Climatic phenomenon La Niña and El Niño events and their impact on health and society

La Niña (La Nina, «girl" in Spanish) is characterized by an abnormal decrease in the sea surface temperature in the central and eastern tropical Pacific Ocean. This process is the reverse of the El Nino (El Nino, «Boy"), which is associated, however, with the warming in the same area. These states follow each other at regular intervals for a year.


And El Niño and La Niña affect circuit circulation of ocean and atmospheric currents, which in turn affects the weather and climate around the globe, causing drought in some regions, storms and heavy rains — in others.

After a period of neutral cycle of El Niño — La Niña, observed in mid-2011, the tropical Pacific region in August began to cool, and from October until now observed phenomenon La Nina weak and moderate strength.

"The forecasts made on the basis of mathematical models and expert interpretation of the evidence that the La Niña is close to maximum power, and probably will slowly weaken in the coming months. However, existing methods can not predict the situation on May, so it is unclear what the situation will develop in the Pacific — whether it is El Niño, La Niña or neutral position, "- said in a statement.

Scientists note that the La Niña of 2011-2012 was much weaker than in 2010-2011. Models predict that temperatures in the Pacific Ocean close to neutral values in the period from March to May 2012.

La Niña in 2010 was accompanied by a decrease in the area of cloud and strengthening trade winds. Reducing the pressure led to heavy rains in Australia, Indonesia and South-east Asia. In addition, according to meteorologists, it is La Nina is responsible for the heavy rainfall in the south and drought in the eastern equatorial Africa, as well as the situation in the arid central regions of southwest Asia and South America.

Al-Ni? Nyo (Spanish El Nino — Baby Boy) or Southern Oscillation (born El Nino / La Nina — Southern Oscillation, ENSO) — temperature variation of surface water in the equatorial Pacific Ocean, which has a significant impact on climate. In a narrower sense, the El-Ni? Nyo — Southern Oscillation phase, in which the surface area of the hot water is moving east. Thus weaken or even cease trade winds slow upwelling in the Eastern Pacific Ocean, off the coast of Peru. The opposite phase of the oscillation is called La Niña (Spanish: La Nina — Baby Girl). The characteristic time of oscillation — from 3 to 8 years, but the strength and duration of El Niño in reality varies greatly. Thus, in 1790-1793, 1828, 1876-1878, 1891, 1925-1926, 1982-1983 and 1997-1998 were recorded strong El Niño, whereas, for example, in 1991-1992, 1993, 1994, this phenomenon often repeated, was poorly defined. El Niño 1997-1998. was so strong that it caught the attention of world public opinion and the press. Then spread the theory of the relationship with the Southern Oscillation global climate change. Since the early 1980s, El Niño occurred in 1986-1987 and 2002-2003.

Normal conditions along the west coast of Peru defined cold Peruvian current, carrying water from the south. Where the tide is turning west along the equator, from the deep basins of cold and there is a rise in plankton-rich waters, which promotes the development of an active life in the ocean. The very same cold flow determines arid climate in this part of Peru, creating deserts. Trade winds warmed distilled water in the surface layer of the western zone of the tropical Pacific Ocean, where a so-called tropical warm pool (TTB). It warmed water to depths of 100-200 m Walker atmospheric circulation, manifested in the form of the trade winds, coupled with low pressure over the area of Indonesia, resulting in the fact that at this point the level of the Pacific Ocean to 60 cm higher than in the eastern part . And the water temperature is up to 29 — 30 ° C to 22 — 24 ° C along the coast of Peru. However, everything changes with the onset of El Niño. Trade winds weaken, TTB spreads, and the vast area of the Pacific Ocean there is an increase in water temperature. In Peru followed by a cold current moving from the west to the coast of Peru warm water masses, upwelling weakens, dies without food fish, and the western desert winds bring in moist air masses, rainfall, causing floods even. The onset of El Niño reduces the activity of Atlantic tropical cyclones.

The first mention of the term "El Niño" refers to 1892, when Captain Camilo Carreno told a congress of the Geographical Society of Lima that Peruvian sailors named the warm northern current "El Niño", as it is most noticeable during the Catholic Christmas. In 1893, Charles Todd suggested that droughts in India and Australia are at one and the same time. Pointed to the same in 1904, and Norman Lockyer. The connection of the warm currents off the coast of northern Peru with floods in the country was reported in 1895 and Pezet Eguiguren. Southern Oscillation phenomenon was first described in 1923 by Gilbert Thomas Walker. He introduced the terms themselves Southern Oscillation, El Niño and La Niña, considered zonal convective circulation in the atmosphere in the equatorial zone of the Pacific Ocean, we now get his name. For a long time, the phenomenon did not pay almost no attention, believing it to regional. Only at the end of XX century. explain the connection with the El Nino climate.

QUANTITATIVE DESCRIPTION

At present, the quantitative description of the El Niño and La Niña are defined as the temperature anomalies of the surface layer of the equatorial Pacific, of not less than 5 months, lead to rejection of the water temperature at 0,5 ° C in the b? Olshuyu (El Niño) or less (La Niña) side.

The first signs of the El Niño:

Increasing air pressure over the Indian Ocean, Indonesia and Australia.

The pressure drop over Tahiti, over the central and eastern Pacific.

The weakening of the trade winds in the South Pacific until their termination and changes in wind direction to the west.
Warm air mass in Peru, the rains in the Peruvian desert.

By itself, higher water temperatures off the coast of Peru at 0,5 ° C is considered to be a condition for the occurrence of El Niño. Usually, this anomaly can persist for several weeks, and then safely disappear. It is only a five-month anomaly is classified as El Niño, can cause substantial damage to the economy of the region by falling fish catches.

To describe the El Niño is also used Southern Oscillation Index (born Southern Oscillation Index, SOI). It is calculated as the difference in pressure over Tahiti and of Darwin (Australia). Negative values of the index indicate the phase of El Niño and positive — of La Niña.

Strong El Niño event on climate DIFFERENT REGIONS

In South America, El Niño effect is most pronounced. Usually this phenomenon is very warm and humid summers (December to February) on the northern coast of Peru and Ecuador. If El Niño strongly, it causes severe floods. Such, for example, occurred in January 2011. Southern Brazil and northern Argentina also experience wetter than normal periods, but mainly in the spring and early summer. In the center of Chile observed mild winter with lots of rain, and in Peru and Bolivia are sometimes unusual for this region winter snowfalls. More dry and warm weather occurs in the Amazon, in Colombia and Central America. In Indonesia, the humidity decreases, increasing the risk of forest fires. This also applies to the Philippines and northern Australia. From June to August, dry weather occurs in Queensland, Victoria, New South Wales and eastern Tasmania. In the West Antarctic Peninsula, Earth Ross, Bellingshausen and Amundsen seas covered with lots of snow and ice. This increases the pressure and become warmer. In North America, typically, winters are warmer than in the Midwest and Canada. In the central and southern California, in the north-west of Mexico and the southeastern United States are wet, and in the Pacific Northwest states of the U.S. — land. During La Niña, on the contrary, it becomes drier in the Midwest. El Nino also leads to reduced activity of Atlantic hurricanes. East Africa, including Kenya, Tanzania, and the White Nile basin, have long rainy season from March to May. Drought pursue from December to February the southern and central regions of Africa, mostly Zambia, Zimbabwe, Mozambique and Botswana.

Effect similar to El Niño, is sometimes observed in the Atlantic Ocean, where the water along the equatorial coast of Africa is getting warmer, and the coast of Brazil — colder. Moreover, a correlation of this circulation to El Niño.

Strong El Niño event HEALTH AND SOCIETY

El Nino causes extreme weather conditions associated with the cycles of the frequency of epidemics. El Niño is associated with an increased risk of diseases transmitted by mosquitoes: malaria, dengue fever and Rift Valley fever. Cycles of malaria associated with El Niño in India, Venezuela and Colombia. There is a correlation with outbreaks Australian Encephalitis (Murray Valley Encephalitis — MVE), which manifests itself in the south-east Australia after heavy rains and floods caused by La Niña. A striking example is the severe outbreak of Rift Valley fever, which occurred due to the El Niño after extreme rainfall in north-eastern Kenya and southern Somalia in 1997 98g.g.

It is also believed that El Niño may be associated with the cyclic occurrence of wars and civil conflicts in the country, the climate of which depends on the El Niño. The study of data from 1950 to 2004 showed that El Niño is associated with 21% of all civil conflicts of the period. The risk of a civil war in El Niño years, two times higher than during the La Niña. Probably the link between climate and military actions mediated by crop failures, which often occur in hot years.

Climatic phenomenon La Niña is associated with a decrease in water temperature in the equatorial Pacific Ocean and affects the weather almost throughout the world, has disappeared and most likely will not return until the end of 2012, said the World Meteorological Organization (WMO).

La Niña (La Nina, «girl" in Spanish) is characterized by an abnormal decrease in the sea surface temperature in the central and eastern tropical Pacific Ocean. This process is the reverse of the El Nino (El Nino, «Boy"), which is associated, however, with the warming in the same area. These states follow each other at regular intervals for a year.

Climatic phenomenon La Niña and El Niño events and their impact on health and society

After a period of neutral cycle of El Niño — La Niña, observed in mid-2011, the tropical Pacific region in August began to cool, and from October until now observed phenomenon La Nina weak and moderate strength. By early April, the La Niña has completely disappeared, and so far in the equatorial Pacific Ocean observed neutral conditions, written by experts.

"(Analysis of the simulation results) suggests that La Niña this year, probably will not return, while the likelihood of maintaining a neutral situation and occurrence of El Niño in the second half of the year are about equal," — said the WMO.

And El Niño and La Niña affect circuit circulation of ocean and atmospheric currents, which in turn affects the weather and climate around the globe, causing drought in some regions, storms and heavy rains — in others.

La Niña caused a lowering of the World Ocean

 

La Niña caused a lowering of the World Ocean

After a period of neutral cycle of El Niño — La Niña, observed in mid-2011, the tropical Pacific region in August began to cool, and from October until now observed phenomenon La Nina weak and moderate strength. By early April, the La Niña has completely disappeared, and so far in the equatorial Pacific Ocean observed neutral conditions, written by experts.

"(Analysis of the simulation results) suggests that La Niña this year, probably will not return, while the likelihood of maintaining a neutral situation and occurrence of El Niño in the second half of the year are about equal," — said the WMO.

And El Niño and La Niña affect circuit circulation of ocean and atmospheric currents, which in turn affects the weather and climate around the globe, causing drought in some regions, storms and heavy rains — in others.

La Niña caused a lowering of the World Ocean

 

La Niña caused a lowering of the World Ocean

Climatic phenomenon La Niña, which occurred in 2011, was so strong that eventually led to the fall in global sea level by as much as 5 mm. With the arrival of La Nina has been a shift in the values of the surface temperature of the Pacific Ocean and changed precipitation patterns around the world, as the earth began to drain moisture from the ocean and go to the land in the form of rain in Australia, northern South America, South-East Asia .

Alternating dominance is warm oceanic phase in Southern Oscillation phenomenon, El Nino, the cold phase, La Niña, so much can change the level of the oceans, but satellite data inevitably point out that somewhere in the 1990s, global levels Water still rising to a height of about 3 mm.
As soon as a El Nino, increase the water level starts to happen more quickly, but with a phase-change about every five years there is its opposite. The strength of the effect of a phase depends on other factors, and clearly reflects the general climate in the direction of his bitterness. Both phases of the study deals with the southern oscillation many scientists around the world, as they contain many clues to what is going on in the world, and that it expects.

Atmospheric phenomenon La Niña moderate to strong runs in the tropical Pacific Ocean to April 2011. This is stated in the newsletter about El-Nino/La-Ninya, released Monday by the World Meteorological Organization.

As highlighted in the document, all based on model forecasts predict continued or possible strengthening La Niña in the next 4-6 months, according to ITAR-TASS.

For La Nini, which this year was formed in June-July, replacing an end in April the El Niño phenomenon, characterized by unusually low water temperatures in the central and eastern equatorial Pacific. This disrupts the normal modes of tropical precipitation and atmospheric circulation. El Nino — is the opposite phenomenon, which is characterized by unusually high water temperatures in the Pacific Ocean.

The effects of these events can be felt in many parts of the world, to put it in floods, storms, droughts, promotions, or, conversely, low temperature. La Niña usually leads to strong winter showers in the eastern equatorial Pacific, Indonesia, the Philippines and the severe drought in Ecuador in northwestern Peru and equatorial eastern Africa.
In addition to this phenomenon contributes to a decrease in global temperature, and this is most obvious from December to February in the north-eastern Africa, Japan, southern Alaska, in the central and western parts of Canada, in the southeast of Brazil.

La Niña caused a lowering of the World Ocean

The World Meteorological Organization WMO / / today in Geneva said that in August this year at the equator in the Pacific again marked climatic phenomenon La Niña, which may increase the intensity and continue until the end of this year or early next year.

A recent report by the WMO El Niño and La Niña, said that the current La Niña will peak at the end of this year, but the intensity will be less than it was in the second half of 2010. Due to the uncertainty of its WMO proposes Pacific countries to closely monitor its development and promptly report possible because it drought and floods.

La Niña phenomenon implies anomalous long scale cooling water in the eastern and central Pacific Ocean near the equator, causing global climate anomaly. Previous La Niña led to a spring drought in the western Pacific Ocean, including China.

Category: Natural disasters and the environment

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