What do El Nino and La Nina mean? Please explain in detail, thank you.

ELNINO El Nino in mbth? O phenomenon

A summary of El Nino phenomenon

El Nino phenomenon, also known as El Nino current, is a climatic phenomenon caused by the imbalance between the ocean and the atmosphere in the equatorial Pacific. Under normal circumstances, the monsoon air flow in the tropical Pacific moves from America to Asia, keeping the surface of the Pacific Ocean warm and bringing tropical rainfall around Indonesia. However, this pattern is disturbed every 2-7 years, and the wind direction and ocean current are reversed. The heat flow in the surface of the Pacific Ocean turns eastward to America, and then takes away tropical rainfall, resulting in the so-called "El Ni? o phenomenon".

The word "El Nino" comes from Spanish, which means "El Nino". /kloc-At the beginning of the 9th century, in Spanish-speaking countries such as Ecuador and Peru in South America, fishermen found that every few years, that is, from June of 10 to March of the following year, a warm current moved southward along the coast, which significantly increased the surface seawater temperature. The Peruvian cold current originally prevailed on the east coast of the Pacific Ocean in South America. Fish that move with the cold current make Peru's fishing ground one of the three largest fishing grounds in the world. But when this warm current appears, a large number of fish who like cold water will die, leading to the extinction of fishermen. Because this phenomenon is often the most serious around Christmas, fishermen who suffer from natural disasters and are helpless are called the son of God-El Nino. Later, in science, the term was used to indicate the abnormal warming of sea surface temperature in the eastern Pacific Ocean thousands of kilometers near Peru and Ecuador. When this happens, the sea water temperature in a wide range can be 3-6 degrees Celsius higher than normal. The rising water temperature in the vast waters of the Pacific Ocean has changed the traditional equatorial currents and southeast trade winds, resulting in global climate anomalies.

The basic feature of El Nino phenomenon is that the sea surface temperature along the Pacific coast rises abnormally, the sea water level rises, and a warm current flows southward. It turns cold water in the East Pacific into warm water, causing tsunamis and storms, causing drought in some areas and excessive rainfall in others.

The whole process of El Nino is divided into occurrence period, development period, maintenance period and attenuation period, which generally lasts for about one year, and the change of atmosphere lags behind the change of seawater temperature.

Today, with the highly developed meteorological science, people have understood that the central Pacific Ocean is the main power source of summer climate change in the northern hemisphere. Usually, there is a northward Peruvian cold current in the Pacific Ocean on the west side of the South American continent, and part of it turns into an equatorial flow and moves westward. At this time, the monsoon blowing westward along the sea near the equator makes the warm current accumulate to the west side of the Pacific Ocean, while the low-level cold sea water rises to the east side, raising the sea surface temperature in the western Pacific Ocean south of the Philippines and north of New Guinea. This part of the sea area is called "equatorial warm pool", and the seawater temperature in the east of the same latitude is relatively low. There is also a temperature difference in the atmosphere over the two sea areas. The temperature in the east is low and the air pressure is high, and the cold air sinks and flows westward. The temperature in the west is high and the air pressure is low. After the hot air rises, it turns to the east. In this way, an atmospheric circulation (Walker circulation) is formed in the central Pacific Ocean, where the cold air at sea level flows westward and the hot air at high altitude flows eastward. This circulation forms a southeast wind near the sea level. But sometimes, this pressure difference will be lower than the multi-year average, and sometimes it will increase. This phenomenon of atmospheric change is called "Southern Oscillation". In 1960s, meteorologists found that El Nino was closely related to the Southern Oscillation. When the pressure difference decreased, El Nino appeared. After El Nino, due to the warming of warm current, the monsoon flowing from east to west in the Pacific Ocean was greatly weakened, which significantly changed the atmospheric circulation and greatly affected the climate of countries along the Pacific Ocean. The originally wet area was dry, and there was a flood in the dry area. When this pressure difference increases, the seawater temperature will drop abnormally, which is called "La Nina phenomenon".

After the 1960s, with the progress of observation methods and the development of science, it was found that El Ni? o phenomenon not only appeared in the coastal areas of South America and other countries, but also spread all the sea areas along the equator of the eastern Pacific Ocean and countries around the Pacific Ocean. In some years, even the Indian Ocean coast will be affected by the climate anomaly caused by El Ni? o, and a series of natural disasters will occur. Generally speaking, it makes the climate in the southern hemisphere hotter and drier, and the climate in the northern hemisphere colder and wetter.

In recent years, scientists have put forward some new explanations for the El Ni? o phenomenon, that is, El Ni? o may be related to submarine earthquakes, changes in seawater salinity and changes in atmospheric circulation.

El Nino occurs periodically, about once every 2-7 years. During the 20 years from 65438 to 0997, El Nino occurred five times in 76-77, 82-83, 86-87, 9 1-93 and 94-95 respectively. The El Ni? o phenomenon during 1982- 1983 was the most serious since this century, which caused about 1500 deaths and 8 billion US dollars in property losses all over the world. After entering the 1990s, with global warming, El Nino phenomenon appeared more and more frequently.

Due to the development of science and technology and the attention of countries all over the world, scientists have deepened their understanding of this climate anomaly by adopting a series of scientific research activities such as forecasting model, ocean observation and satellite reconnaissance, and air-sea coupling. Firstly, it is recognized that the physical process of El Ni? o phenomenon is the result of the interaction between the ocean and the atmosphere, that is, the change of ocean temperature is related to the atmosphere. Therefore, after 1980s, scientists called El Nino "Anceaux". Secondly, tropical ocean warming occurs not only in the Chilean waters of South America, but also in the eastern and western Pacific. No matter where it happens, it will quickly lead to obvious global climate anomalies. This is the strongest signal of climate change, which will lead to serious natural disasters, such as droughts and floods in many parts of the world.

El Nino means "child" in Spanish. El Nino is a phenomenon that leads to an abnormal rise in sea surface temperature around Christmas in the cold ocean current area on the west coast of the United States. It is like a "warm pool", which changes the atmospheric heating field through the change of surface temperature, thus bringing changes to the weather in various places, causing floods in the original dry and rainy places, while the rainy places are prone to long-term drought and lack of rain.

From the position of main rain belts in China from June to August, 75% of the rain belts are located in the Yangtze River and Huaihe River basins in El Ni? o year and summer. Figuratively speaking, the low-frequency oscillation of tropical atmospheric circulation can be compared to tropical heartbeat. The occurrence of El Nino events is like a heart attack in the tropics, which makes the regular low-frequency oscillation abnormal.

When the above El Nino phenomenon occurred, it spread all over the central, eastern and Pacific oceans, and the positive anomaly of surface water temperature was as high as 3℃ or above. The strong rise in seawater temperature has led to a great decrease in plankton in the water, which has hit Peru's fishery production and led to floods or droughts in Ecuador and other equatorial Pacific regions. This El Nino phenomenon is called El Nino event. It is generally believed that the sea surface temperature anomaly for three consecutive months is above 0.5℃, which can be considered as an El Ni? o event. On the contrary, if the negative sea surface temperature anomaly along the coast of South America is above 0.5℃ for three consecutive months, it is considered as an anti-El Ni? o event, also known as La Ni? a event. At present, according to the research of meteorologists, it is generally believed that the occurrence of El Ni? o event is a harbinger of climate disasters in many parts of the world, so its monitoring has become an important content in climate monitoring.

El Nino has a serious impact on the climate in China.

First, the number of typhoons has decreased. After the El Ni? o phenomenon, the number of tropical storms (typhoons) in the northwest Pacific and the number of landings in China's coastal areas are less than normal.

Secondly, the northern part of China is prone to high temperature and drought in summer. Usually in El Nino, the summer monsoon in China is weak, and the monsoon rain belt is south, which is located in the middle of China or south of the Yangtze River. Drought and high temperature often occur in summer in northern China. 1997 After the strong El Ni? o, the drought and high temperature in northern China were very obvious.

Third, southern China is prone to low temperatures and floods. One year after El Nino, the southern part of China, including the Yangtze River basin and the south of the Yangtze River, is prone to floods. The once-in-a-century floods in China, such as 193 1, 1954, 1998, all occurred one year after El Nino ... El Nino was one of the important factors that affected the 1998 catastrophic floods in China.

Finally, in the winter after El Nino, the northern part of China is prone to warm winters.

According to the meteorological data in recent 50 years, after El Nino, there is a high probability of high temperature in winter in China, and summer precipitation in southern China tends to be more in the following year, while large-scale drought often occurs in northern China.

According to historical records, since 1950, there have been 13 El Nino phenomena all over the world. The one that happened in 1997 and continues to this day is the most serious. Mainly manifested in: from the northern hemisphere to the southern hemisphere, from Africa to Latin America, the climate has become weird and incredible. A cool place is like a fire. It suddenly snows in warm spring, but it doesn't rain when the rainy season comes, but floods in dry season. .....

Scientists believe that the occurrence of El Nino phenomenon is related to the deterioration of human natural environment, the direct result of the intensification of global greenhouse effect, and the result of human beings demanding too much from nature and not paying attention to environmental protection.

According to the research on the relationship between the change law of solar activity and El Ni? o in the past hundred years, scientists found that the period from sunspot reduction to valley value is the frequent period of El Ni? o, with two or three El Ni? o occurrences.

La Nina means "La Nina" in Spanish-"little girl, saint", which is the opposite of El Ni? o phenomenon. It refers to the abnormal drop of water temperature in the eastern Pacific near the equator, which is characterized by obvious cooling in the eastern Pacific, accompanied by global climate chaos, and always appears after El Ni? o phenomenon.

Meteorologists and oceanographers use it to refer to the large-scale continuous abnormal cooling of seawater in the eastern and central equatorial Pacific (the surface temperature of seawater is lower than the climate average by more than 0.5℃ for more than 6 months). La Nina is also known as the anti-El Nino phenomenon.

The last La Nina phenomenon appeared in 1998 and lasted until the spring of 2000. El Nino and La Nina usually appear alternately, which have roughly opposite impacts on the climate. Through the energy exchange between the ocean and the atmosphere, the atmospheric circulation is changed, thus affecting climate change. According to the monitoring data in recent 50 years, the frequency and intensity of El Nino are more than La Nina.

La Nina often happens after El Nino, but it doesn't always happen. It takes about four years for El Nino and La Nina to transform into each other.

Chinese oceanographers believe that the catastrophic flood disaster in China in 1998 was caused by "El Nino-La Nina phenomenon" and ecological deterioration in the Yangtze River basin.

Oceanographers and meteorologists in China have noticed that last year's El Ni? o phenomenon (ocean warming) in the tropical Pacific turned into La Ni? a phenomenon (seawater cooling) within one month. This unprecedented situation is one of the reasons for the surge in rainfall in the Yangtze River basin.

The El Nino phenomenon made the climate in China abnormal. 1998 from June to July, there was frequent rainfall in the south of the Yangtze River and South China, and serious floods occurred in the Yangtze River basin and the two lakes basin. The water level of some rivers has exceeded the warning water level for a long time, and the rainfall in parts of Guangdong, Guangxi and Yunnan is also above 50%. Waterlogging also occurs in parts of North China and Northeast China. La Nina can also cause climate anomalies. Chao Jiping, an academician of the Chinese Academy of Sciences and honorary director of the National Marine Environmental Forecasting Research Center, told reporters that the current situation is that the influence of El Ni? o has not completely disappeared, but the influence of La Ni? a has started again, which makes the climate state in China extremely complicated. Generally speaking, after the large-scale warm and humid air caused by El Nino moves to the higher latitudes in the northern hemisphere, it meets the cold air in the north and exchanges cold and warm, resulting in an increase in rainfall. But after June, summer came and the rain belt moved northward, so the news period in the Yangtze River Basin should be over. But then La Nina appeared, the air in the south became cold and sank, and the warm and humid airflow that had moved northward returned to fill the vacuum. In fact, the subtropical high reached 30 degrees north latitude at 10 in July, and suddenly retreated southward to 18 degrees north latitude. This phenomenon has never happened in history.