drive a layer of warm water from the American coast towards Asia. Around Indonesia, the current stops. The ocean surface level there at this time exceeds the mark off the Peruvian coast by 60 centimeters. Clouds form over the warming ocean and typically fall as monsoon rains over southern Asia. But when El Niño “shows character”, the trade winds weaken or do not blow at all. The heated water spreads to the sides and goes back to the American coast. Researchers now understand this phenomenon and call it the Southern Oscillation. They, as if in a bathtub, rock the heated ocean waters from west to east and back. Only in the ocean all this happens much more slowly than in a bath. Behind the swaying water, as if accompanying it, are rain clouds, which usually rained in September-October over Indonesia and Australia.
In the early spring of 1997, space satellites armed with infrared cameras showed that a patch of heated water had formed near the equator in the eastern Pacific Ocean. The 10-12 centimeter thick layer had a temperature of up to 30 degrees Celsius - 5 degrees higher than usual. This alerted meteorologists. The center of a tropical typhoon system could form here. Warmer water could weaken trade winds or reverse them, thereby increasing the destructive effects of El Niño, as was the case in 1982.
When then, in June, the difference in atmospheric pressure over the Australian port of Darwin and over the island of Tahiti changed significantly (southern oscillation), and Peruvian fishermen in their waters, to everyone’s surprise, caught a pair of hammerhead sharks (fish that live in very warm waters) , the weather service and the media sounded the alarm.
The reasons for this were: a change in atmospheric pressure over the equatorial region of the Pacific Ocean - a sign that the current there had reversed. That's why heat-loving sharks ended up off the coast of Peru.
Another month and a half passed, and new facts emerged confirming the worst fears: corals, creatures that are very sensitive to water temperature, began to die off the coast of Mexico and Costa Rica. In Chile, hungry cormorants have begun raiding fish markets. In Peru, due to a lack of raw materials, several factories that processed fish into flour had to be closed. Heavy rains hit Chile, followed by a rat infestation. Viruses brought by rats caused outbreaks of disease. The oldest buildings in South America - pyramids made of unfired brick - fell victim to the rains. Many of them are about 1500 years old. And now they may be washed away by water pouring from the sky. Scientists sounded the alarm. Roofs made of canvas and plastic are being urgently built over the monuments.
Some archaeologists are already saying that El Niño in the distant past could have been one of the reasons for the death of the highly developed cultures of the peoples of South America. Archaeologist Ricardo Morales suggested that in the years 550 - 600 A.D. the famous Pyramid of the Moon was washed away by rains caused, as he believes, by a super-strong El Niño. The village, located not far from the pyramid, according to the scientist, was washed away by streams of water.
In Peru, according to archaeologist M. Moseli, 1100 years ago, a powerful El Niño, or rather, the natural disasters generated by it, destroyed the system of irrigation canals and thereby destroyed the highly developed culture of a large state.
3. Study of the El Niño phenomenon
The first European to swim across the largest ocean on the planet was Magellan. He called him "Quiet". As it soon became clear, Magellan was mistaken. It is in this ocean that most typhoons are born, and it produces three-quarters of the planet's clouds. Now we have also learned that the El Niño current emerging in the Pacific Ocean sometimes causes many different troubles and disasters on the planet.
The current stretches from the coast of Peru to the archipelago surrounding the Southeast of the Asian continent. In terms of El Niño, it is an elongated tongue of highly heated water. It is equal in area to the United States. Heated water evaporates more intensely and “pumps” the atmosphere with energy faster. El Niño supplies it with 450 million megawatts, which is equivalent to the power of 300,000 large nuclear power plants. It is clear that this energy, according to the law of conservation of energy, does not disappear. And now in Indonesia, disaster broke out in full force. First, there was a raging drought on the island of Sumatra, then the dried-out forests began to burn. In the impenetrable smoke that enveloped the entire island, the plane crashed upon landing, and a tanker and a cargo ship collided at sea. The smoke reached Singapore and Malaysia... El Niño is also to blame for all this.
And to the American Pacific coast the current brought prolonged rain and hurricanes with hail. A state of emergency had to be declared in Costa Rica, Bolivia and Peru. South Africa is threatened by drought, and in Australia it has already devastated farmers' fields and meadows. In many places on earth, crops were completely destroyed.
Lack of water has reached the latitudes of Central America. Because of it, Lake Gatuk, part of the Panama Canal route, became shallow. It is filled with the runoff of rivers flowing towards the Atlantic. Due to the large landmass, the rivers have become scarce, the lake has become shallow, and now only ships with a shallow draft can pass through the Panama Canal.
The phenomenon, the origin of which is still unknown, repeats itself every six or seven years.
During the winter of 1997-1998, images of flooded villages, reports of heavy rains in various parts of the planet and abnormal temperatures in the United States and South America became a common sight on television screens and the pages of all newspapers. These events were associated with a phenomenon called El Niño.
However, the appearance of El Niño in 1997 and 1998 did not come as a surprise to meteorologists and people interested in this phenomenon. Since 1923, it has been the subject of close study. His name, meaning "little boy", came from South American fishermen, as his appearance coincided with the advent of Christmas - the time of the birth of little Jesus. During El Niño, an unusually high temperature is observed in the equatorial waters of the Pacific Ocean, which under normal conditions does not exceed 0.5 C. Temperature changes are associated with changes in pressure, as a result of which the winds blowing here also change direction. Due to rising water temperatures, squally winds often occur, especially in the Pacific Ocean on both its western and eastern coasts.
Unlike other parts of the world, South America is most affected by El Niño. Summer here has become hot and humid, with heavy rainfall on the coasts of Peru and Ecuador. From December 1997 to February 1998, there were serious floods.
Three months later, similar phenomena could be observed in northern Argentina and southern Brazil. As for Brazil, Rio de Janeiro still cannot recover from the terrible consequences of the flood.
Chile and the Bolivian Altiplano, on the other hand, experienced an incredibly harsh winter with snow storms and temperatures below normal. Northern Amazonia, Colombia and Central America experienced an unusually dry summer.
In the opposite part of the Pacific Ocean, similar phenomena also occurred, but on a slightly smaller scale. Indonesia, the Philippines and Australia received less rainfall than in previous decades.
The United States and Canada have experienced rising and falling temperatures. The Midwest and Canada experienced warm winters, while Southern California, Northwestern Mexico and several US states suffered from persistent rain.
Africa also had to deal with climate changes caused by El Niño. December through February was unusually wet for Equatorial Africa and Southern Sahara. In contrast to these areas of the African continent, Zambia, Zimbabwe, Mozambique and Botswana were surprised by hot, humid weather. Incessant rains caused floods on the American continent, and landslides became more frequent, causing serious material damage and 800 casualties.
In South America, climate change has caused the spread of cholera, dengue, malaria, encephalitis and leptospirosis, which, combined with poor health conditions, often cause high mortality rates in developing countries. Just like it happened in 1991, when during another El Niño visit there was an outbreak of cholera that claimed 12,000 lives.
The fishing industry is experiencing the most negative consequences of weather changes. With the advent of El Niño, cold currents rich in food for fish and birds are displaced. The decline in bird populations in the coastal zone poses certain dangers, as their excrement is used in the production of fertilizers. El Niño has a corresponding negative impact on the situation of fish processing enterprises. Surprisingly, while the fishing industry is in decline, life in the suburbs is improving significantly. The warm climate has a beneficial effect on the harvest, and local farmers can relax a little.
The El Niño phenomenon is nothing more than the southern oscillation, which is a significant fluctuation in water and air temperature in the South Pacific Ocean, off the coast of South America. Such fluctuations (oscillations) occur very irregularly - once every three, four, or even five years. The maximum development of the southern oscillations usually occurs in December, on Christmas Eve, and is accompanied by a strong increase in fish catch. That is why South Americans, especially Peruvians, are looking forward to the next oscillation with great impatience.
The El Niño phenomenon, as already mentioned, is characterized by a high degree of uncertainty. However, in recent years, there has been an opinion that they have already learned how to predict El Niño. The last cases of El Niño in 1986-1991 were predicted in advance and with a sufficient degree of accuracy by S. Zebiak. Together with M. Kapel, S. Zebiak developed a forecast according to which the arrival of El Niño in 1993 was not expected.
Some scientists admit that this course of events has dealt a serious blow to mathematical modeling.
US President Clinton convened a council in October 1997 that examined all aspects of the unfolding environmental disaster. A task was formulated: all industrial enterprises in the country that discharge greenhouse gases into the atmosphere should reduce their emissions by the year 2000 to the 1990 level.
Meteorologists' predictions have been confirmed: catastrophic events associated with the El Niño current are hitting the earth one after another. Of course, it is very sad that all this is happening now. But still, it should be noted that for the first time humanity is encountering a global natural disaster, knowing its causes and the course of further development.
The El Niño phenomenon is already quite well studied. Science has solved the mystery that plagued Peruvian fishermen. They did not understand why sometimes during the Christmas period the ocean becomes warmer and the shoals of sardines off the coast of Peru disappear. Because the arrival of warm water coincided with Christmas, the current was called El Niño, which means "baby boy" in Spanish.
Fishermen, of course, are interested in the immediate reason for the departure of the sardines. The fact is that sardines (and not only them) feed on phytoplankton, a component of which is microscopic algae. And algae need sunlight and nutrients - primarily nitrogen and phosphorus. They are present in ocean water, and their supply in the upper layer is constantly replenished by vertical currents going from the bottom to the surface. But when the El Niño current turns back towards South America, its warm waters “block” the exit of deep waters. Biogenic elements do not rise to the surface, and algae reproduction stops. The fish leave these places - they do not have enough food.
Even in those years when El Niño does not bring great trouble, it is worth keeping an eye on it, since it contains and encodes the future development of the atmosphere: what to expect from the next winter, whether spring will be early or late, whether there is a threat of summer drought.
Factors such as wind, clouds, rain, sunny skies help predict the weather only for the near future. Several days will pass, and new winds and new clouds will determine the weather. Only the oceans have a long-term influence on the atmosphere. And they are the ones who determine the weather on Earth.
For more than 15 years, the joint work of climatologists, meteorologists, and oceanologists from around the world has continued, trying to find the basis for long-term weather forecasts. They installed buoys with instruments in the oceans, sank them to depth, and monitored the behavior of sea waters from satellites. The entire mass of extracted digital material was loaded into computers... The warning received from scientists that catastrophic weather changes were possible at the end of 1997 shows that all this complex and expensive research was not carried out in vain. German meteorologist M. Latif states: “We understand the essence of the phenomenon.”
Droughts, storms, floods, and colds have significantly influenced the fate of entire nations in all centuries. Stories about these very real events of distant times gradually turned into legends and myths. And now many of them are receiving a scientific explanation.
El Niño, a warm seasonal flow of surface water of low salinity in the eastern Pacific Ocean. Distributed in the summer of the Southern Hemisphere along the coast of Ecuador from the equator to 5-7° south. w. In some years, E. - N. intensifies and, penetrating far to the south (up to 15° S), pushes cold waters away from the coast. A thin layer of warm waters from the E. - N. stops the supply of oxygen to the subsurface layers, which has a detrimental effect on the plankton and fish of the richest Peruvian productive region; heavy rainfall causes catastrophic flooding on the normally dry coast.
The penetration of warm waters into the south is associated with the weakening of the action of trade winds and the cessation of the rise of cold subsurface waters to the surface in the coastal part of the ocean. Usually this catastrophic phenomenon is observed in late December - early January. It manifested itself especially sharply in 1891, 1925, 1941, 1953, 1957-58 and 1972-73. During the years of development of E. - N., fish (anchovy) either die or leave coastal waters, which causes a high mortality rate of seabirds feeding on fish and reduces the amount of guano used as food. - X. fertilizers
An analysis of historical oceanographic, meteorological, heliogeophysical and geodynamic data was performed. Main results obtained:
Large-scale phenomena in the ocean and atmosphere of the Earth are closely related to each other, being direct factors of weather and climate fluctuations. In turn, these factors are a reflection of external (cosmic) influences: solar activity, interplanetary magnetic field and dissymmetry of the solar system, the latter being the guiding factor, affecting the influx of light radiation from the Sun to the Earth, changes in the speed of the Earth’s orbital and axial rotation, and precession of the earth's axis.
The speed of rotation of the Earth is associated with the magnitude of the angular momentum of the motion of the atmosphere in relation to the earth's surface (circulation index according to E.I. Blinova). It is shown that with an increase in the circulation index, the centers of atmospheric action over the oceans (the Azores and Honolulu anticyclones) shift southward.
As a result of the displacement of anticyclones to the south, the atmospheric pressure gradient between them and the equatorial zone increases (an increase in the Southern Oscillation index in the Pacific Ocean and the North-South Oscillation in the subtropical Atlantic zone). In these zones of increased atmospheric pressure gradients, trade winds intensify, drawing the surface waters of the oceans in the western and northwestern directions and, as a consequence, the appearance of low temperatures on the surface of the Pacific Ocean near the equator in its central and eastern parts.
The US National Oceanic and Atmospheric Administration (NOAA) has declared an El Niño (Spanish for "boy") in the Pacific Ocean. As reported, the climate phenomenon is characterized by an increase in the temperature of the surface layers of water by at least 0.5 degrees Celsius.
Currently, temperatures in this region of the Pacific Ocean are almost a degree above average for this time period. NOAA promises that El Niño will last until the spring of 2010. Officially, the last time El Niño occurred was in 2006.
Possible climate effects caused by El Niño include harsh winters in California, accompanied by snow storms, and drought in Indonesia. In addition, "Boy" can lead to floods in South and Central America. However, not all climate effects of El Niño are negative. Thus, among the advantages of this phenomenon are weaker hurricane seasons (the first hurricane of the new season recently formed).
Most recently, the American Space Agency provided Internet users with the opportunity to observe changes in the temperature of the oceans in real time using the Sea Level Viewer website. When you visit this resource, made using Flash technology, an interactive globe appears, which displays data on water temperature. In particular, the presence of El Niño is separately displayed there.
As previously reported, the earth has warmed by 0.4 degrees Celsius over the past 30 years, according to data obtained from NASA satellites and the American weather agency NOAA.
A map of temperature changes since December 1, 1978, when satellites began collecting data, shows that the level of warming has not been the same across the planet. Half the globe warmed by at least 0.3 degrees Celsius during this period, while a quarter of the Earth became 0.6 degrees warmer.
The strongest warming occurred in the North Atlantic and Arctic. The temperature rose the highest in one of the regions of Greenland - by more than 2.5 degrees.
One of the most prominent features of the 30-year temperature curve is the warming in 1997-1998 associated with El Niño, an anomalous warming of surface water in the eastern Pacific Ocean that affects the climate of the entire Western Hemisphere. The opposite phenomenon, La Niña, is associated, on the contrary, with anomalous cooling of water.
Conclusion
Unfortunately, the causes of El Niño still remain unknown, as are the consequences caused by global climate change. The repetition of this phenomenon is observed every six or seven years. Its duration depends on a number of factors, which meteorologists are currently studying.
The events of 1997-1998 caused La Niña. This natural phenomenon occurs when climate changes caused by El Niño become particularly noticeable. La Niña is the exact opposite of El Niño. Where one causes temperatures to rise, the other causes them to fall. While El Niño brings rain, La Niña brings drought.
On the coast of South America, La Nina is greeted with joy: with a decrease in the temperature of the current, more fish come and, consequently, catches increase. But in agriculture, the opposite is true: La Niña is not popular because the drop in temperature it causes has an adverse effect on crops.
In recent times, especially since 1982-1983, when the impact of El Niño was at its strongest, and also in 1990-1994, its longest period of influence, countries dependent on the vagaries of nature have relied entirely on weather forecasting.
Without a doubt, only an accurate forecast helps plan the harvest and the workload of the fishing fleet. And governments of different countries can develop plans for timely provision of financial assistance to various sectors of the economy.
So, an unusually complex and branched system of direct and feedback connections allows us to talk about the Earth as a single living organism in which everything is very finely balanced.
Bibliography
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The circulation named after Volcker is a significant aspect of the Pacific phenomenon ENSO (El Nino Southern Oscillation). ENSO is many interacting parts of one global system of ocean-atmospheric climate fluctuations that occur as a sequence of oceanic and atmospheric circulations. ENSO is the world's best known source of interannual weather and climate variability (3 to 8 years). ENSO has signatures in the Pacific, Atlantic and Indian Oceans.
In the Pacific, during significant warm events, El Niño warms up and expands across much of the Pacific tropics and becomes directly correlated with SOI (Southern Oscillation Index) intensity. While ENSO events occur primarily between the Pacific and Indian Oceans, ENSO events in the Atlantic Ocean lag behind the former by 12 to 18 months. Most of the countries that experience ENSO events are developing ones, with economies that are heavily dependent on the agricultural and fishing sectors. New capabilities to predict the onset of ENSO events in three oceans could have global socioeconomic implications. Since ENSO is a global and natural part of the Earth's climate, it is important to know whether changes in intensity and frequency could be a result of global warming. Low frequency changes have already been detected. Interdecadal ENSO modulations may also exist.
El Niño and La Niña
Common Pacific pattern. Equatorial winds collect a warm pool of water to the west. Cold waters rise to the surface along the South American coast.AND La Niña officially defined as long-lasting marine surface temperature anomalies greater than 0.5 °C crossing the central tropical Pacific Ocean. When a condition of +0.5 °C (-0.5 °C) is observed for a period of up to five months, it is classified as an El Niño (La Niña) condition. If the anomaly persists for five months or longer, it is classified as an El Niño (La Niña) episode. The latter occurs at irregular intervals of 2-7 years and usually lasts one or two years.
Increase in air pressure over the Indian Ocean, Indonesia and Australia.
A drop in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean.
Trade winds in the South Pacific are weakening or heading east.
Warm air appears near Peru, causing rain in the deserts.
Warm water spreads from the western part of the Pacific Ocean to the eastern. It brings rain with it, causing it to occur in areas that are usually dry.
Warm El Niño current, consisting of plankton-poor tropical water and heated by its eastern outlet in the Equatorial Current, replaces the cold, plankton-rich waters of the Humboldt Current, also known as the Peruvian Current, which contains large populations of game fish. Most years, the warming lasts only a few weeks or months, after which weather patterns return to normal and fish catches increase. However, when El Niño conditions last for several months, more extensive ocean warming occurs and its economic impact on local fisheries for the external market can be severe.
The Volcker circulation is visible on the surface as easterly trade winds, which move water and air heated by the sun westward. It also creates oceanic upwelling off the coasts of Peru and Ecuador, bringing cold plankton-rich waters to the surface, increasing fish populations. The western equatorial Pacific Ocean is characterized by warm, humid weather and low atmospheric pressure. The accumulated moisture falls in the form of typhoons and storms. As a result, in this place the ocean is 60 cm higher than in its eastern part.
In the Pacific Ocean, La Niña is characterized by unusually cold temperatures in the eastern equatorial region compared to El Niño, which in turn is characterized by unusually warm temperatures in the same region. Atlantic tropical cyclone activity generally increases during La Niña. A La Niña condition often occurs after an El Niño, especially when the latter is very strong.
Southern Oscillation Index (SOI)
The Southern Oscillation Index is calculated from monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.Long-lasting negative SOI values often signal El Niño episodes. These negative values typically accompany continued warming of the central and eastern tropical Pacific, decreased strength of the Pacific trade winds, and decreased rainfall in eastern and northern Australia.
Positive SOI values are associated with strong Pacific trade winds and warming water temperatures in northern Australia, well known as a La Niña episode. The waters of the central and eastern tropical Pacific Ocean become colder during this time. Together this increases the likelihood of more rainfall than normal in eastern and northern Australia.
El Niño influence
As El Niño's warm waters fuel storms, it creates increased precipitation in the east-central and eastern Pacific Ocean.In South America, the El Niño effect is more pronounced than in North America. El Niño is associated with warm and very wet summer periods (December-February) along the coast of northern Peru and Ecuador, causing severe flooding whenever the event is severe. The effects during February, March, April may become critical. Southern Brazil and northern Argentina also experience wetter than normal conditions, but mainly during the spring and early summer. The central region of Chile receives mild winters with plenty of rain, and the Peruvian-Bolivian Plateau sometimes experiences winter snowfall, which is unusual for the region. Drier and warmer weather is observed in the Amazon Basin, Colombia and Central America.
Direct effects of El Niño leading to decreased humidity in Indonesia, increasing the likelihood of forest fires, in the Philippines and northern Australia. Also in June-August, dry weather is observed in the regions of Australia: Queensland, Victoria, New South Wales and eastern Tasmania.
The western Antarctic Peninsula, Ross Land, Bellingshausen and Amundsen seas are covered with large amounts of snow and ice during El Niño. The latter two and the Wedell Sea become warmer and are under higher atmospheric pressure.
In North America, winters are generally warmer than normal in the Midwest and Canada, while central and southern California, northwestern Mexico and the southeastern United States are getting wetter. The Pacific Northwest states, in other words, dry out during El Niño. Conversely, during La Niña, the US Midwest dries out. El Niño is also associated with decreased hurricane activity in the Atlantic.
Eastern Africa, including Kenya, Tanzania and the White Nile Basin, experiences long periods of rain from March to May. Droughts plague southern and central Africa from December to February, mainly Zambia, Zimbabwe, Mozambique and Botswana.
Warm Pool of the Western Hemisphere. A study of climate data showed that approximately half of the post-El Niño summers experienced unusual warming in the Western Hemisphere Warm Pool. This influences the weather in the region and appears to have a connection to the North Atlantic Oscillation.
Atlantic effect. An El Niño-like effect is sometimes observed in the Atlantic Ocean, where water along the equatorial African coast becomes warmer and water off the coast of Brazil becomes colder. This can be attributed to the Volcker circulation over South America.
Non-climatic effects of El Niño
Along the east coast of South America, El Niño reduces the upwelling of cold, plankton-rich water that supports large populations of fish, which in turn support an abundance of seabirds, whose droppings support the fertilizer industry.Local fishing industries along coastlines may experience shortages of fish during prolonged El Niño events. The world's largest fisheries collapse due to overfishing, which occurred in 1972 during El Niño, led to a decline in the Peruvian anchovy population. During the events of 1982-83, populations of southern horse mackerel and anchovies declined. Although the number of shells in warm water increased, hake went deeper into cold water, and shrimp and sardines went south. But the catch of some other fish species was increased, for example, the common horse mackerel increased its population during warm events.
Changing locations and types of fish due to changing conditions have presented challenges for the fishing industry. The Peruvian sardine has moved towards the Chilean coast due to El Niño. Other conditions have only led to further complications, such as the Chilean government creating fishing restrictions in 1991.
It is postulated that El Niño led to the extinction of the Indian Mochico tribe and other tribes of the pre-Columbian Peruvian culture.
Causes that give rise to El Niño
The mechanisms that may cause El Niño events are still being researched. It is difficult to find patterns that can reveal causes or allow predictions to be made.Bjerknes suggested in 1969 that abnormal warming in the eastern Pacific Ocean could be attenuated by east-west temperature differences, causing weakening in the Volcker circulation and trade winds that move warm water westward. The result is an increase in warm water to the east.
Virtky in 1975 suggested that the trade winds could create a westerly bulge of warm waters, and any weakening of the winds could allow warm waters to move east. However, no bulges were noticed on the eve of the events of 1982-83.
Rechargeable Oscillator: Some mechanisms have been proposed that when warm areas are created in the equatorial region, they are dissipated to higher latitudes through El Niño events. The cooled areas are then recharged with heat for several years before the next event occurs.
Western Pacific Oscillator: In the western Pacific Ocean, several weather conditions could cause easterly wind anomalies. For example, a cyclone in the north and an anticyclone in the south result in an easterly wind between them. Such patterns can interact with the westerly flow across the Pacific Ocean and create a tendency for the flow to continue eastward. A weakening of the westerly current at this time may be the final trigger.
The equatorial Pacific Ocean can lead to El Niño-like conditions with a few random variations in behavior. External weather patterns or volcanic activity can be such factors.
The Madden-Julian Oscillation (MJO) is a critical source of variability that may contribute to the sharper evolution leading to El Niño conditions through fluctuations in low-level winds and precipitation over the western and central regions. Pacific Ocean. The eastward propagation of oceanic Kelvin waves may be caused by MJO activity.
History of El Niño
The first mention of the term "El Niño" dates back to 1892, when Captain Camilo Carrilo reported at the Congress of the Geographical Society in Lima that Peruvian sailors called the warm northerly current "El Niño" because it was most noticeable around Christmas. However, even then the phenomenon was interesting only because of its biological impact on the efficiency of the fertilizer industry.Normal conditions along the western Peruvian coast are a cold southerly current (Peruvian Current) with upwelling water; plankton upwelling leads to active ocean productivity; cold currents lead to a very dry climate on earth. Similar conditions exist everywhere (California Current, Bengal Current). So replacing it with a warm northern current leads to a decrease in biological activity in the ocean and to heavy rains leading to flooding on land. The connection with flooding was reported in 1895 by Pezet and Eguiguren.
Towards the end of the nineteenth century there was increased interest in predicting climate anomalies (for food production) in India and Australia. Charles Todd suggested in 1893 that droughts in India and Australia occur at the same time. Norman Lockyer pointed out the same thing in 1904. In 1924, Gilbert Volcker first coined the term "Southern Oscillation."
For most of the twentieth century, El Niño was considered a large local phenomenon.
The Great El Niño of 1982-83 led to a sharp rise in the interest of the scientific community in this phenomenon.
History of the phenomenon
ENSO conditions have occurred every 2 to 7 years for at least the last 300 years, but most of them have been weak.
Major ENSO events occurred in 1790–93, 1828, 1876–78, 1891, 1925–26, 1982–83, and 1997–98.
The most recent El Niño events occurred in 1986-1987, 1991-1992, 1993, 1994, 1997-1998 and 2002-2003.
The 1997–1998 El Niño in particular was strong and brought international attention to the phenomenon, while what was unusual about the 1990–1994 period was that El Niño occurred very frequently (but mostly weakly).
El Niño in the history of civilization
The mysterious disappearance of the Mayan civilization in Central America could be caused by severe climate changes. This conclusion was reached by a group of researchers from the German National Center for Geosciences, writes the British newspaper The Times.Scientists tried to establish why, at the turn of the 9th and 10th centuries AD, at opposite ends of the earth, the two largest civilizations of that time ceased to exist almost simultaneously. We are talking about the Mayans and the fall of the Chinese Tang Dynasty, which was followed by a period of internecine strife.
Both civilizations were located in monsoon regions, the moisture of which depends on seasonal precipitation. However, at this time, apparently, the rainy season was not able to provide enough moisture for the development of agriculture.
The ensuing drought and subsequent famine led to the decline of these civilizations, researchers believe. They link climate change to the natural phenomenon El Niño, which refers to temperature fluctuations in the surface waters of the eastern Pacific Ocean in tropical latitudes. This leads to large-scale disturbances in atmospheric circulation, causing droughts in traditionally wet regions and floods in dry ones.
Scientists came to these conclusions by studying the nature of sedimentary deposits in China and Mesoamerica dating back to this period. The last emperor of the Tang Dynasty died in 907 AD, and the last known Mayan calendar dates back to 903.
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General idea El Niño is a fluctuation in the temperature of the surface layer of water in the equatorial Pacific Ocean, which has a noticeable effect on the climate. In a narrower sense, El Niño is a phase of the Southern Oscillation in which an area of heated surface water moves eastward. At the same time, trade winds weaken or stop altogether, and upwelling slows down in the eastern part of the Pacific Ocean, off the coast of Peru. The opposite phase of the oscillation is called La Niña.
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First signs of El Niño Increase in air pressure over the Indian Ocean, Indonesia and Australia. Drop in pressure over Tahiti, over the central and eastern parts of the Pacific Ocean. Weakening of trade winds in the South Pacific until they stop and the wind changes direction to the west. Warm air mass in Peru, rains in the Peruvian deserts. This is also the influence of El Nino
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The influence of El Niño on the climate of various regions In South America, the El Niño effect is most pronounced. This phenomenon typically causes warm and very humid summer periods (December to February) along the northern coast of Peru and Ecuador. When El Niño is strong, it causes severe flooding. Southern Brazil and northern Argentina also experience wetter than normal periods, but mostly in the spring and early summer. Central Chile experiences mild winters with plenty of rain, while Peru and Bolivia occasionally experience unusual winter snowfalls for the region.
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Losses and losses More than 15 years ago, when El Niño first showed its character, meteorologists had not yet connected the events of those years: droughts in India, fires in South Africa and hurricanes that swept through Hawaii and Tahiti. Later, when the reasons for these disturbances in nature became clear, the losses brought by the willfulness of the elements were calculated. But it turned out that this is not all. Let's say rains and floods are direct consequences of a natural disaster. But after them came secondary ones - for example, mosquitoes multiplied in new swamps and brought an epidemic of malaria to Colombia, Peru, India, and Sri Lanka. In Montana, people are being bitten by venomous snakes. They approached populated areas, chasing their prey - mice, and they left their settled places due to lack of water and came closer to people and to water.
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From myths to reality Meteorologists' predictions have been confirmed: catastrophic events associated with the El Niño current are hitting the earth one after another. Of course, it is very sad that all this is happening now. But still, it should be noted that for the first time humanity is encountering a global natural disaster, knowing its causes and the course of further development. The El Niño phenomenon is already quite well studied. Science has solved the mystery that plagued Peruvian fishermen. They did not understand why sometimes during the Christmas period the ocean becomes warmer and the shoals of sardines off the coast of Peru disappear. Because the arrival of warm water coincided with Christmas, the current was called El Niño, which means “baby boy” in Spanish. Fishermen, of course, are interested in the immediate reason for the departure of the sardines...
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The fish leave... ...The fact is that sardines feed on phytoplankton. And algae need sunlight and nutrients - primarily nitrogen and phosphorus. They are present in ocean water, and their supply in the upper layer is constantly replenished by vertical currents going from the bottom to the surface. But when the El Niño current turns back towards South America, its warm waters “lock” the exit of deep waters. Biogenic elements do not rise to the surface, and algae reproduction stops. The fish leave these places - they do not have enough food.
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Magellan's mistake The first European to swim across the largest ocean on the planet was Magellan. He called him "The Quiet One". As it soon became clear, Magellan was mistaken. It is in this ocean that most typhoons are born, and it produces three-quarters of the planet's clouds. Now we have also learned that the El Niño current emerging in the Pacific Ocean sometimes causes many different troubles and disasters on the planet...
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El Niño is an elongated tongue of highly heated water. It is equal in area to the United States. Heated water evaporates more intensely and “pumps” the atmosphere with energy faster. El Niño supplies it with 450 million megawatts, which is equivalent to the power of 300,000 large nuclear power plants. It is clear that this energy, according to the law of conservation of energy, does not disappear. And now in Indonesia, disaster broke out in full force. First, there was a raging drought on the island of Sumatra, then the dried-out forests began to burn. In the impenetrable smoke that enveloped the entire island, the plane crashed upon landing, and a tanker and a cargo ship collided at sea. The smoke reached Singapore and Malaysia...
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Years in which El Niño was recorded 1864, 1871, 1877-1878, 1884, 1891, 1899, 1911-1912, 1925-1926, 1939-1941, 1957-1958, 1965-1966, 1972, 1976, 82-1983 , 1986-1987, 1992-1993, 1997-1998. , in 1790-1793, 1828, 1876-1878, 1891, 1925-1926, 1982-1983 and 1997-1998, powerful phases of El Niño were recorded, while, for example, in 1991-1992, 1993, 1994 this phenomenon often repeating, it was weakly expressed. El Niño 1997-1998 was so strong that it attracted the attention of the world community and the press.
Rains, landslides, floods, drought, smog, monsoon rains, countless casualties, multi-billion dollar damage... The name of the destroyer is known: in melodic Spanish it sounds almost tender - El Niño (baby, little boy). This is what Peruvian fishermen call the warm current that appears off the coast of South America during the Christmas season, increasing the catch. True, sometimes instead of the long-awaited warming, a sharp cooling suddenly occurs. And then the current is called La Niña (girl).
The first mention of the term “El Niño” dates back to 1892, when Captain Camilo Carrilo made a report about this warm northern current at the Congress of the Geographical Society in Lima. The name "El Niño" is given to the current because it is most noticeable during the Christmas period. However, even then the phenomenon was interesting only because of its biological impact on the efficiency of the fertilizer industry.
For most of the twentieth century, El Niño was considered a large, but still local phenomenon.
The Great El Niño of 1982-1983 led to a sharp rise in the interest of the scientific community in this phenomenon.
The 1997-1998 El Niño far exceeded the one in 1982 in the number of deaths and destruction it caused and was the most violent of the last century. The disaster was so strong that at least 4,000 people died. Global damage was estimated at more than $20 billion.
In recent years, the press and media have contained many alarming reports about weather anomalies that have affected almost all continents of the Earth. At the same time, the unpredictable El Niño phenomenon, which brings heat to the eastern part of the Pacific Ocean, was called the main culprit of all climatic and social troubles. Moreover, some scientists viewed this phenomenon as a harbinger of even more radical climate change.
What data does science currently have about the mysterious El Niño current?
The El Niño phenomenon consists of a sharp increase in temperature (by 5-9 °C) of the surface layer of water in the eastern Pacific Ocean (in the tropical and central parts) over an area of about 10 million square meters. km.
The processes of formation of the strongest warm current in the ocean in our century presumably look as follows. Under normal weather conditions, when the El Niño phase has not yet set in, warm surface waters of the ocean are transported and retained by easterly winds - trade winds in the western zone of the tropical Pacific Ocean, where the so-called tropical warm pool (TTB) is formed. The depth of this warm layer of water reaches 100-200 meters. The formation of such a huge heat reservoir is the main necessary condition for the transition to the El Niño regime. Moreover, as a result of the surge of water, the ocean level off the coast of Indonesia is half a meter higher than the coast of South America. At the same time, the water surface temperature in the west in the tropical zone averages 29-30 °C, and in the east 22-24 °C. A slight cooling of the surface in the east is the result of upwelling, i.e., the rise of deep cold waters to the surface of the ocean when water is sucked in by trade winds. At the same time, the largest region of heat and stationary unstable equilibrium in the ocean-atmosphere system is formed above the TTB in the atmosphere (when all forces are balanced and the TTB is motionless).
For still unknown reasons, at intervals of 3-7 years, the trade winds weaken, the balance is upset, and the warm waters of the western basin rush east, creating one of the strongest warm currents in the World Ocean. Over a vast area in the eastern Pacific Ocean, there is a sharp increase in the temperature of the surface layer of the ocean. This is the onset of the El Niño phase. Its beginning is marked by a long onslaught of squally westerly winds. They replace the usual weak trade winds over the warm western part of the Pacific Ocean and prevent cold deep waters from rising to the surface. As a result, upwelling is blocked.
Although the processes themselves that develop during the El Niño phase are regional, their consequences are nonetheless global. El Niño is usually accompanied by environmental disasters: droughts, fires, heavy rains, causing flooding of vast areas of densely populated areas, which leads to the death of people and the destruction of livestock and crops in different regions of the Earth. El Niño has a significant impact on the global economy. According to American experts, in 1982-1983, economic damage from the consequences of El Niño amounted to $13 billion, and according to estimates from the world's leading insurance company Munich Re, damage from natural disasters in the first half of 1998 is estimated at $24 billion.
The warm western basin usually enters an opposite phase a year after an El Niño, when the eastern Pacific cools. Phases of warming and cooling alternate with a normal state, when heat accumulates in the western basin (WBT) and the state of stationary unstable equilibrium is restored.
According to many experts, the main cause of the ongoing cataclysms is global warming as a result of the “greenhouse effect” due to the technogenic development of the Earth and the accumulation of greenhouse gases in the atmosphere (water vapor, carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons).
Meteorological data on the temperature of the surface layer of the atmosphere, collected over the past hundred years, show that the climate on Earth has warmed by 0.5-0.6 °C. The steady rise in temperature was disrupted by a brief cold snap between 1940 and 1970, after which warming resumed.
Although the increase in temperature is consistent with the greenhouse effect hypothesis, there are other factors that influence warming (volcanic eruptions, ocean currents, etc.). It will be possible to establish the unambiguous cause of warming after the receipt of new data in the next 10-15 years. All models predict that warming will increase significantly in the coming decades. From this we can conclude that the frequency of the El Niño phenomenon and its intensity will increase.
Climate variations over the period of 3-7 years are determined by changes in vertical circulation in the ocean and atmosphere and ocean surface temperature. In other words, they change the intensity of heat and mass transfer between the ocean and the atmosphere. The ocean and atmosphere are open, nonequilibrium, nonlinear systems, between which there is a constant exchange of heat and moisture.
By the way, such systems are characterized by the self-organization of such formidable structures as tropical cyclones, which transport energy and moisture received from the ocean over long distances.
An assessment of the energy interaction between the ocean and the atmosphere allows us to come to the conclusion that the energy of El Niño can lead to disturbances in the entire atmosphere of the Earth, which leads to environmental disasters that have occurred in recent years.
In the future, as the famous Canadian scientist and climate change specialist Henry Hincheveld showed, “society needs to abandon the idea that climate is something unchanging. It is fluid, change will continue, and humanity needs to develop an infrastructure that allows it to be prepared to face the unexpected.”