Meteorology, what is the "El Nino phenomenon"?

El Nino phenomenon in history

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The Peruvian ocean current flowing along the coast of South America is a cold ocean current. Blown by the southeast trade wind almost parallel to the coast of Peru, the surface seawater flows offshore, and the deep seawater upwells to replenish it, and at the same time carries nutrients to the upper layer, so plankton flourishes, attracting a large number of cold-water fish such as Peruvian sardines to breed and inhabit here, making this area a famous fishing ground in the southeast Pacific. However, in some years, the southeast trade wind temporarily weakened, and the south branch of the Pacific equatorial countercurrent crossed the equator and went south along the coast of Ecuador, resulting in a rapid rise in the water temperature along the coast of Ecuador and Peru, and a large number of cold-water plankton and fish died because they did not adapt to the new environment. Because around Christmas, when the son Jesus was born, the coastal water temperature rose the most sharply, and Peruvian residents called this seasonal increase in seawater temperature El Ni? o (El Ni? o is Spanish transliteration, meaning El Ni? o).

When El Nino occurred, the catch in Peru was seriously reduced, which affected the supply of feed in the world market. Fish carcasses are piled up at the seaside, polluting the surrounding seawater; Seabirds in coastal areas and islands fled for lack of food, which affected the industrial production of guano and made workers unemployed. El Nino phenomenon not only brings great disasters to people's lives along the coast of South America, but also often leads to disastrous global climate anomalies, such as persistent worldwide floods, snowstorms, droughts and earthquakes. Newspapers generally refer to them as "El Nino phenomenon (event)", while scientists refer to the years after the monthly average sea surface temperature in a large range is higher than 1 degree as "El Nino phenomenon". During the period of 1982- 1983, the precipitation in the equatorial eastern Pacific, which is usually dry, increased greatly, and there was an abnormal rainstorm in western South America in summer. Ecuador, Peru, Chile, Paraguay and northeastern Argentina were hit by floods, and the precipitation in Ecuador was 15 times higher than that in normal years. The flood washed away the dam and flooded the farmland, leaving hundreds of thousands of people homeless. On the west coast of the United States, California coastal roads are flooded, and floods and mudslides in five States, including Nevada, are as high as 9 meters. On the west side of the Pacific Ocean, a jungle fire caused by drought in Australia killed many people. A forest fire broke out in East Kalimantan, Indonesia, affecting Malaysia and Singapore; Smoke from the fire interrupted air transport in Malaysia and forced three states to ration water supply. The high temperature in Singapore is the worst in 35 years. According to statistics, the economic loss caused by this El Ni? o event on a global scale is about $20 billion. The whole tropical Pacific can be reached from the east to the middle. Now, the word El Nino has been used by meteorologists and oceanographers to refer to the large-scale abnormal warming of seawater in the equatorial Middle East and Pacific Ocean. Studies by some experts and scholars show that El Ni? o is closely related to droughts in India, Southeast Asia, Indonesia, Australia and other places, abnormal rains in equatorial Pacific islands, Ecuador, Peru, Chile, Argentina and other countries along the Pacific coast of South America, and is also related to the reduction of tropical storms in the northwest Pacific and Atlantic Ocean, the low temperature in summer in Japan and Northeast China, and the precipitation in China.

From March 65438 to/kloc-0 to March 997, the sea level in the tropical central and eastern Pacific Ocean rose abnormally. In July, the sea surface temperature was higher than ever before, and the resulting climate change has been revealed in some areas. There are many signs that the cold water period in the equatorial eastern Pacific has ended and it has begun to change to the warm water period. Scientists believe that a new round of El Nino phenomenon has begun to take shape and will last until 1998. It is from this moment that the climate on the earth began to become chaotic.

In southern Africa, El Ni? o brought the worst drought since 1997 and threatened the famine of about 5 million people. In the western Pacific, El Nino suppressed rainfall, plunged Indonesia and Papua New Guinea into drought and triggered forest fires. Countries along the eastern Pacific, Chile, Peru, Ecuador, Argentina, Uruguay and eastern Brazil, were hit by snowstorms. Nine of Chile 13 areas were flooded, with more than 5 1000 people affected. In the border area between Argentina and Chile, the snow in the Andes is up to 4 meters deep, roads are blocked and people are surrounded. Flash floods broke out in the coastal areas of Ecuador, communication was interrupted and thousands of people were homeless. What caused this marine biological disaster was an equatorial countercurrent-El Nino warm current flowing from west to east in the northern waters of Peru cold current, which was generally weak and would not cause any impact. In the year when El Nino happened, its vitality increased. After being blocked by the South American continent, it will turn around and flow to the area where the Peru cold current is located in the south, causing the sea water temperature here to suddenly rise by 3℃ ~ 6℃. Cold water plankton and fish that once lived in this sea area died in large numbers because they did not adapt to this warm environment. Seabirds and marine animals that feed on fish starve to death or move to other places because they can't find food. In the worst days of the disaster, the sea surface and beaches of callao, the outer port of Lima, Peru, were covered with the remains of fish, seabirds and other marine animals. The decomposition of animal carcasses produces hydrogen sulfide, which discolors and stinks the seawater, blackens the underwater hulls of ships in the harbor, and splashes the buildings and cars near the harbor with the fog or sea breeze blowing to the mainland, so that the surface is coated with a layer of black, as if someone had painted it. Locals call this El Nino graffiti "callao painter".

When El Nino occurs, the abnormal rise of sea surface temperature leads to the increase of atmospheric temperature over the ocean, which destroys the dynamic balance of the normal distribution of heat and water vapor in the atmospheric circulation. This kind of sea-air change is often accompanied by disastrous weather around the world: hot and cold, sunny places are flooded, and rainy places are scorched by the hot sun. Generally speaking, when El Nino occurs, the rainfall in the central and eastern equatorial Pacific will increase greatly, causing floods, while the western Pacific such as Australia and Indonesia is dry and rainy. According to incomplete statistics, there have been 17 El Ni? o phenomena since this century (including the latest round of 1997 ~ 1998 El Ni? o phenomena). The seasons are not fixed, ranging from six months to one or two years. The intensity is also different. The incident from 1982 to 1983 was very strong and lasted for two years, with frequent disasters, causing about 1500 deaths and at least 100 billion US dollars in property losses.

Like previous times, a new round of El Nino phenomenon has also affected China. The most obvious performance is that it can weaken the summer monsoon intensity from the southeast ocean, lead to the abnormal phenomenon that the summer rainfall belt is located to the south, cause heavy rain in the south and severe drought in the north. During the period from June to August, extreme high temperature occurred in most parts of the north, and the weather in the capital Beijing was extremely sultry during this period, which made the sales of air conditioners unprecedented prosperity. In the middle and lower reaches of the Yangtze River, where the summer heat in China was located in previous years, the four "stoves" in Chongqing, Wuhan, Nanchang and Nanjing turned off twice. Due to the continuous high temperature and rare drought in northern provinces such as Shandong, the Lijin hydrological station in Shandong Province of the Yellow River was cut off for 222 days, which seriously affected industrial and agricultural production and people's lives. At the same time, the rainfall in many places in the south is much more than in previous years. It is reported that the rainfall in the first eight months of Macao 1997 exceeded the average annual rainfall in the past 40 years. The rainfall in Hong Kong has also broken the historical rainfall record. On the day of Hong Kong's return to China on July 1, the continuous heavy rain was accompanied by a grand handover ceremony from beginning to end, which was impressive. Generally speaking, under the influence of El Nino, the winter temperature in most parts of the country is higher than normal, and the phenomenon of waterlogging in the south and drought in the north is more obvious.