Is the weather strange recently?

Limited by global warming, but the main reason is the occurrence of El Nino phenomenon 20 14.

El Nino warm current is an abnormal natural phenomenon in the Pacific Ocean. On the west coast of South America and the eastern part of the South Pacific, there is a famous Peruvian cold current flowing from south to north. June165438+1October is the summer in the southern hemisphere. The water temperature in the southern hemisphere generally rises, and the equatorial warm current flowing eastward strengthens. At this time, the global pressure belt and wind belt move south, and the northeast trade wind crosses the equator and deflects to the left into the northwest monsoon under the action of the southern hemisphere self-deflection force (also known as geostrophic deflection force). The northwest monsoon not only weakens the southeast trade wind, which is near the west coast of Peru, but also weakens or even disappears the cold water flooding of Peru's cold current. It also blows the equatorial warm current with higher water temperature to the south, which makes the water temperature of Peru's cold current abnormally rise. This quiet and unstable ocean current is called "El Nino Warm Current".

El Nino is divided into El Nino phenomenon and El Nino event. El Nino is a climatic phenomenon of abnormal warming of sea surface temperature in tropical Pacific Ocean. Large-scale warming in the tropical Pacific will cause global climate change, but it will take more than three months to determine whether the El Ni? o event really happens.

In 20 14, the National Climate Center predicted that an El Ni? o event would occur during the year.

Chinese name

El Ni?o phenomenon

Foreign name

El Ni?o phenomenon

Another name

El Ni?o phenomenon

Applied discipline

geophysics

catalogue

1 history

2 phenomenon

3 cycles

4 research

5 have an impact

6 Future forecast

World Meteorological Organization (WMO)

national climate center

1 History Editor

Since 1970s, global abnormal weather has the characteristics of wide range, heavy disasters and long time. In this series of abnormal weather, scientists found an "El Nino" tide, which played an important role as one of the important phenomena in the ocean and atmospheric system.

"El Nino" is a Spanish transliteration, meaning "child prodigy" or "son of mind". According to legend, long ago, ancient Indians living along the coast of Peru and Ecuador paid great attention to the relationship between the ocean and the weather. They found that if the sea around Christmas is warmer than usual, it will rain heavily soon, accompanied by strange phenomena such as seabirds migrating in groups. Out of superstition, ancient Indians called this unusually warm trend "prodigy" trend, that is, "El Nino" trend.

2 phenomenon editing

The word El Nino comes from Spanish El Nino? O, originally meaning "El Nino", is used to indicate the phenomenon that the sea surface temperature on the west coast of South America (near Peru and Ecuador) extends westward and reaches the international international date line through the equatorial Pacific Ocean. [ 1]

In normal years, trade winds prevail in the southeast of this area. The easterly stress on the equatorial surface transports surface warm water to the western Pacific and accumulates there, so

Satellite-observed 1997 El Nino event

Make the sea level there rise and the sea temperature rise. In the East Pacific Ocean, under the action of the near sea breeze, the surface seawater drifts offshore, which leads to the continuous divergence of seawater quality, the decline of sea level and the upwelling of cold water in the lower layer, which leads to the decrease of sea surface temperature here. The upwelling cold seawater is rich in nutrients, which makes plankton multiply and provides sufficient bait for fish. The prosperity of fish provides abundant food for fish-eating birds, so there are many birds here. Because the seawater temperature is low, the water temperature is lower than the air temperature, and the air stratification is stable, convection is not suitable for development. The equatorial eastern Pacific has little rainfall and a dry climate. However, due to the high seawater temperature, unstable air stratification, strong convection, more precipitation and humid climate in the equatorial western Pacific Ocean. [ 1]

When the southeast wind is unusually strong, the upwelling of seawater in the equatorial eastern Pacific Ocean is extremely strong and the precipitation is extremely low. In the equatorial western Pacific, however, the seawater temperature is unusually high and the precipitation is unusually high. This is the so-called La Nina incident. [1] La Nina phenomenon, contrary to El Ni? o, refers to the abnormal decrease of seawater temperature in the East Pacific. Both of these phenomena are closely related to the global climate, which may lead to an increase in the probability of extreme weather. [2]

However, every few years, the southeast trade winds weaken, the cold water upwelling in the eastern Pacific disappears, and the surface warm water moves eastward, which leads to the rise of the equatorial eastern Pacific and the rise of the sea surface water temperature, and the coastal areas of Peru and Ecuador change from cold ocean currents to warm ocean currents. Inorganic salts in the lower seawater no longer washed up on the water surface, resulting in a large number of local plankton and fish deaths, and a large number of birds also died of hunger. Form a serious disaster. Just like this.

The time series of southern oscillation index is between 1876-20 1 1

At that time, the original dry climate turned into a rainy climate, and even caused floods. This is El Nino. [ 1]

El Nino's impact on climate is most significant in the equatorial Pacific. In the El Nino year, Indonesia, Australia, the South Asian subcontinent and northeastern Brazil all experienced drought, while it was rainy from the equatorial central Pacific to the west coast of South America. El Nino will bring devastating effects, which may lead to floods in Latin America, droughts in Australia and crop failures in India. Many observation facts also show that El Nino events have a certain influence on the circulation changes in quite far areas and even in the middle and high latitudes of the northern hemisphere through the teleconnection of air-sea interaction. It is found that when El Nino appears, it will cause continuous low temperature in summer in Japanese archipelago and northeast China, and precipitation tends to be less in most parts of China in some years. This shows the integrity of the earth's surface environment from one side: the change of one sphere will lead to the change of other spheres, the change of one region will lead to the change of other regions, and the local change will also lead to the change of the hemisphere and even the global environment. [ 1]

Three-cycle editing

El Nino is a periodic natural phenomenon, which occurs about once every seven years. Scientists have studied the global climate.

Global annual average temperature anomaly during 1950-20 1 1

El Nino is not an isolated natural phenomenon, but an aspect of global climate anomaly. In normal years, the Pacific coast on the west coast of Peru is controlled by a cold ocean current, and there is a large natural fishing ground. Once there is a climate anomaly, the cold ocean current in the eastern Pacific will be replaced by the warm ocean current. More than 30 meters thick warm ocean currents cover cold ocean currents, causing a large number of cold water plankton to be destroyed and flee or die. This is the El Nino phenomenon.

4 research editor

Meteorologists' research on El Nino is still in the 6th century.

The equatorial wind blows warm water to the west, and cold water surges up along the coast of South America.

This happened in the late 1990s. They consulted the weather archives for more than 30 years since the Second World War and found that several major "El Ni? o" phenomena occurred during the year, and all of them had global weather anomalies. 1972 global weather anomalies are related to the particularly strong El Ni? o warm current that year. This year, the worst national drought occurred in China since the founding of New China. At the same time, serious floods have occurred in some countries and regions, such as Tunisia in Africa, which is once in 200 years, and Peru is the worst flood in 40 years. At the end of 1982, the El Ni? o warm current reappeared, and the sea water in the eastern Pacific near the equator increased abnormally, and the scope became larger and larger. Around Christmas, more than 1700 seabirds perched on Christmas Island disappeared. Then it rained heavily and flooded in Peru. By 1983, El Nino had spread all over the world, and abnormal weather appeared continuously in America, Asia, Africa and Europe.

Warm water is blown to South America, and cold water is no longer upwelling to warm the ocean.

According to the latest research by American scientists, the El Ni? o phenomenon may be caused by the eruption of underwater volcanic lava. Lava spews from the crustal fault at the bottom of the ocean, transferring huge heat to the Pacific ocean current near the equator, warming the sea water, and causing abnormal water temperature and ocean current direction in the East Pacific Ocean.

Researchers in potsdam institute for climate impact research, Germany, based on high-quality temperature data, put forward a new method, which can predict the occurrence of El Ni? o in time and accurately six months to one year in advance. The study was published in the latest issue of Proceedings of the National Academy of Sciences. [ 1]

Hans Joachim Schoenhuber, co-author of the study and director of the potsdam institute for climate impact research, said: "The key is to provide people in the affected areas with more early warning time to prepare and avoid the worst effects of some El Ni? o phenomena." The new method adopts the network analysis method in the frontier methodology of physics and mathematics. These data come from more than 200 stations since 1950s, which is very important for the interactive study of climate warming between remote stations in the Pacific Ocean. [ 1]

According to this new method developed and tested by Schoenhuber, the forecast time can be advanced and the reliability can be improved. In fact, the new method correctly predicted that there was no El Ni? o event in 20 1 12 years. [ 1]

When the El Ni? o phenomenon occurs, the sea water temperature in a large area of the equatorial eastern Pacific can be several degrees Celsius higher than normal. The rising water temperature in the vast Pacific Ocean has changed the traditional equatorial current and southeast trade wind, and changed the global atmospheric circulation pattern. The most direct phenomenon is the inverse correlation of sea level pressure between the equatorial western Pacific Ocean and the Indian Ocean, that is, the Southern Oscillation (SO). During La Nina, the air pressure in the southeast Pacific increased obviously, while that in Indonesia and Australia weakened. During El Nino, the situation is just the opposite. This interaction and relationship between the ocean and the atmosphere is called "ENSO" in meteorology. This global climate oscillation is called ENSO cycle. This study mainly focuses on climate warming events. Generally speaking, the El Ni? o year is followed by the La Ni? a year. [ 1]

Schoenhuber said: "It is not clear to what extent global warming caused by human greenhouse gases will affect the ENSO model. But the latter is often regarded as the so-called detonating element in the earth system, which means that to some extent, climate change may change suddenly. Judging from the past data of the earth, higher global average temperature may increase the oscillation amplitude, so correct prediction becomes more important. " [ 1]

5 influence editing

Years with significant ENSO scale: 1790-93, 1828, 1876-78, 189 1, 1925-26,/kloc-.

Smaller years: 1986- 1987, 199 1- 1994, 1997- 1998, 2002-2008.

The ENSO phenomenon from1April 1982 to1July 1983 was the most serious in centuries. The water surface temperature in the eastern and central Pacific Ocean is about 4-5℃ higher than normal, resulting in 1300 ~ 1500 deaths and economic losses of nearly 100 billion US dollars.

The ENSO phenomenon in 1986 ~ 1987 makes the surface water temperature in the equatorial middle east Pacific about 2℃ higher than the annual average temperature. At the same time, the tropical atmospheric circulation is abnormal, and the weather in tropical areas is abnormal; Heavy rains hit northern and central Peru in South America; The flood of the Amazon River in Colombia has caused the riverbank to burst many times; There is little rain and drought in the northeast of Brazil and hot in the west; Rainfall in eastern Australia and coastal areas has decreased significantly; There is little rain and drought in South China, South Asia and North Africa.

At the beginning of 1990, the precursor phenomenon of ENSO appeared again. On June 5438+ 10 this year, the water surface temperature in equatorial waters was 0.5℃ higher than that in previous years, and that in the waters west of international date line was nearly 1℃ higher than that in previous years. The warm water layer at 28℃ near the sea surface is about 10 meter shallower than in previous years. The water level in the Pacific coast of South America is higher than normal 15 ~ 30cm.

1997- 1998 During the ENSO phenomenon, the water surface temperature in the eastern and central Pacific Ocean was about 3-4℃ higher than normal, and there were persistent rainstorms in America, persistent droughts and large-scale forest fires in Southeast Asia. This El Nino phenomenon occurred immediately after 1990- 1994, with a rare frequency but a small scale.

At the same time, the warm seawater driven by ENSO affects the movement of fish and destroys the growth of coral reefs.

Especially in El Nino year, the northwest Pacific and northeast Pacific are prone to form powerful typhoons and hurricanes. For example, in the Pacific typhoon season of 1997, there were ten category 5 typhoons with the highest power, and in the Pacific hurricane season of 1997, there were two category 5 hurricanes with the highest power: Hurricane Linda and Hurricane Guillermo. [3]

6 future forecast editing

World Meteorological Organization (WMO)

The Geneva-based World Meteorological Organization (WMO) issued a press conference on April 5, 20 14, saying that the El Ni? o phenomenon may occur in the middle of 20 14, because the seawater temperature in the equatorial Pacific has reached the precursor level of the El Ni? o warm current. [2]

According to the World Meteorological Organization, since February 20 14, the sea water temperature in the equatorial Pacific Ocean has obviously increased due to the strong westerly wind and weak trade winds. In addition, the meteorological model predicts that the temperature in this sea area will rise steadily in the coming months. [2]

The increase of seawater temperature in the equatorial Pacific is regarded as an important signal of El Ni? o phenomenon. The longer the seawater temperature exceeds the average temperature, the greater the possibility of El Ni? o phenomenon. [2]

According to the World Meteorological Organization, since the second quarter of 20 12, many indicators such as water temperature and sea level pressure in the equatorial Pacific show that the whole world is in an "El Ni? o neutral" state (that is, there is no El Ni? o or La Ni? a phenomenon), and it is expected that this state will continue until the beginning of the second quarter of this year. [2]

Michel Jarraud, Director-General of the World Meteorological Organization, said that in the past 15 years, only two years were regarded as El Ni? o years; The natural warming caused by El Nino and man-made warming factors * * * work together, which may lead to a significant increase in the global average temperature. [2]

national climate center

According to the monitoring data of the National Climate Center, the SST in most parts of the equatorial Middle East and Pacific Ocean in May 201April was 0.5℃ higher than normal, and it has entered the El Ni? o state.

This state of high sea temperature continues, and it has been basically determined that an El Ni? o event will occur in 20 14 years. Experts said that this will probably have an impact on the precipitation pattern in China. In the autumn of 20 14, there may be low temperature and rainy disasters in the south of China, autumn drought in the north, and the first frost date in the northeast autumn grain producing area may be advanced.

According to the data of National Climate Center, there have been two strong El Ni? o events in the world since 1950, namely 1982 to 1983 and 1997 to 1998, and the latest one was1. Therefore, it is particularly important to prevent and reduce losses in advance. [4]