La Nina phenomenon refers to the large-scale cooling of sea surface temperature in the central and eastern equatorial Pacific, accompanied by changes in tropical atmospheric circulation (wind, pressure and rainfall). Its influence on weather and climate is usually opposite to the El Ni? o phenomenon (that is, the warm period of the El Ni? o Southern Oscillation (ENSO)).
"El Nino and La Nina are the main natural driving forces of the earth's climate system. But at present, all natural climate events occur in the context of human-induced climate change, which intensifies extreme weather and affects the water cycle, "said Professor Petrie Taras, Secretary-General of the World Meteorological Organization.
"La Nina usually has a cooling effect on the global temperature, but the heat of greenhouse gases in the atmosphere is enough to offset this effect. Therefore, 2020 will remain one of the warmest years on record, and 20 16-2020 is expected to be the warmest five years on record. " Professor Talas said. "This year's La Nina phenomenon is even warmer than the previous years with strong El Ni? o phenomenon."
According to the latest report of the new ENSO of the World Meteorological Organization, the sea surface temperature in the tropical Pacific Ocean is likely to remain at La Nina level (90%) before the end of 2020, and may last until the first quarter of 20021year (55%). More than a year ago, ENSO was neutral (that is, there was neither El Nino nor La Nina). This latest bulletin is based on the forecast and expert analysis of the World Meteorological Organization's Global Long-range Forecast Production Center.
It should be noted that El Nino and La Nina are not the only factors that promote the development of global and regional climate models. Every La Ni? a or El Ni? o event is different, and their impact on regional climate may vary according to the time of year and other factors. Therefore, decision makers should always pay attention to the latest seasonal forecast to get the latest information.
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La Nina will lead to global climate anomalies. The impacts include: extreme drought in the southwestern United States and the west coast of South America, extremely high rainfall in Southeast Asia such as Australia, Indonesia, Malaysia and the Philippines, and extremely cold in the west and southeast coasts of Africa, Taiwan Province Province, Japan and the Korean Peninsula. In the northwest Pacific, the area affected by tropical cyclones will be south-west than normal.
In addition, the subtropical high will be stronger than normal, causing tropical cyclones to move west to west-northwest, and more tropical cyclones will appear in the Philippines and the South China Sea.
Interestingly, once La Nina phenomenon appears, hurricanes in the North Atlantic will be extremely active.
For example, in the Atlantic hurricane season in 2005, there were four rare hurricanes with the highest intensity, namely, Hurricane Emily, Hurricane Katrina, Hurricane Rita, Hurricane Weimar and Hurricane Mitch in the early Atlantic hurricane season of 1998, which caused heavy casualties and property losses in North America and Central America. Among them, Hurricane Tama is one of the strongest hurricanes in the North Atlantic on record.
In the 2007 Atlantic hurricane season, there were two category 5 hurricanes with the same intensity: Hurricane Dean and Hurricane Felix. In the Atlantic hurricane season of 20 17, there were also two category 5 hurricanes with the highest intensity: Hurricane irma and Hurricane Maria. In addition, La Nina phenomenon sometimes leads to the special situation that the number of typhoons in the northwest Pacific is small, but the power is super strong.