El Niño
Southern Oscillation And El Niño(Spanish) El Niño- Baby, Boy) is a global ocean-atmospheric phenomenon. Being a characteristic feature of the Pacific Ocean, El Niño and La Niña(Spanish) La Nina- Baby, Girl) represent temperature fluctuations of surface waters in the tropics of the eastern Pacific Ocean. The names for these phenomena, borrowed from the native Spanish and first coined in 1923 by Gilbert Thomas Walker, 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 Walker 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.
El Niño and La Niña
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:
- 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.
The warm El Niño current, composed of plankton-poor tropical water and heated by its easterly 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.
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.
Extensive influence of El Niño conditions
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 coasts 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.
The direct effects of El Niño are reducing humidity in Indonesia, increasing the likelihood of wildfires, 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 Volcker circulations over South America.
Non-climatic effects
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 abundant 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 Mochico Indian 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.
History of the theory
The first mention of the term "El Niño" dates back to the year 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 (Peru 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. An association with flooding was reported in 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 that droughts in India and Australia occur at the same time. Norman Lockyer pointed out the same thing in Gilbert Volcker who first coined the term "Southern Oscillation".
For most of the twentieth century, El Niño was considered a large local phenomenon.
History of the phenomenon
ENSO conditions have occurred every 2-7 years for at least the last 300 years, but most of them have been weak.
Large ENSO events occurred in - , , - , , - , - and - 1998 .
The last El Niño events occurred in -, -, , , 1997-1998 and -2003.
The 1997-1998 El Niño in particular was strong and brought international attention to the phenomenon, while the 1997-1998 El Niño was unusual in that El Niño occurred very frequently (but mostly weakly).
El Niño in the history of civilization
Scientists tried to establish why, at the turn of the 10th century AD, the two largest civilizations of that time ceased to exist almost simultaneously on opposite ends of the earth. We are talking about the Mayan Indians 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.
Links
- The El Nino Theme Page Explains El Nino and La Nina, provides real time data, forecasts, animations, FAQ, impacts and more.
- The International Meteorological Organization announced the detection of the beginning of the event La Niña in the Pacific Ocean. (Reuters/YahooNews)
Literature
- Cesar N. Caviedes, 2001. El Niño in History: Storming Through the Ages(University Press of Florida)
- Brian Fagan, 1999. Floods, Famines, and Emperors: El Niño and the Fate of Civilizations(Basic Books)
- Michael H. Glantz, 2001. Currents of change, ISBN 0-521-78672-X
- Mike Davis Late Victorian Holocausts: El Niño Famines and the Making of the Third World(2001), ISBN 1-85984-739-0
| Climate, Climatology | |
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| Changing of the climate | Paleoclimatology El Niño Geochemical carbon cycle Proterozoic glaciation, Ice Age, Little Ice Age Thermal maximum ( |
The first time I heard the word “El Niño” was in the United States in 1998. At that time, this natural phenomenon was well known to Americans, but almost unknown in our country. And it’s not surprising, because El Niño originates in the Pacific Ocean off the coast of South America and greatly influences the weather in the southern states of the United States. El Niño(translated from Spanish El Niño- baby, boy) in the terminology of climatologists - one of the phases of the so-called Southern Oscillation, i.e. fluctuations in the temperature of the surface layer of water in the equatorial Pacific Ocean, during which the area of heated surface water shifts to the east. (For reference: the opposite phase of oscillation - the displacement of surface waters to the west - is called La Niña (La Nina- baby, girl)). The El Niño phenomenon, which occurs periodically in the ocean, greatly affects the climate of the entire planet. One of the largest El Niño events occurred in 1997-1998. It was so strong that it attracted the attention of the world community and the press. At the same time, theories about the connection of the Southern Oscillation with global climate change spread. According to experts, the warming phenomenon El Niño is one of the main driving forces of natural variability in our climate.
In 2015 The World Meteorological Organization said the premature El Niño, dubbed the “Bruce Lee,” could be one of the strongest since 1950. Its appearance was expected last year, based on data on rising air temperatures, but these models did not materialize, and El Niño did not manifest itself.
In early November, the American agency NOAA (National Oceanic and Atmospheric Administration) released a detailed report on the state of the Southern Oscillation and analyzed the possible development of El Niño in 2015-2016. The report is published on the NOAA website. The conclusions of this document state that the conditions for the formation of El Niño are currently in place, and the average surface temperature of the equatorial Pacific (SST) is elevated and continues to rise. The probability that El Niño will develop throughout the winter of 2015-2016 is 95% . A gradual decline of El Niño is predicted in the spring of 2016. The report published an interesting graph showing the change in SST since 1951. Blue areas correspond to low temperatures (La Niña), orange indicates high temperatures (El Niño). The previous strong increase in SST of 2°C was observed in 1998.
Data obtained in October 2015 indicate that the SST anomaly at the epicenter already reaches 3 °C.
Although the causes of El Niño are not yet fully understood, it is known that it begins with trade winds weakening over several months. A series of waves move across the Pacific Ocean along the equator and create a body of warm water off South America, where the ocean normally has low temperatures due to the rise of deep ocean waters to the surface. Weakening trade winds coupled with strong westerly winds could also create a pair of cyclones (south and north of the equator), which is another sign of a future El Niño.
While studying the causes of El Niño, geologists noticed that the phenomenon occurs in the eastern part of the Pacific Ocean, where a powerful rift system has formed. American researcher D. Walker found a clear connection between increased seismicity on the East Pacific Rise and El Niño. Russian scientist G. Kochemasov saw another curious detail: the relief fields of ocean warming almost one to one repeat the structure of the earth's core.
One of the interesting versions belongs to the Russian scientist - Doctor of Geological and Mineralogical Sciences Vladimir Syvorotkin. It was first expressed back in 1998. According to the scientist, powerful centers of hydrogen-methane degassing are located in hot spots of the ocean. Or simply - sources of constant release of gases from the bottom. Their visible signs are thermal water outlets, black and white smokers. In the area of the coast of Peru and Chile, during El Niño years there is a massive release of hydrogen sulfide. The water is boiling and there is a terrible smell. At the same time, an amazing power is pumped into the atmosphere: approximately 450 million megawatts.
The El Niño phenomenon is now being studied and discussed more and more intensively. A team of researchers from the German National Center for Geosciences has concluded that the mysterious disappearance of the Mayan civilization in Central America may have been caused by strong climate changes caused by El Niño. At the turn of the 9th and 10th centuries AD, the two largest civilizations of that time ceased to exist on opposite ends of the earth almost simultaneously. We are talking about the Mayan Indians 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, a time came when the rainy season was unable to provide sufficient moisture for the development of agriculture. The drought and subsequent famine led to the decline of these civilizations, researchers believe. 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.
Climatologists and meteorologists say that El Niño2015, which will peak between November 2015 and January 2016, will be one of the strongest. El Niño will lead to large-scale disturbances in atmospheric circulation, which could cause droughts in traditionally wet regions and floods in dry ones.
A phenomenal phenomenon, which is considered one of the manifestations of the developing El Niño, is now observed in South America. The Atacama Desert, which is located in Chile and is one of the driest places on Earth, is covered with flowers.
This desert is rich in deposits of nitrate, iodine, table salt and copper; for four centuries there has been no significant precipitation. The reason is that the Peruvian Current cools the lower layers of the atmosphere and creates a temperature inversion that prevents precipitation. Rain falls here once every few decades. However, in 2015, the Atacama was hit by unusually heavy rainfall. As a result, dormant bulbs and rhizomes (horizontally growing underground roots) sprouted. The faded plains of the Atacama were covered with yellow, red, violet and white flowers - nolans, beaumaries, rhodophials, fuchsias and hollyhocks. The desert first bloomed in March, after unexpectedly intense rains caused flooding in the Atacama and killed about 40 people. Now the plants have bloomed for the second time in a year, before the start of the southern summer.
What will El Niño 2015 bring? A powerful El Niño is expected to bring welcome rainfall to dry areas of the United States. In other countries, its effect may be the opposite. In the western Pacific Ocean, El Niño creates high atmospheric pressure, bringing dry and sunny weather to large areas of Australia, Indonesia, and sometimes even India. The impact of El Niño on Russia has so far been limited. It is believed that under the influence of El Niño in October 1997, temperatures in Western Siberia reached above 20 degrees, and then they started talking about the retreat of permafrost to the north. In August 2000, Emergencies Ministry specialists attributed the series of hurricanes and rainstorms that swept across the country to the impact of the El Niño phenomenon.
At all times, the yellow press has increased its ratings due to various news of a mystical, catastrophic, provocative or revealing nature. However, recently, more and more people are beginning to be frightened by various natural disasters, the ends of the world, etc. In this article we will talk about one natural phenomenon that sometimes borders on mysticism - the warm El Niño current. What is this? This question is often asked by people on various Internet forums. Let's try to answer it.
Natural phenomenon El Niño
In 1997-1998 One of the largest natural disasters associated with this phenomenon in the entire history of observations took place on our planet. This mysterious phenomenon caused a lot of noise and attracted close attention from the world media, and the encyclopedia will tell you its name for the phenomenon. In scientific terms, El Niño is a complex of changes in the chemical and thermobaric parameters of the atmosphere and ocean that take on the character of a natural disaster. As you can see, this is a very difficult definition to understand, so let’s try to look at it through the eyes of an ordinary person. The reference literature says that El Niño is just a warm current that sometimes occurs off the coast of Peru, Ecuador and Chile. Scientists cannot explain the nature of the appearance of this current. The name of the phenomenon itself comes from the Spanish language and means “baby.” El Niño got its name due to the fact that it appears only at the end of December and coincides with Catholic Christmas.
Normal situation
In order to understand the anomalous nature of this phenomenon, let us first consider the usual climate situation in this region of the planet. Everyone knows that the mild weather in Western Europe is determined by the warm Gulf Stream, while in the Pacific Ocean of the Southern Hemisphere the tone is set by the cold Antarctic. The prevailing Atlantic winds here - the trade winds, which blow on the western South American coast, crossing the high Andes, leave all the moisture on the eastern slopes. As a result, the western part of the mainland is a rocky desert where rainfall is extremely rare. However, when the trade winds pick up so much moisture that they can transport it across the Andes, they form a powerful surface current here, which causes a surge of water off the coast. The attention of specialists was attracted by the colossal biological activity of this region. Here, in a relatively small area, annual fish production exceeds the global total by 20%. This also leads to an increase in fish-eating birds in the region. And in places where they accumulate, a colossal mass of guano (dung) - a valuable fertilizer - is concentrated. In some places the thickness of its layers reaches 100 meters. These deposits became the object of industrial production and export.
Catastrophe
Now let's look at what happens when the warm El Niño current appears. In this case, the situation changes dramatically. An increase in temperature leads to mass death or loss of fish and, as a result, birds. Next, there is a drop in atmospheric pressure in the eastern part of the Pacific Ocean, clouds appear, trade winds subside, and the winds change their direction to the opposite. As a result, torrents of water fall on the western slopes of the Andes, floods, floods, and mudslides rage here. And on the opposite side of the Pacific Ocean - in Indonesia, Australia, New Guinea - a terrible drought begins, which leads to forest fires and the destruction of agricultural crops. However, the El Niño phenomenon is not limited to this: “red tides”, which are caused by the growth of microscopic algae, begin to develop from the Chilean coast to California. It would seem that everything is clear, but the nature of the phenomenon is not completely clear. Thus, oceanographers consider the appearance of warm waters to be a consequence of a change in winds, and meteorologists explain the change in winds by the heating of waters. What kind of vicious circle is this? However, let's look at some things that climate scientists have missed.
Degassing El Niño scenario
What kind of phenomenon this is, geologists helped to figure it out. For ease of understanding, we will try to move away from specific scientific terms and tell everything in a generally accessible language. It turns out that El Niño forms in the ocean above one of the most active geological areas of the rift system (a rupture in the earth's crust). Hydrogen is actively released from the depths of the planet, which, upon reaching the surface, forms a reaction with oxygen. As a result, heat arises, which warms the water. In addition, this also leads to the appearance of over the region, which also contributes to more intense heating of the ocean by solar radiation. Most likely, the role of the Sun is decisive in this process. All this leads to an increase in evaporation, a decrease in pressure, as a result of which a cyclone is formed.
Biological productivity
Why is there such high biological activity in this region? Scientists estimate that it corresponds to the heavily fertilized ponds in Asia and is more than 50 times higher than in other parts of the Pacific Ocean. Traditionally, this is usually explained by the wind driving warm waters from the coast - upwelling. As a result of this process, cold water, enriched with nutrients (nitrogen and phosphorus), rises from the depths. And when El Niño appears, upwelling is interrupted, as a result of which birds and fish die or migrate. It would seem that everything is clear and logical. However, here too, scientists do not say much. For example, the mechanism for rising water from the depths of the ocean slightly Scientists measure temperatures at various depths oriented perpendicular to the shore. Then graphs (isotherms) are constructed, comparing the level of coastal and deep waters, and the above-mentioned conclusions are drawn from this. However, measuring the temperature in coastal waters is incorrect, because it is known that their coldness is determined by the Peruvian Current. And the process of constructing isotherms across the coastline is incorrect, because the prevailing winds blow along it.
But the geological version easily fits into this scheme. It has long been known that the water column of this region has a very low oxygen content (the reason is a geological discontinuity) - lower than anywhere on the planet. And the upper layers (30 m), on the contrary, are abnormally rich in it due to the Peruvian Current. It is in this layer (above the rift zones) that unique conditions for the development of life are created. When the El Niño current appears, degassing in the region increases, and the thin surface layer is saturated with methane and hydrogen. This leads to the death of living beings, and not at all the lack of food supply.
Red tides
However, with the onset of an environmental disaster, life here does not stop. Single-celled algae - dinoflagellates - begin to actively reproduce in the water. Their red color is protection from solar ultraviolet radiation (we already mentioned that an ozone hole forms over the region). Thus, thanks to the abundance of microscopic algae, many marine organisms that act as ocean filters (oysters, etc.) become poisonous, and eating them leads to severe poisoning.
The model is confirmed
Let's consider an interesting fact that confirms the reality of the degassing version. American researcher D. Walker carried out work to analyze sections of this underwater ridge, as a result of which he came to the conclusion that during the years of El Niño, seismic activity sharply increased. But it has long been known that it is often accompanied by increased degassing of the subsoil. So, most likely, scientists simply confused cause and effect. It turns out that the changed direction of El Niño is a consequence, not the cause of subsequent events. This model is also supported by the fact that during these years the water literally boils with the release of gases.
La Niña
This is the name given to the final phase of El Niño, which results in a sharp cooling of the water. A natural explanation for this phenomenon is the destruction of the ozone layer over Antarctica and the Equator, which causes and leads to an influx of cold water in the Peruvian Current, which cools El Niño.
Root cause in space
The media blame El Niño for floods in South Korea, unprecedented frosts in Europe, droughts and fires in Indonesia, destruction of the ozone layer, etc. However, if we remember the fact that the mentioned current is just a consequence of geological processes occurring in the bowels of the Earth, then we should think about the root cause. And it is hidden in the influence on the core of the planet of the Moon, the Sun, the planets of our system, as well as other celestial bodies. So it’s useless to blame El Niño...
The natural phenomenon El Niño, which took place in 1997-1998, had no equal in scale in the entire history of observations. What is this mysterious phenomenon that has caused so much noise and attracted close attention from the media?
In scientific terms, El Niño is a complex of interdependent changes in thermobaric and chemical parameters of the ocean and atmosphere, taking on the character of natural disasters. According to reference literature, it is a warm current that sometimes occurs for unknown reasons off the coast of Ecuador, Peru and Chile. Translated from Spanish, "El Niño" means "baby". Peruvian fishermen gave it this name because warming waters and associated mass fish kills usually occur at the end of December and coincide with Christmas. Our magazine already wrote about this phenomenon in No. 1 in 1993, but since that time researchers have accumulated a lot of new information.
NORMAL SITUATION
To understand the anomalous nature of the phenomenon, let us first consider the usual (standard) climate situation off the South American coast of the Pacific Ocean. It is quite peculiar and is determined by the Peruvian Current, which carries cold waters from Antarctica along the western coast of South America to the Galapagos Islands lying on the equator. Usually the trade winds blowing here from the Atlantic, crossing the high-mountain barrier of the Andes, leave moisture on their eastern slopes. And therefore the western coast of South America is a dry rocky desert, where rain is extremely rare - sometimes it does not fall for years. When the trade winds collect so much moisture that they carry it to the western shores of the Pacific Ocean, they form here the predominant westerly direction of surface currents, causing a surge of water off the coast. It is unloaded by the counter-trade Cromwell Current in the equatorial zone of the Pacific Ocean, which covers a 400-kilometer strip here and, at depths of 50-300 m, transports huge masses of water back to the east.
The attention of specialists is attracted by the colossal biological productivity of coastal Peruvian-Chilean waters. Here, in a small space, constituting a fraction of a percent of the entire water area of the World Ocean, the annual production of fish (mainly anchovy) exceeds 20% of the global total. Its abundance attracts huge flocks of fish-eating birds - cormorants, gannets, pelicans. And in areas where they accumulate, colossal masses of guano (bird droppings) - a valuable nitrogen-phosphorus fertilizer - are concentrated; its deposits, ranging in thickness from 50 to 100 m, became the object of industrial development and export.
CATASTROPHE
During El Niño years, the situation changes dramatically. First, the water temperature rises by several degrees and mass death or departure of fish from this water area begins, and as a result, birds disappear. Then, in the eastern part of the Pacific Ocean, atmospheric pressure drops, clouds appear above it, trade winds subside, and air flows over the entire equatorial zone of the ocean change direction. Now they are moving from west to east, carrying moisture from the Pacific region and dumping it on the Peruvian-Chilean coast.
Events are developing especially catastrophically at the foot of the Andes, which now block the path of the western winds and receive all their moisture onto their slopes. As a result, floods, mudflows, and floods are raging in a narrow strip of rocky coastal deserts on the western coast (at the same time, the territories of the Western Pacific region are suffering from terrible drought: tropical forests are burning in Indonesia and New Guinea, and agricultural yields are sharply falling in Australia). To top it all off, so-called “red tides” are developing from the Chilean coast to California, caused by the rapid growth of microscopic algae.
So, the chain of catastrophic events begins with a noticeable warming of surface waters in the eastern Pacific Ocean, which has recently been successfully used to predict El Niño. A network of buoy stations has been installed in this water area; with their help, the temperature of ocean water is constantly measured, and the data obtained is promptly transmitted via satellites to research centers. As a result, it was possible to warn in advance about the onset of the most powerful El Niño known to date - in 1997-98.
At the same time, the reason for the heating of ocean water, and therefore the occurrence of El Niño itself, is still not completely clear. Oceanographers explain the appearance of warm water south of the equator by a change in the direction of the prevailing winds, while meteorologists consider the change in winds to be a consequence of heating the water. Thus, a kind of vicious circle is created.
To get closer to understanding the genesis of El Niño, let us pay attention to a number of circumstances that are usually overlooked by climate specialists.
EL NINO DEGASION SCENARIO
For geologists, the following fact is absolutely obvious: El Niño develops over one of the most geologically active areas of the world rift system - the East Pacific Rise, where the maximum spreading rate (spreading of the ocean floor) reaches 12-15 cm/year. In the axial zone of this underwater ridge, a very high heat flow from the bowels of the earth is noted, manifestations of modern basaltic volcanism are known here, thermal water outlets and traces of the intensive process of modern ore formation in the form of numerous black and white “smokers” were discovered.
In the water area between 20 and 35 south. w. Nine hydrogen jets were recorded at the bottom - the release of this gas from the bowels of the earth. In 1994, an international expedition discovered the world's most powerful hydrothermal system here. In its gas emanations, the 3 He/4 He isotope ratios turned out to be abnormally high, which means that the source of degassing is located at great depths.
A similar situation is typical for other “hot spots” on the planet - Iceland, Hawaii, and the Red Sea. There, at the bottom there are powerful centers of hydrogen-methane degassing and above them, most often in the Northern Hemisphere, the ozone layer is destroyed
, which gives grounds to apply the model I created for the destruction of the ozone layer by hydrogen and methane flows to El Niño.
This is roughly how this process begins and develops. Hydrogen, released from the ocean floor from the rift valley of the East Pacific Rise (its sources were instrumentally discovered there) and reaching the surface, reacts with oxygen. As a result, heat is generated, which begins to warm up the water. The conditions here are very favorable for oxidative reactions: the surface layer of water is enriched with oxygen during wave interaction with the atmosphere.
However, the question arises: can hydrogen coming from the bottom reach the ocean surface in noticeable quantities? A positive answer was given by the results of American researchers who discovered twice the content of this gas in the air over the Gulf of California, compared to the background level. But here at the bottom there are hydrogen-methane sources with a total flow rate of 1.6 x 10 8 m 3 /year.
Hydrogen, rising from the depths of water into the stratosphere, forms an ozone hole into which ultraviolet and infrared solar radiation “falls”. Falling onto the surface of the ocean, it intensifies the heating of its upper layer that has begun (due to the oxidation of hydrogen). Most likely, it is the additional energy of the Sun that is the main and determining factor in this process. The role of oxidative reactions in heating is more problematic. This could not be discussed if it were not for the significant (from 36 to 32.7% o) desalination of ocean water that occurs simultaneously with it. The latter is probably accomplished by the very addition of water that is formed during the oxidation of hydrogen.
Due to the heating of the surface layer of the ocean, the solubility of CO 2 in it decreases, and it is released into the atmosphere. For example, during the El Niño of 1982-83. An additional 6 billion tons of carbon dioxide entered the air. Water evaporation also increases, and clouds appear over the eastern Pacific Ocean. Both water vapor and CO 2 are greenhouse gases; they absorb thermal radiation and become an excellent accumulator of additional energy coming through the ozone hole.
Gradually the process is gaining momentum. Anomalous heating of the air leads to a decrease in pressure, and a cyclonic region forms over the eastern part of the Pacific Ocean. It is this that breaks the standard trade wind pattern of atmospheric dynamics in the area and “sucks” air from the western part of the Pacific Ocean. Following the subsidence of the trade winds, the surge of water off the Peruvian-Chilean coast decreases and the equatorial Cromwell countercurrent ceases to operate. Strong heating of the water leads to the formation of typhoons, which is very rare in normal years (due to the cooling influence of the Peruvian Current). From 1980 to 1989, ten typhoons occurred here, seven of them in 1982-83, when El Niño raged.
BIOLOGICAL PRODUCTIVITY
Why is biological productivity so high off the west coast of South America? According to experts, it is the same as in the abundantly “fertilized” fish ponds of Asia, and 50 thousand times higher (!) than in other parts of the Pacific Ocean, if calculated by the number of fish caught. Traditionally, this phenomenon is explained by upwelling - a wind-driven movement of warm water from the shore, forcing cold water enriched with nutritional components, mainly nitrogen and phosphorus, to rise from the depths. During El Niño years, when the wind changes direction, upwelling is interrupted, and therefore, the flow of nutrient water stops. As a result, fish and birds die or migrate due to starvation.
All this resembles a perpetual motion machine: the abundance of life in surface waters is explained by the supply of nutrients from below, and their excess below is explained by the abundance of life above, because dying organic matter settles to the bottom. However, what is primary here, what gives impetus to such a cycle? Why does it not dry up, although, judging by the power of the guano deposits, it has been active for millennia?
The mechanism of wind upwelling itself is not very clear. The associated rise of deep water is usually determined by measuring its temperature on profiles of different levels oriented perpendicular to the coastline. Isotherms are then constructed that show the same low temperatures near the coast and at great depths away from it. And in the end they conclude that cold waters are rising. But it is known: the low temperature near the coast is caused by the Peruvian Current, so the described method for determining the rise of deep waters is hardly correct. Finally, another ambiguity: the profiles mentioned are built across the coastline, and the prevailing winds here blow along it.
I am by no means going to overthrow the concept of wind upwelling - it is based on an understandable physical phenomenon and has a right to life. However, upon closer acquaintance with it in this area of the ocean, all of the listed problems inevitably arise. Therefore, I propose a different explanation for the anomalous biological productivity off the western coast of South America: it is again determined by the degassing of the earth’s interior.
In fact, not the entire Peruvian-Chilean coastal strip is equally productive, as it should be under the influence of climatic upwelling. There are two separate “spots” here - northern and southern, and their position is controlled by tectonic factors. The first is located above a powerful fault extending from the ocean to the continent south of the Mendana fault (6-8 o S) and parallel to it. The second spot, somewhat smaller in size, is located just north of the Nazca Ridge (13-14 S latitude). All of these oblique (diagonal) geological structures running from the East Pacific Rise towards South America are essentially degassing zones; through them, a huge number of different chemical compounds flow from the earth’s interior to the bottom and into the water column. Among them there are, of course, vital elements - nitrogen, phosphorus, manganese, and plenty of microelements. In the thickness of the coastal Peruvian-Ecuadorian waters, the oxygen content is the lowest in the entire World Ocean, since the main volume here is made up of reduced gases - methane, hydrogen sulfide, hydrogen, ammonia. But the thin surface layer (20-30 m) is abnormally rich in oxygen due to the low temperature of the water brought here from Antarctica by the Peruvian Current. In this layer above fault zones - sources of endogenous nutrients - unique conditions for the development of life are created.
However, there is an area in the World Ocean that is not inferior in bioproductivity to the Peruvian one, and perhaps even superior to it - off the western coast of South Africa. It is also considered a wind upwelling zone. But the position of the most productive area here (Walvis Bay) is again controlled by tectonic factors: it is located above a powerful fault zone running from the Atlantic Ocean to the African continent somewhat north of the South Tropic. And the cold, oxygen-rich Benguela Current runs along the coast from Antarctica.
The region of the Southern Kuril Islands, where the cold current passes over the submeridional marginal ocean fault Jonah, is also distinguished by its colossal fish productivity. At the height of the saury season, literally the entire Far Eastern fishing fleet of Russia gathers in a small water area of the South Kuril Strait. It is appropriate here to recall Kuril Lake in Southern Kamchatka, where one of the largest spawning grounds of sockeye salmon (a type of Far Eastern salmon) is located in our country. The reason for the very high biological productivity of the lake, according to experts, is the natural “fertilization” of its water with volcanic emanations (it is located between two volcanoes - Ilyinsky and Kambalny).
However, let's return to El Niño. During the period when degassing intensifies off the coast of South America, the thin, oxygenated and teeming with life surface layer of water is blown through with methane and hydrogen, oxygen disappears, and the mass death of all living things begins: from the bottom of the sea, trawls lift a huge number of bones of large fish, onto Seals are dying on the Galapagos Islands. However, it is unlikely that the fauna is dying due to a decrease in ocean bioproductivity, as the traditional version says. She is most likely poisoned by poisonous gases rising from the bottom. After all, death comes suddenly and overtakes the entire marine community - from phytoplankton to vertebrates. Only birds die from hunger, and even then mostly chicks - adults simply leave the danger zone.
"RED TIDES"
However, after the mass disappearance of the biota, the amazing riot of life off the western coast of South America does not stop. In oxygen-deprived waters blown with toxic gases, single-celled algae - dinoflagellates - begin to rapidly develop. This phenomenon is known as "red tide" and is so named because only intensely colored algae thrive in such conditions. Their color is a kind of protection from solar ultraviolet radiation, acquired back in the Proterozoic (over 2 billion years ago), when there was no ozone layer and the surface of reservoirs was subjected to intense ultraviolet irradiation. So during “red tides” the ocean seems to return to its “pre-oxygen” past. Due to the abundance of microscopic algae, some marine organisms that usually act as water filters, such as oysters, become poisonous at this time and their consumption can lead to severe poisoning.
Within the framework of the gas-geochemical model I developed for the anomalous bioproductivity of local areas of the ocean and the periodically rapid death of biota in it, other phenomena are also explained: the massive accumulation of fossil fauna in ancient shales of Germany or phosphorites of the Moscow region, overflowing with the remains of fish bones and cephalopod shells.
MODEL CONFIRMED
I will give some facts indicating the reality of the El Niño degassing scenario.
During the years of its manifestation, the seismic activity of the East Pacific Rise sharply increases - this was the conclusion made by the American researcher D. Walker, having analyzed the relevant observations from 1964 to 1992 in the area of this underwater ridge between 20 and 40 degrees. w. But, as has long been established, seismic events are often accompanied by increased degassing of the earth’s interior. The model I developed is also supported by the fact that the waters off the western coast of South America literally boil with the release of gases during El Niño years. The hulls of ships are covered with black spots (the phenomenon is called “El Pintor”, translated from Spanish as “the painter”), and the foul smell of hydrogen sulfide spreads over large areas.
In the African Gulf of Walvis Bay (mentioned above as an area of anomalous bioproductivity), environmental crises also periodically arise, following the same scenario as off the coast of South America. Emissions of gases begin in this bay, which leads to massive fish deaths, then “red tides” develop here, and the smell of hydrogen sulfide on land is felt even 40 miles from the coast. All this is traditionally associated with the abundant release of hydrogen sulfide, but its formation is explained by the decomposition of organic residues on the seabed. Although it is much more logical to consider hydrogen sulfide as a common component of deep emanations - after all, it comes out here only above the fault zone. The penetration of gas far onto land is also easier to explain by its arrival from the same fault, tracing from the ocean to the interior of the continent.
It is important to note the following: when deep gases enter ocean water, they are separated due to sharply different (by several orders of magnitude) solubility. For hydrogen and helium, it is 0.0181 and 0.0138 cm 3 in 1 cm 3 of water (at temperatures up to 20 C and a pressure of 0.1 MPa), and for hydrogen sulfide and ammonia it is incomparably greater: 2.6 and 700 cm, respectively 3 in 1 cm 3 . That is why the water above the degassing zones is greatly enriched with these gases.
A strong argument in favor of the El Niño degassing scenario is a map of the average monthly ozone deficiency over the equatorial region of the planet, compiled at the Central Aerological Observatory of the Hydrometeorological Center of Russia using satellite data. It clearly shows a powerful ozone anomaly over the axial part of the East Pacific Rise slightly south of the equator. I note that by the time the map was published, I had published a qualitative model explaining the possibility of destruction of the ozone layer above this zone. By the way, this is not the first time that my forecasts of the possible occurrence of ozone anomalies have been confirmed by field observations.
LA NINA
This is the name of the final phase of El Niño - a sharp cooling of water in the eastern part of the Pacific Ocean, when for a long period its temperature drops several degrees below normal. A natural explanation for this is the simultaneous destruction of the ozone layer both over the equator and over Antarctica. But if in the first case it causes heating of the water (El Niño), then in the second it causes a strong melting of ice in Antarctica. The latter increases the influx of cold water into the Antarctic waters. As a result, the temperature gradient between the equatorial and southern parts of the Pacific Ocean sharply increases, and this leads to an intensification of the cold Peruvian Current, which cools the equatorial waters after the weakening of degassing and restoration of the ozone layer.
THE RIGITAL CAUSE IS IN SPACE
First, I would like to say a few “justifying” words about El Niño. The media, to put it mildly, are not entirely right when they accuse him of causing disasters such as floods in South Korea or unprecedented frosts in Europe. After all, deep degassing can simultaneously increase in many areas of the planet, which leads there to the destruction of the ozonosphere and the appearance of anomalous natural phenomena, which have already been mentioned. For example, the heating of water that precedes the occurrence of El Niño occurs under ozone anomalies not only in the Pacific, but also in other oceans.
As for the intensification of deep degassing, it is determined, in my opinion, by cosmic factors, mainly by the gravitational effect on the liquid core of the Earth, where the main planetary reserves of hydrogen are contained. An important role in this case is probably played by the relative position of the planets and, first of all, interactions in the Earth - Moon - Sun system. G.I. Voitov and his colleagues from the Joint Institute of Physics of the Earth named after. O. Yu. Schmidt of the Russian Academy of Sciences established long ago: degassing of the subsoil noticeably increases during periods close to the full moon and new moon. It is also influenced by the position of the Earth in its circumsolar orbit and by changes in its rotation speed. The complex combination of all these external factors with processes in the depths of the planet (for example, the crystallization of its inner core) determines the pulses of increased planetary degassing, and hence the El Niño phenomenon. Its 2-7-year quasi-periodicity was revealed by domestic researcher N. S. Sidorenko (Hydrometeorological Center of Russia), having analyzed a continuous series of atmospheric pressure differences between the stations of Tahiti (on the island of the same name in the Pacific Ocean) and Darwin (northern coast of Australia) over a long period - since 1866 to the present time.
Candidate of Geological and Mineralogical Sciences V. L. SYVOROTKIN, Moscow State University. M. V. Lomonosova
The Southern Oscillation and El Niño are 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 Volker, 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 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 abundant 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 western 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 Mayan Indians 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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