Hydrology. La nina natural phenomenon el niño
Can you imagine such a picture in the underground passage of your city?
But in vain. Everything is possible in our life, and even more!
Temperatures are rising, the climate is changing, rivers are overflowing, the world's oceans are rising, and scammers are skimming the cream off people's fears. global warming And global example to that - the premiere of the film "". What is the connection with the cards, you think?
And here she is!
Recent sea level data from NASA (with the Jason-2 oceanography satellite) show that a large-scale, persistent weakening of the winds in the western and central equatorial Pacific during October caused a strong, eastward moving wave warm water. In the central and eastern equatorial Pacific, this warm wave manifests itself as an area of higher sea level compared to normal and warmer sea surface temperatures.
The image was created using data collected by a US/European satellite during a 10-day period spanning late October and early November. The picture shows a red and white area in the central and eastern equatorial Pacific Ocean, which is about 10 to 18 centimeters above normal. These areas contrast with the western equatorial Pacific, where lower water levels (blue and purple areas) are between 8 to 15 centimeters below normal. Along the equator, red and white represent areas where sea surface temperatures are one to two degrees Celsius above normal.
This is a set of interacting parts of one global system of ocean-atmospheric climatic fluctuations that occur as a sequence of oceanic and atmospheric circulations. This is the world's best-known source of interannual weather and climate variability (from 3 to 8 years).
The signs of El Niño are as follows:
Rising air pressure over the Indian Ocean, Indonesia and Australia.
Warm air appears next to Peru, causing rain in the deserts.
Warm water spreads from the western Pacific to the eastern. She brings rain with her, causing it in areas where it is usually dry.
As El Niño's warm waters feed storms, it creates increased rainfall in the east-central and eastern Pacific Oceans.
West of the Antarctic Peninsula, Ross Land, Bellingshausen and Amundsen Seas are covered big amount snow and ice during El Niño. The latter two and the Wedell Sea are getting warmer and under higher atmospheric pressure.
IN North America Winters are generally warmer than usual in the Midwest and Canada, while wetter in central and southern California, northwestern Mexico and the southeastern United States. The Pacific Northwest states, in other words, are drained during El Niño.
Based on these data, I can write new script for a crushing blockbuster. As usual: apocalypse, catastrophe, panic… El Niño 2029 or El Niño 2033. Now it is fashionable to invent everything with numbers. Or maybe just.
El Ninh oh-oh
Named after Volcker, the circulation is an essential aspect of the Pacific ENSO (El Nino Southern Oscillation) phenomenon. ENSO is a set of 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 El Niño warm events, as it warms up, it expands over much of the Pacific tropics and becomes in direct relation to the intensity of the SOI (Southern Oscillation Index). While ENSO events are mostly between the Pacific and Indian Oceans, ENSO events in the Atlantic Ocean lag behind the first by 12-18 months. Most of the countries that are subject to ENSO events are developing countries, with economies heavily dependent on the agricultural and fishing sectors. New opportunities to predict the onset of ENSO events in three oceans could have global socio-economic implications. Since ENSO is a global and natural part of the Earth's climate, it is important to find out if the change in intensity and frequency could be the result of global warming. Low frequency changes have already been detected. Inter-decadal ENSO modulations may also exist.
El Niño and La Niña
Common Pacific pattern. Equatorial winds collect a warm water basin towards the west. Cold waters rise to the surface along the South American coast.AND La Niña officially defined as long-term marine surface temperature anomalies greater than 0.5 °C across the Pacific Ocean in its central tropical region. When a +0.5 °C (-0.5 °C) condition is observed for up to five months, it is classified as an El Niño (La Niña) condition. If the anomaly persists for five months or longer, then 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.
Rising air pressure over the Indian Ocean, Indonesia and Australia.
Drop in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean.
The trade winds in the South Pacific are weakening or heading east.
Warm air appears next to Peru, causing rain in the deserts.
Warm water spreads from the western part of the Pacific Ocean to the east. She brings rain with her, causing it in areas where it is usually dry.
Warm El Niño current , consisting of plankton-poor tropical water and heated by its easterly branch in the Equatorial Current, replaces the cold, plankton-rich waters of the Humboldt Current, also known as the Peruvian Current, which contains large populations commercial fish. Most years, 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 foreign market.
The Volcker circulation is visible on the surface as easterly trade winds, which move westward water and air heated by the sun. It also creates oceanic upwelling off the coast of Peru and Ecuador and cold waters rich in plankton flow to the surface, increasing fish stocks. The western equatorial part of the Pacific Ocean is characterized by warm, humid weather and low atmospheric pressure. The accumulated moisture falls out 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, La Niña is characterized by unusually cold temperatures in the eastern equatorial region compared to El Niño, which in turn is characterized by unusually high temperature in the same region. Atlantic tropical cyclone activity in general case intensifies during La Niña. The La Niña condition often occurs after El Niño, especially when the latter is very strong.
Southern Oscillation Index (SOI)
The Southern Oscillation Index is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.Long-term negative SOI values often signal El Niño episodes. These negative values are usually associated with prolonged warming in the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific trade winds and a decrease in precipitation in the east and north of Australia.
Positive values SOIs are associated with strong Pacific trade winds and warming water temperatures in northern Australia, well known as the La Niña episode. The waters of the central and eastern tropical Pacific become colder during this time. Together, all of this increases the likelihood of more rainfall in eastern and northern Australia than usual.
El Niño influence
As El Niño's warm waters feed the storms, it creates an increase in rainfall in the east-central and eastern Pacific Oceans.In South America, the El Niño effect is more pronounced than in North America. El Niño is associated with warm and very wet summers (December-February) along the coasts of northern Peru and Ecuador, causing severe flooding whenever the event is strong. Effects during February, March, April can become critical. Southern Brazil and northern Argentina also experience wetter than normal conditions, but mostly during the spring and early summer. Central Region of Chile receives mild winter with a lot of rain, and the Peruvian-Bolivian Plateau sometimes experiences unusual winter snowfalls for this region. Dryer and warmer weather is observed in the Amazon Basin, Colombia and Central America.
Direct effects of El Niño lead to a decrease in 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 west of the Antarctic Peninsula, Ross Land, the Bellingshausen and Amundsen seas are covered with large amounts of snow and ice during El Niño. The latter two and the Wedell Sea are getting warmer and under higher atmospheric pressure.
In North America, winters tend to be warmer than usual in the Midwest and Canada, while it is getting wetter in central and southern California, northwestern Mexico, and the southeastern United States. The Pacific Northwest states, in other words, are drained during El Niño. Conversely, during La Niña, the US Midwest dries up. El Niño is also associated with a decrease in Atlantic hurricane activity.
Eastern Africa, including Kenya, Tanzania and the White Nile Basin, experience prolonged rains from March to May. Droughts haunt the southern and central regions of Africa from December to February, mainly Zambia, Zimbabwe, Mozambique and Botswana.
Warm Basin of the Western Hemisphere. A study of climate data showed that about half summer periods after El Niño there is an unusual warming of the Western Hemisphere Warm Basin. This affects the weather in the region and seems to be related to the North Atlantic Oscillation.
Atlantic effect. An El Niño-like effect is sometimes observed in the Atlantic Ocean, where the water along the African equatorial coast becomes warmer, while off the coast of Brazil it becomes colder. This can be attributed to the Walker circulations over South America.
Non-climatic effects of El Niño
Along east coast South America's El Niño reduces the upwelling of cold, plankton-rich water that supports large fish populations, which in turn support abundance sea birds whose droppings support the fertilizer industry.The local fishing industry along the coastline may be short of fish during long El Niño events. The largest global fish collapse due to overfishing, which occurred in 1972 during El Niño, led to a decrease in the population of Peruvian anchovies. During the events of 1982-83, populations of southern horse mackerel and anchovies decreased. Although the number of shells in warm water increased, but the hake went deeper into the cold water, and the shrimps and sardines went south. But the catch of some other fish species has been increased, for example, the common horse mackerel increased its population during warm events.
Changes in location and types of fish due to changing conditions have provided challenges for the fishing industry. The Peruvian sardine left due to El Nino to the Chilean coast. Other conditions have only led to further complications, such as the government of Chile in 1991 created restrictions on fishing.
It is postulated that El Niño led to the disappearance of the Mochico Indian tribe and other tribes of the pre-Columbian Peruvian culture.
Causes of El Niño
The mechanisms that can trigger El Niño events are still under investigation. It is difficult to find patterns that can show causes or allow predictions to be made.Bjerknes in 1969 suggested that the anomalous warming in the eastern Pacific could be attenuated by the east-west temperature difference, causing weakening in the Volcker circulation and the trade winds that move warm water westward. The result is an increase in warm water towards the east.
Wirtky 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. Nevertheless, no bulges were noticed on the eve of the events of 1982-83.
Rechargeable Oscillator: Some mechanisms have been proposed that when warm regions are created in the equatorial region they are dispersed to higher latitudes via 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, several weather conditions may have caused easterly wind anomalies. For example, a cyclone in the north and an anticyclone in the south create an east wind between them. Such patterns can interact with the westerly current across the Pacific Ocean and create a continued eastward trend. The weakening of the westerly current at this time may be the final trigger.
The Equatorial Pacific can lead to El Niño-like conditions with a few random variations in behavior. Weather patterns from outside or volcanic activity can be such factors.
The Madden-Julian Oscillation (MJO) is a major source of variability that can contribute to a more abrupt evolution leading to El Niño conditions through fluctuations in the winds blowing on low levels, and precipitation over the western and central parts of the 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 told a congress Geographical Society in Lima that the Peruvian sailors called the warm north current "El Niño", as it is most noticeable in the Christmas area. However, even then, the phenomenon was only interesting 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; upwelling of plankton 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 earth. The association with flooding was reported in 1895 by Pezet and Eguiguren.
Towards the end of the nineteenth century, interest arose in predicting climate anomalies (for food production) in India and Australia. Charles Todd in 1893 suggested that droughts in India and Australia occur at the same time. Norman Lockyer pointed out the same thing in 1904. In 1924, Gilbert Walker first coined the term "Southern Oscillation".
For most of the twentieth century, El Niño was considered a large local phenomenon.
The big El Niño in 1982-83 led to a sharp jump in interest scientific community to this phenomenon.
The history of the phenomenon
ENSO conditions have happened every 2-7 years for at least the last 300 years, but most have been mild.
Big 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 it was unusual for the 1990-1994 period that El Niño was very frequent (but mostly weak).
El Niño in the history of civilization
The mysterious disappearance of the Mayan civilization in Central America could be caused by strong climatic 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 almost simultaneously ceased to exist. It's about about the Maya Indians and the fall of the Chinese Tang Dynasty, followed by a period of internecine strife.
Both civilizations were located in monsoonal regions, the moistening of which depends on the seasonal precipitation. However, at the indicated time, apparently, the rainy season was not able to provide sufficient moisture for the development Agriculture.
The ensuing drought and subsequent famine led to the decline of these civilizations, the researchers believe. They link climate change to the natural phenomenon El Niño, which refers to temperature fluctuations surface waters of the eastern Pacific Ocean in tropical latitudes. This leads to large-scale disturbances in atmospheric circulation, which causes 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 related to the indicated period. The last emperor of the Tang Dynasty died in 907 AD, and the last known Mayan calendar dates back to 903.
Fires and floods, droughts and hurricanes all hit our Earth together in 1997. The fires turned the forests of Indonesia to ashes, then raged across the expanses of Australia. Downpours are frequent over the Chilean Atacama Desert, which is particularly dry. heavy rains, the floods did not spare South America either. The total damage from the willfulness of the elements amounted to about 50 billion dollars.
The cause of all these disasters, meteorologists believe the phenomenon of El Niño.
The term "El Niño" was first used in 1892 at the congress of the Geographical Society in Lima. Captain Camilo Carrilo reported that Peruvian sailors gave the name "El Niño" to the warm northern current, as it is best seen on Catholic Christmas. In 1923, Gilbert Thomas Walker began to study the zonal convection circulation of the atmosphere in the equatorial zone of the Pacific Ocean and introduced the terms "Southern Oscillation", "El Niño" and "La Niña". Until the end of the 20th century, his work remained known only in narrow circles, until the connection between El Niño and the planet's climate change was established.
El Niño means “baby” in Spanish. This affectionate name only reflects the fact that El Niño most often starts around the Christmas holidays, and fishermen west coast South America connected it with the name of Jesus in infancy.
In normal years, along the entire Pacific coast of South America, due to the coastal rise of cold deep waters caused by the surface cold Peruvian current, the ocean surface temperature fluctuates within narrow seasonal limits - from 15°C to 19°C. During the El Niño period, the ocean surface temperature in the coastal zone rises by 6-10°C. As evidenced by geological and paleoclimatic studies, the mentioned phenomenon exists for at least 100 thousand years. Fluctuations in the temperature of the surface layer of the ocean from extremely warm to neutral or cold occur with periods of 2 to 10 years. Currently, the term "El Niño" is used in relation to situations where abnormally warm surface water occupy not only the coastal region near South America, but also most of the tropical zone of the Pacific Ocean up to the 180th meridian.
There is a constant warm current, originating from the coast of Peru and stretching to the archipelago lying southeast of the Asian continent. It is an elongated tongue of heated water, equal in area to the territory of the United States. The heated water evaporates intensively and "pumps" the atmosphere with energy. Clouds form over the warm ocean. Usually trade winds (constantly blowing east winds V tropical zone) drive a layer of this warm water from the American coast towards Asia. Approximately in the region of Indonesia, the current stops, and monsoon rains pour over southern Asia.
During El Niño near the equator, this current warms up more than usual, so the trade winds weaken or do not blow at all. The heated water spreads to the sides, goes back to the American coast. An anomalous convection zone appears. Rains and hurricanes hit Central and South America. Over the past 20 years, there have been five active El Niño cycles: 1982-83, 1986-87, 1991-1993, 1994-95 and 1997-98.
The La Niño phenomenon, the opposite of El Niño, manifests itself as a drop in surface water temperature below the climatic norm in the eastern tropical Pacific. Such cycles were observed in 1984-85, 1988-89 and 1995-96. Unusually cold weather sets in the East Pacific during this period. During the formation of La Niño, the trade winds (east) winds from the west coast of both Americas increase significantly. The winds shift the zone of warm water and the "language" of cold waters stretches for 5000 km, exactly in the place (Ecuador - Samoa Islands), where during El Niño there should be a belt of warm waters. During this period, powerful monsoon rains are observed in Indochina, India and Australia. The Caribbean and the United States suffer from droughts and tornadoes. La Niño, like El Niño, most often occurs from December to March. The difference is that El Niño occurs on average once every three to four years, while La Niño occurs once every six to seven years. Both phenomena bring with them an increased number of hurricanes, but during La Niño there are three to four times more than during El Niño.
According to recent observations, the reliability of the onset of El Niño or La Niño can be determined if:
1. At the equator, in the eastern part of the Pacific Ocean, a patch of warmer water than usual (El Niño), colder (La Niño) is formed.
2. The trend is compared atmospheric pressure between the port of Darwin (Australia) and the island of Tahiti. With El Niño, pressure will be high in Tahiti and low in Darwin. With La Niño, the opposite is true.
Research over the past 50 years has established that El Niño means more than just the coordinated fluctuations in surface pressure and ocean water temperature. El Niño and La Niño are the most pronounced manifestations of interannual climate variability on a global scale. These phenomena are large-scale changes in ocean temperatures, precipitation, atmospheric circulation, and vertical air movements over the tropical Pacific.
anomalous weather on the globe during El Niño
In the tropics, there is an increase in precipitation over areas east of the central Pacific and a decrease from the norm over northern Australia, Indonesia and the Philippines. In December-February, more than normal precipitation is observed along the coast of Ecuador, in northwestern Peru, over southern Brazil, central Argentina and over the equatorial, eastern part Africa, during June-August in the western United States and over the central part of Chile. El Niño events are also responsible for large-scale air temperature anomalies around the world. During these years, there are outstanding temperature rises. Warmer than normal conditions in December-February were above southeast Asia, over Primorye, Japan, Sea of Japan, above southeast Africa and Brazil, southeastern Australia. Warmer than normal temperatures occur in June-August along the west coast of South America and over southeastern Brazil. Colder winters (December-February) occur along the southwest coast of the United States.
Abnormal weather conditions on the globe during the La Niño years
During La Niño periods, precipitation increases over the western equatorial Pacific, Indonesia and the Philippines and is almost completely absent in the eastern part. More precipitation falls in December-February in the north of South America and over South Africa, and in June-August over southeastern Australia. Dryer than normal conditions are observed over the coast of Ecuador, over northwestern Peru and the equatorial part East Africa during December-February, and over southern Brazil and central Argentina in June-August. There are large-scale deviations from the norm around the world with the largest number areas experiencing abnormally cool conditions. Cold winters in Japan and in Primorye, over southern Alaska and western, central Canada. Cool summer seasons over southeast Africa, over India and southeast Asia. More warm winters over the southwestern United States.
sources
El Niño
Southern Oscillation And El Niño(Spanish) El Nino- Kid, Boy) is a global ocean-atmospheric phenomenon. As a feature of the Pacific Ocean, El Niño and La Niña(Spanish) La Nina- Baby, Girl) are temperature fluctuations in surface water in the tropics of the eastern Pacific Ocean. The names of these phenomena, borrowed from the Spanish language of the locals and first introduced into scientific circulation in 1923 by Gilbert Thomas Walker, mean "baby" and "baby", respectively. Their influence on the climate of the southern hemisphere is difficult to overestimate. The Southern Oscillation (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.
Named after Walker, the circulation is an essential aspect of the Pacific ENSO (El Niño Southern Oscillation) phenomenon. ENSO is a set of 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 El Niño warm events, as it warms up, it expands over much of the Pacific tropics and becomes directly related to the intensity of the SOI (Southern Oscillation Index). While ENSO events are mostly between the Pacific and Indian Oceans, ENSO events in the Atlantic Ocean lag behind the first by 12-18 months. Most of the countries that are subject to ENSO events are developing countries, with economies heavily dependent on the agricultural and fishing sectors. New opportunities to predict the onset of ENSO events in three oceans could have global socio-economic implications. Since ENSO is a global and natural part of the Earth's climate, it is important to know if the change in intensity and frequency could be the result of global warming. Low frequency changes have already been detected. Inter-decadal ENSO modulations may also exist.
El Niño and La Niña
El Niño and La Niña are officially defined as long-term marine surface temperature anomalies greater than 0.5°C across the Pacific Ocean in its central tropical region. When a +0.5 °C (-0.5 °C) condition is observed for up to five months, it is classified as an El Niño (La Niña) condition. If the anomaly persists for five months or longer, then 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:
- Rising air pressure over the Indian Ocean, Indonesia and Australia.
- Drop in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean.
- The trade winds in the South Pacific are weakening or heading east.
- Warm air appears next to Peru, causing rain in the deserts.
- Warm water spreads from the western part of the Pacific Ocean to the east. She brings rain with her, causing it in areas where it is usually dry.
The warm El Niño Current, which consists of plankton-poor tropical water and is heated by its eastern branch 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, 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 several months, more extensive ocean warming occurs and its economic impact on local fisheries for the export market can be severe.
The Volcker circulation is visible on the surface as easterly trade winds, which move westward water and air heated by the sun. It also creates oceanic upwelling off the coast of Peru and Ecuador and cold waters rich in plankton flow to the surface, increasing fish stocks. The western equatorial part of the Pacific Ocean is characterized by warm, humid weather and low atmospheric pressure. The accumulated moisture falls out 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, La Niña is characterized by unusually cold temperatures in the eastern equatorial region compared to El Niño, which in turn is characterized by unusually high temperatures in the same region. Atlantic tropical cyclone activity generally increases during La Niña. The La Niña condition often occurs after El Niño, especially when the latter is very strong.
Southern Oscillation Index (SOI)
The Southern Oscillation Index is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.
Long-term negative SOI values often signal El Niño episodes. These negative values are usually associated with prolonged warming in the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific trade winds and a decrease in precipitation in the east and north of Australia.
Positive SOI values are associated with strong Pacific trade winds and warming water temperatures in northern Australia, well known as the La Niña episode. The waters of the central and eastern tropical Pacific become colder during this time. Together, all of this increases the likelihood of more rainfall in eastern and northern Australia than usual.
Extensive influence of El Niño conditions
As El Niño's warm waters feed the storms, it creates an increase in rainfall in the east-central and eastern Pacific Oceans.
In South America, the El Niño effect is more pronounced than in North America. El Niño is associated with warm and very wet summers (December-February) along the coasts of northern Peru and Ecuador, causing severe flooding whenever the event is strong. Effects during February, March, April can become critical. Southern Brazil and northern Argentina also experience wetter than normal conditions, but mostly during the spring and early summer. The central region of Chile gets a mild winter with plenty of rain, and the Peruvian-Bolivian Plateau experiences occasional winter snowfalls that are unusual for this region. Dryer and warmer weather is observed in the Amazon Basin, Colombia and Central America.
The direct effects of El Niño lead to a decrease in 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 west of the Antarctic Peninsula, Ross Land, the Bellingshausen and Amundsen seas are covered with large amounts of snow and ice during El Niño. The latter two and the Wedell Sea are getting warmer and under higher atmospheric pressure.
In North America, winters tend to be warmer than usual in the Midwest and Canada, while it is getting wetter in central and southern California, northwestern Mexico, and the southeastern United States. The Pacific Northwest states, in other words, are drained during El Niño. Conversely, during La Niña, the US Midwest dries up. El Niño is also associated with a decrease in Atlantic hurricane activity.
Eastern Africa, including Kenya, Tanzania and the White Nile Basin, experience prolonged rains from March to May. Droughts haunt the southern and central regions of Africa from December to February, mainly Zambia, Zimbabwe, Mozambique and Botswana.
Warm Basin of the Western Hemisphere
A study of climate data has shown that there is an unusual warming of the Western Hemisphere Warm Basin in about half of the post-El Niño summers. This affects the weather in the region and seems to be related to the North Atlantic Oscillation.
Atlantic effect
An El Niño-like effect is sometimes observed in the Atlantic Ocean, where the water along the equatorial African coast is getting warmer, while off the coast of Brazil it is getting colder. This can be attributed to the 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 an abundance of seabirds whose droppings support the fertilizer industry.
The local fishing industry along the coastline may be short of fish during long El Niño events. The largest global fish collapse due to overfishing, which occurred in 1972 during El Niño, led to a decrease in the population of Peruvian anchovies. During the events of 1982-83, populations of southern horse mackerel and anchovies decreased. Although the number of shells in warm water increased, but the hake went deeper into the cold water, and the shrimps and sardines went south. But the catch of some other fish species has been increased, for example, the common horse mackerel increased its population during warm events.
Changes in location and types of fish due to changing conditions have provided challenges for the fishing industry. The Peruvian sardine left due to El Nino to the Chilean coast. Other conditions have only led to further complications, such as the government of Chile in 1991 created restrictions on fishing.
It is postulated that El Niño led to the disappearance of the Mochico Indian tribe and other tribes of the pre-Columbian Peruvian culture.
Causes of El Niño
The mechanisms that can trigger El Niño events are still under investigation. It is difficult to find patterns that can show causes or allow predictions to be made.
History of the theory
The first mention of the term "El Niño" refers to the city, when Captain Camilo Carrilo reported at the congress of the Geographical Society in Lima that Peruvian sailors called the warm north current "El Niño", since it is most noticeable in the Christmas area. However, even then, the phenomenon was only interesting because of its biological impact on the efficiency of the fertilizer industry.
Normal conditions along the western Peruvian coast are a cold south current (Peruvian current) with upwelling water; upwelling of plankton 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 earth. A connection to flooding has been reported in Peset and Eguiguren.
Towards the end of the nineteenth century, interest arose 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 in d. In d. Gilbert Walker was the first to coin the term "Southern Oscillation".
For most of the twentieth century, El Niño was considered a large local phenomenon.
The history of the phenomenon
ENSO conditions have happened every 2-7 years for at least the last 300 years, but most have been mild.
Big 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 it was unusual for the 1997-1998 period that El Niño was very frequent (but mostly weak).
El Niño in the history of civilization
Scientists tried to establish why at the turn of the 10th century AD, at opposite ends of the earth, the two largest civilizations of that time almost simultaneously ceased to exist. We are talking about the Maya Indians and the fall of the Chinese Tang dynasty, followed by a period of internecine strife.
Both civilizations were located in monsoonal regions, the moistening of which depends on the seasonal precipitation. However, at the indicated time, apparently, the rainy season was not able to provide the amount of moisture sufficient for the development of agriculture.
The ensuing drought and subsequent famine led to the decline of these civilizations, the researchers believe. They attribute 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, which causes droughts in traditionally wet regions and floods in dry ones.
Scientists arrived at these conclusions by examining the nature of sedimentary deposits in China and Mesoamerica dating back to the specified period. The last emperor of the Tang Dynasty died in 907 AD, and the last known Mayan calendar dates from 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 discovery of the beginning of the event La Niña in the Pacific Ocean. (Reuters/YahooNews)
Literature
- Cesar N. Caviedes, 2001. El Nino 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
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| Changing of the climate | Paleoclimatology El Niño Geochemical carbon cycle Proterozoic glaciation, Ice Age, Little Ice Age Thermal Maximum ( |
07.12.2007 14:23
Fires and floods, droughts and hurricanes all hit our Earth together in 1997. The fires turned the forests of Indonesia to ashes, then raged across the expanses of Australia. Downpours are frequent over the Chilean Atacama Desert, which is particularly dry. Heavy rains and floods did not spare South America either. The total damage from the willfulness of the elements amounted to about 50 billion dollars. The cause of all these disasters, meteorologists believe the phenomenon of El Niño.
El Niño means "baby" in Spanish. This is the name given to the anomalous warming of the surface waters of the Pacific Ocean off the coast of Ecuador and Peru, which occurs every few years. This affectionate name only reflects the fact that El Niño most often begins around the Christmas holidays, and the fishermen of the west coast of South America associated it with the name of Jesus in infancy.
In normal years, along the entire Pacific coast of South America, due to the coastal rise of cold deep waters caused by the surface cold Peruvian current, the ocean surface temperature fluctuates within narrow seasonal limits - from 15°C to 19°C. During the El Niño period, the ocean surface temperature in the coastal zone rises by 6-10°C. As evidenced by geological and paleoclimatic studies, the mentioned phenomenon exists for at least 100 thousand years. Fluctuations in the temperature of the surface layer of the ocean from extremely warm to neutral or cold occur with periods of 2 to 10 years. Currently, the term "El Niño" is used in relation to situations where abnormally warm surface waters occupy not only the coastal region near South America, but also most of the tropical Pacific Ocean up to the 180th meridian.
There is a constant warm current, originating from the coast of Peru and stretching to the archipelago lying southeast of the Asian continent. It is an elongated tongue of heated water, equal in area to the territory of the United States. The heated water evaporates intensively and "pumps" the atmosphere with energy. Clouds form over the warm ocean. Usually trade winds (constantly blowing easterly winds in the tropical zone) drive a layer of this warm water from the American coast towards Asia. Approximately in the region of Indonesia, the current stops, and monsoon rains pour over southern Asia.
During El Niño near the equator, this current warms up more than usual, so the trade winds weaken or do not blow at all. The heated water spreads to the sides, goes back to the American coast. An anomalous convection zone appears. Rains and hurricanes hit Central and South America. Over the past 20 years, there have been five active El Niño cycles: 1982-83, 1986-87, 1991-1993, 1994-95 and 1997-98.
The La Niño phenomenon, the opposite of El Niño, manifests itself as a drop in surface water temperature below the climatic norm in the eastern tropical Pacific. Such cycles were observed in 1984-85, 1988-89 and 1995-96. Unusually cold weather sets in the East Pacific during this period. During the formation of La Niño, the trade winds (east) winds from the west coast of both Americas increase significantly. The winds shift the zone of warm water and the "language" of cold waters stretches for 5000 km, exactly in the place (Ecuador - Samoa Islands), where during El Niño there should be a belt of warm waters. During this period, powerful monsoon rains are observed in Indochina, India and Australia. The Caribbean and the United States suffer from droughts and tornadoes. La Niño, like El Niño, most often occurs from December to March. The difference is that El Niño occurs on average once every three to four years, while La Niño occurs once every six to seven years. Both phenomena bring with them an increased number of hurricanes, but during La Niño there are three to four times more than during El Niño.
According to recent observations, the reliability of the onset of El Niño or La Niño can be determined if:
1. At the equator, in the eastern Pacific Ocean, a patch of warmer water than usual (El Niño), colder (La Niño) is formed.
2. The atmospheric pressure trend between the port of Darwin (Australia) and the island of Tahiti is compared. With El Niño, pressure will be high in Tahiti and low in Darwin. With La Niño, the opposite is true.
Research over the past 50 years has established that El Niño means more than just the coordinated fluctuations in surface pressure and ocean water temperature. El Niño and La Niño are the most pronounced manifestations of interannual climate variability on a global scale. These phenomena are large-scale changes in ocean temperatures, precipitation, atmospheric circulation, and vertical air movements over the tropical Pacific.
Abnormal weather conditions on the globe during El Niño years
In the tropics, there is an increase in precipitation over areas east of the central Pacific and a decrease from the norm over northern Australia, Indonesia and the Philippines. In December-February, more than normal precipitation is observed along the coast of Ecuador, in northwestern Peru, over southern Brazil, central Argentina and over equatorial, eastern Africa, during June-August in the western United States and over central Chile.
El Niño events are also responsible for large-scale air temperature anomalies around the world. During these years, there are outstanding temperature rises. Warmer than normal conditions in December-February were over southeast Asia, over Primorye, Japan, the Sea of Japan, over southeast Africa and Brazil, southeast Australia. Warmer than normal temperatures occur in June-August along the west coast of South America and over southeastern Brazil. Colder winters (December-February) occur along the southwest coast of the United States.
Abnormal weather conditions on the globe during the La Niño years
During La Niño periods, precipitation increases over the western equatorial Pacific, Indonesia and the Philippines and is almost completely absent in the eastern part. More precipitation falls in December-February over northern South America and over South Africa, and in June-August over southeastern Australia. Dryer-than-normal conditions occur over the coast of Ecuador, over northwest Peru and equatorial east Africa during December-February, and over southern Brazil and central Argentina in June-August. There are large-scale abnormalities around the world with the largest number of areas experiencing abnormally cool conditions. Cold winters in Japan and the Primorye, over South Alaska and western, central Canada. Cool summer seasons over southeast Africa, over India and southeast Asia. Warmer winters over the US Southwest.
Some aspects of telecommunication
Despite the fact that the main events associated with El Niño occur in the tropical zone, they are closely related to processes occurring in other regions of the globe. This can be traced on long-distance communications over the territory and in time - teleconnections. During El Niño years, energy transfer to the troposphere of tropical and temperate latitudes increases. This is manifested in an increase in thermal contrasts between tropical and polar latitudes, and intensification of cyclonic and anticyclonic activity in temperate latitudes. The frequency of occurrence of cyclones and anticyclones in the northern part of the Pacific Ocean from 120°E was calculated at the Far Eastern Research Institute of Geological Research. up to 120°W It turned out that the cyclones in the band 40°-60° N.L. and anticyclones in the band 25°-40° N.L. formed in subsequent winters after El Niño more than in previous ones; processes in the winter months after El Niño are characterized by greater activity than before this period.
During the El Niño years:
1. weakened Honolulu and Asian anticyclones;
2. the summer depression over the south of Eurasia is filled, which is main reason weakening of the monsoon over India;
3. the summer depression over the Amur basin, as well as the winter Aleutian and Icelandic depressions, are more developed than usual.
On the territory of Russia during the El Niño years, areas of significant air temperature anomalies are distinguished. In spring, the temperature field is characterized by negative anomalies, that is, spring during El Niño years is usually cold in most of Russia. In summer, the center of negative anomalies over Far East and Eastern Siberia, and over Western Siberia and European part In Russia, pockets of positive air temperature anomalies appear. In the autumn months, significant air temperature anomalies over the territory of Russia were not identified. It should only be noted that in the European part of the country the temperature background is slightly lower than usual. El Niño years experience warm winters over most of the area. The center of negative anomalies can be traced only over the northeast of Eurasia.
We are currently in a weakening El Niño cycle - a period of average distribution of ocean surface temperatures. (The El Niño and La Niño events represent opposite extremes of ocean pressure and temperature cycles.)
Over the past few years, achieved great success in a comprehensive study of the El Niño phenomenon. Scientists believe that the key issues of this problem are fluctuations in the system atmosphere - ocean - Earth. In this case, atmospheric oscillations are the so-called Southern Oscillation (coordinated surface pressure oscillations in a subtropical anticyclone in the southeast Pacific Ocean and in a trough stretching from northern Australia to Indonesia), ocean oscillations - El Niño and La Niño phenomena and Earth oscillations - movement of geographic poles. Also great importance in the study of the phenomenon of El Niño is the study of the impact of external cosmic factors on the Earth's atmosphere.
Especially for Primpogoda, the leading weather forecasters of the Department of Meteorological Forecasts of the Primorsky UGMS T. D. Mikhailenko and E. Yu. Leonova
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