Traditional Culture Encyclopedia - Weather forecast - What does La Nina mean? thank you

What does La Nina mean? thank you

La Nina refers to the phenomenon that the sea surface temperature in the eastern and central equatorial Pacific Ocean continues to be abnormally cold (just the opposite of El Ni? o phenomenon). This is a new term used in meteorology and oceanography. It means "little girl", just the opposite of El Nino, which means "El Nino". It is also called "anti-El Nino" or "cold event".

The meaning of a word

La Nina means "La Nina" in Spanish-"little girl, saint", which is the reverse of El Ni? o phenomenon. It refers to the abnormal drop of water temperature in the eastern Pacific near the equator, which is manifested in the obvious cooling of 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.

El Nino and La Nina are abnormal manifestations of alternating sea surface temperature in the equatorial, Middle East and Pacific Ocean, forming a cycle. La Nina phenomenon after El Nino is not uncommon. Similarly, La Nina will be followed by El Nino. However, according to the records since 1950, the frequency of El Nino is higher than that of La Nina. Under the background of global warming, the frequency and intensity of La Nina phenomenon are slowing down. Especially in the 1990s, there were three consecutive El Ni? os from 199 1 to 1995, but there was no La Ni? a in the middle.

La Nina usually follows the El Ni? o phenomenon. La Nina will appear in the second year of El Ni? o, sometimes lasting for two or three years. During the period of 1988 ~ 1989, 1998 ~200 1 year, a strong La Nina phenomenon occurred, which made the seawater temperature in the eastern and central Pacific Ocean lower than normal 1 ~ 2℃ and1995. Some scientists believe that La Nina tends to weaken due to the trend of global warming.

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, academician of the China Academy of Sciences and honorary director of the National Marine Environmental Forecasting Research Center, said 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 of 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, when summer comes and the rain belt moves northward, the flood season 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.

La Nina is a modified transitional phenomenon after El Nino. This hydrological feature will cause the water temperature in the eastern Pacific to drop, which will lead to drought. On the contrary, the water temperature in the western Pacific will rise, and the precipitation will be significantly higher than normal. Scientists believe that La Nina, a hydrological phenomenon, will not have a significant impact on the world climate, but will bring more rainfall to Guangdong, Fujian, Zhejiang and even the entire southeast coast in a certain period of time.

condition

El Nino and La Nina are far from the tropics.

In September 2000, NASA said that in the past three years, El Nino and La Nina caused abnormal weather.

They will no longer affect the tropics, but other regions will also be affected by them. The temperature and water level in tropical Atlantic and Pacific have returned to normal levels. The water level in the central Pacific Ocean is higher14 ~ 32cm than normal, and the water level in Bering Sea and gulf of alaska is 5 ~13cm lower than normal. William Patzelt, an oceanographer at the agency's Jet Propulsion Laboratory, said that the current calm began with the disappearance of La Nina three months ago. He believes that the global climate system has returned to the state of three years ago.

La Nina phenomenon is decreasing.

The following content was published in 2007, but the facts have overturned this theory. It can be seen from the snowstorm in the south in early 2008 that La Nina has not disappeared.

———2008.0 1

The latest ocean observation data sent back by Poseidon satellites in France and the United States show that the La Nina phenomenon affecting the Pacific Ocean has obviously weakened in the past two years, and the world's largest ocean will restore its former "tranquility".

"La Nina" literally means "girl" and refers to a phenomenon of abnormal water temperature change in the eastern Pacific Ocean near the equator. La Nina phenomenon is formed after the huge cold water area caused by El Nino surfaced in the East Pacific Ocean. Because of its characteristics, it is also called "anti-El Nino" phenomenon. La Nina phenomenon is marked by hurricane, rainstorm and severe cold, which, together with El Ni? o phenomenon, will cause serious global climate anomalies.

According to French experts, "La Nina" usually appears after "El Nino". Usually, these two phenomena each last for about a year. However, the "La Nina" phenomenon, which started at 1998, lasted for two years and didn't begin to weaken until June this year (2007). They said that the current research could not explain why the La Ni? a phenomenon and the previous El Ni? o phenomenon were extremely strong, nor could it explain why the La Ni? a phenomenon lasted for one year longer than before.

Researchers observed signs of "La Nina" weakening twice in June and June last year, but later results proved that these were just illusions. After a little breathing, "La Nina" made a comeback again. French experts stressed that the latest data sent back by this satellite shows that the phenomenon of "La Nina" has obviously weakened, and this time the "girl" is really old.

cause

The motion of the ocean surface is mainly constrained by the sea surface wind. Because of the existence of trade winds, a large amount of warm water is blown to the equatorial western Pacific Ocean and blown away in the equatorial eastern Pacific Ocean, which is mainly supplemented by cold water below the sea surface. The SST in the equatorial eastern Pacific is obviously lower than that in the western Pacific. When the trade winds strengthen, the upwelling phenomenon of deep seawater in the equatorial eastern Pacific becomes more intense, resulting in abnormally low sea surface temperature, which makes the airflow in the equatorial eastern Pacific sink, while the upward movement of the airflow in the equatorial western Pacific intensifies, which is conducive to the strengthening of the trade winds, thus further aggravating the development of cold water in the equatorial eastern Pacific and triggering the so-called La Nina phenomenon.

Influence of La Nina on Climate in China

The following year refers to 2007.

In the first half of the year, the national climate showed a diversified trend. After research and analysis, climate experts initially believe that La Nina phenomenon is the main reason that affects China's climate in the first half of the year.

Zhao Zhenguo, a researcher at the National Climate Center, believes that this year, due to the La Ni? a phenomenon, the water temperature in the equatorial eastern Pacific is low and the meridional circulation in East Asia is abnormal, resulting in the northerly airflow prevailing in northern China since the spring, while the warm and humid airflow in the southeast is relatively weak. It leads to frequent strong cold waves and strong winds in the north, but the rainfall continues to be less and the temperature remains high.

According to statistics, sandstorms occurred frequently in northern China this spring. From March to April, a large-scale sandstorm 12 occurred, affecting northwest, north, northeast, Huanghuai and even Jianghuai areas. In May, there were three regional or local sandstorms in northwest China, which were rare in the same period of nearly 50 years. Chen Yu, a climate expert, said that in the past 50 years, the frequency of dusty weather in northwest China has increased year by year.

Lu, a senior engineer of the National Climate Center, said that since 300 AD, there have been five frequent sandstorm events in China, each lasting about 90 years. In the past 10 years, sandstorm events showed a significant increase trend.

Talking about the causes of sandstorms, Chen Yu believes that the formation and scale of sandstorms depend on two factors: environment and climate. From the environmental point of view, the increasingly serious desertification problem can not be ignored. However, "there is no smoke without fire". From the climate point of view, the temperature in the northern region has risen rapidly since February this year, with a high range of 2 to 3 degrees Celsius, which led to the early thawing of soil and the emergence of a large number of dry soil layers. At this time, the rainy season has not yet arrived. Affected by La Ni? a phenomenon, windy weather occurred continuously in the northern region, and the gale immediately formed a sandstorm.

High temperature and little rain in the north are also hot topics. From March to May this year, the national average temperature reached 196 1, which was the highest in the same period, especially in the north. Since February, there has been less precipitation in most areas north of the Yangtze River. For four consecutive months, the total precipitation was less than 100 mm, and less than 50 mm in North China and Northwest China, which was more than 50% less than normal. Especially from February to April, the average precipitation in the northern region was only 23 mm, which was the least since the founding of the People's Republic of China. The combined effect of high temperature and little rain led to the rapid decline of soil water content in the northern region, and the worst spring drought occurred since the 1990s.

Zhao Zhenguo said that since 1992, except 1998, the precipitation in North China from February to April in other years was lower than the multi-year average, especially since June last year, the precipitation in North China has been less and the soil moisture has been very poor. At this time, under the influence of La Nina phenomenon, the northerly airflow prevails in northern China, while the warm and humid airflow in the southeast is relatively weak. Coupled with the unfavorable cooperation of cold and warm air, the ideal rainfall conditions in the northern region have not been formed, resulting in continuous lack of rain and drought.

During the drought-resistant period in the north, heavy rains occurred frequently in some areas south of the Yangtze River. In this regard, Lu pointed out that the heavy rain in the south is the result of local strong convective weather, and the precipitation is normal in a wide range of river basins.

When talking about the overall climate characteristics and development trend of China, Lu said that from the global climate change trend in recent years, the overall trend is diversified, which is mainly the result of the alternating effects of El Ni? o and La Ni? a phenomena under the background of global warming. In this environment, China cannot be a peaceful "Xanadu". He said that the national meteorological department is paying close attention to the future atmospheric climate changes and making timely forecasts to minimize the losses caused by disastrous climate.

Relationship between Climate Anomaly and La Nina in 2008

We are in La Nina state this year, that is, the SST in the equatorial eastern Pacific is 0.5 degrees lower than normal, which has a very obvious impact on China's climate. Under the influence of La Nina phenomenon, the meridional circulation in East Asia is abnormal, which is very beneficial to the southward movement of cold air in northern China. It has given us a cold winter, so we can see that this cold winter has already appeared this year.

La Nina is just one of the reasons, and another reason for the formation of heavy snow is as follows:

Since 2008, the high pressure in Asia has been very active, forming a cold air mass in the south, affecting China, and there has been a large-scale gale and cooling weather. However, due to the active warm air mass in the south this year, a large number of warm and humid air currents from the Pacific Ocean and the Indian Ocean frequently patronize the southern region. When the powerful cold air mass from Mongolia and Siberia quickly moved south to meet the warm and humid air mass, the cold and warm air just merged into one. Affected by these two air currents, there have been more rainy and snowy weather recently, especially in the Yangtze River basin, and the low temperature weather has lasted for a long time. If there is only a strong cold air mass without a large amount of water vapor provided by warm and humid air mass, there will only be strong winds and cool weather in the south; If there is only a large amount of water vapor provided by warm and humid air masses, there will be no disastrous weather at all without the arrival of cold air masses. When both are ready, disaster comes.

At the same time, when China was severely hit by a snowstorm, the temperature in the central United States dropped by 20 degrees Celsius, and snowstorms appeared from time to time (2008+0); Central Asia, which has not snowed for a hundred years, suddenly snowed 10mm, setting a new record for Baghdad 100 (2007+02). In the summer of 2007, the floods in western Europe were serious, and Britain and France suffered huge losses (summer of 2007). Since the beginning of winter, the temperature in the northern edge of Russia has hit a new low, once reaching MINUS 50 degrees Celsius ... La Nina is still not over, and the situation is still very grim. ...

La Nina-Where are you from?

Last year, after the "El Nino" phenomenon that lasted for more than a year quickly disappeared, "La Nina" immediately appeared in black and pink. So what is La Nina?

So, how was La Nina formed? El Nino is related to the warming of sea surface temperature and the weakening of trade winds in the equatorial Middle East Pacific, while La Nina is related to the cooling of sea surface temperature and the strengthening of trade winds in the equatorial Middle East Pacific. So La Nina is actually the product of the interaction between tropical ocean and atmosphere. Trade winds refer to the prevailing winds blowing from tropical regions to equatorial regions in the lower atmosphere, which are called "northeast trade winds" in the northern hemisphere and "southeast trade winds" in the southern hemisphere. The Spaniards who lived in South America a long time ago used this continuous easterly wind to sail to Southeast Asia for business activities. So trade winds are also called trade winds.

La Nina also has an impact on the climate. La Nina is the opposite of El Ni? o. With the disappearance of El Ni? o and the arrival of La Ni? a, the weather and climate disasters in many parts of the world will also change. Generally speaking, La Nina is not very gentle and will bring disaster to many parts of the world. Its climate impact is roughly opposite to that of El Nino, but its intensity and impact are not as good as that of El Nino.

But human beings should reflect on why natural disasters have occurred so frequently since the 20th century.

How does La Nina affect the climate in spring and summer this year?

Influenced by La Nina event in equatorial Pacific and abnormal atmospheric circulation in Europe and Asia, there have been four large-scale low-temperature freezing weather processes in southern China since 1 this year. According to the latest forecast of the National Climate Center, this La Nina event will last until the summer of 2008, which will bring meteorological disasters to China, such as drought in spring and summer, high forest fire risk rating, more sandstorms in the northern region, and increased probability of regional floods in summer.

La Nina means "little girl" in Spanish, also known as anti-El Ni? o phenomenon, which refers to the phenomenon that the sea water in the eastern and central equatorial Pacific Ocean is unusually cold in a large area, which shows that the surface temperature of the sea water is lower than the climate average by more than 0.5 and lasts for more than 6 months. La Nina phenomenon is marked by hurricane, rainstorm and severe cold, which, together with El Ni? o phenomenon, will cause serious global climate anomalies.

The reporter learned from the National Climate Center that historically, 1954 to 1955, 1956 to 1957, 1963 to 1964,1. After comprehensively analyzing the climate changes in recent years, the National Climate Center believes that this naughty "little girl" will have the following effects on the climate in spring and summer this year:

Sowing effect of early rice in South China

It is predicted that the weather in South China (Guangdong, Guangxi and Fujian) will be worse than normal from mid-February to March this year. The northern part of South China is normal all the year round, and there are only two to four days of low temperature and rainy weather in the first half of March, which has little effect on early rice sowing, and there are many climatic conditions for spring sowing in the south of the Yangtze River.

Influence of Spring Sandstorm on Northern China

It is estimated that this spring, the number of dusty weather days in the dust-prone areas in northern China will be less than normal, but it will increase significantly compared with the same period in 2007. Strong sandstorms are more likely to occur. It is more likely that there will be more dusty days in eastern Inner Mongolia and northern Hebei.

Influence on drought and forest fire risk

This spring, there is little rain and drought in the eastern part of China, and spring drought may occur in most parts of the east, among which spring drought in Jilin, Liaoning, eastern Inner Mongolia, southern North China, Huanghuai and northern Guangdong and Guangxi may be more serious, so it is necessary to strengthen drought relief work; In summer, the range of less rain in China is greater than that of more rain, and drought is more important than waterlogging. High temperature and drought may occur from the lower reaches of the Yangtze River to the northern part of the south of the Yangtze River. In addition, in spring, the temperature in northern Heilongjiang, most of Jilin and Liaoning, southern Hunan and northern Guangdong and Guangxi are higher and the precipitation is less, so the forest fire risk rating in the above forest areas is higher.

Influence of Summer on Regional Flood Disaster

This summer, the main rain belts are located in most parts of Guangxi, Yunnan-Guizhou Plateau, Chongqing, western Hubei, southern Henan, eastern Shandong, northern Hebei, Beijing-Tianjin area and most parts of Jilin-Liaoning. These areas are more likely to be flooded.

Impact on typhoon activity

In La Nina year, due to the structure that the tropical Pacific is warm in the west and cold in the east, the convection in the warm pool area of the western Pacific is active, which easily leads to more typhoon activities in summer. The typhoons generated in early summer and those affecting China in flood season may be more active, which is beneficial to the activities of typhoons going northward.

Previous article:The weather is hot and flowers are in full bloom.
Next article:Twenty-six years ago, Guizhou's "supernatural" incident: 400 acres of trees were halved. What is the truth?