Here comes Lanina.

According to the climate prediction conference recently organized by the National Marine Environment Prediction Center of the Ministry of natural resources, the equatorial central and eastern Pacific entered La Nina state in August this year. At present, the air sea coupling in the equatorial region is conducive to the maintenance and development of La Nina state. It is expected that a La Nina event will take place in the winter of this year and continue until next spring.

According to the national standard of "El Nino / La Nina event discrimination method", the intensity level of this event is expected to be weak to medium intensity.

La Nina will appear this winter

"According to our prediction, La Nina's state will peak this winter and then begin to decline. By the winter of this year, according to the current operational monitoring indicators, a La Nina incident can be formed. " Jia Xiaolong, deputy director of the National Climate Center, told reporters.

According to the forecast of Japan Meteorological Bureau, there is a 60% probability that La Nina will last into spring. The World Meteorological Organization (WMO) pointed out in the new edition of global seasonal climate update that La Nina phenomenon has been formed, affecting the temperature, precipitation and storm patterns in many parts of the world.

"La Nina" phenomenon generally occurs once every two to seven years. It refers to the phenomenon that the surface temperature of the equatorial and Middle East Pacific Ocean is relatively cold in a wide range compared with the same period of the year, and its intensity and duration reach certain conditions.

According to the data provided by the National Climate Center, in August 2020, the sea surface temperature in most parts of the equatorial central and eastern Pacific was lower than that in the same period of the year. The monitoring index of the key area of sea surface temperature (Ni ó o 3.4 area) was - 0.6 ℃, which was 0.3 ℃ lower than that in July; from September 1 to 20, the sea surface temperature of Ni ó o 3.4 area fluctuated, and the monitoring index was lower than - 0.5 ℃, indicating that the equatorial Middle East Pacific has entered La Nina state.

Since September, the cold water under the surface layer of the equatorial Middle East Pacific has been developing continuously, and the lower troposphere is continuously controlled by the abnormal easterly wind, which is conducive to the further development of the cold sea surface temperature in the equatorial Middle East Pacific.

Based on a comprehensive analysis of the recent monitoring of ocean and atmospheric circulation in the equatorial Pacific, combined with the prediction results of climate models at home and abroad, La Nina state is maintained in autumn and reaches its peak in winter. "With regard to the intensity of this La Nina incident, we preliminarily judged that it was a weak to moderate intensity La Nina event." Jia said.

La Nina is cold winter?

"Generally speaking, in the winter of most La Nina years, the cold air affecting China is relatively frequent, and the probability of low winter temperature in central and eastern China and most regions is relatively high." Jia Xiaolong said.

According to statistics, there have been five La Nina incidents in China since 2001. In the winter of La Nina year, the temperature in most areas of central and eastern China is generally lower than that in the same period of the year. Meanwhile, the average temperature in some areas of Inner Mongolia, northeast and North China is 1-2 ℃ lower than that in the same period of the year.

From the autumn of 2007 to the spring of 2008, 20 provinces (autonomous regions and cities) in China have experienced disastrous weather of low temperature, rain, snow and freezing for 50 years in some areas for 100 years. Behind this, there is the influence of La Nina phenomenon, and it is only a moderate intensity La Nina phenomenon.

Meteorological satellite remote sensing snow monitoring shows that the total area of snow cover is 1.282 million square kilometers. The extreme meteorological disasters of continuous low temperature, rain and snow freezing have caused serious impacts and losses on transportation, power transmission, communication facilities, agriculture and people's lives. According to the statistics of the Ministry of civil affairs, more than 11 million hectares of crops have been affected, and more than 100 million people have been affected, and the direct economic loss has exceeded 150 billion yuan.

"But we also note that in the context of global warming, the relationship between the various climate factors affecting China is very complex, and La Nina is only one of the important factors affecting China's winter climate." Jia Xiaolong stressed that on the one hand, China is affected by the tropical ocean in winter, and the cold air comes from high latitudes. Changes in atmospheric circulation in the middle and high latitudes, including changes in sea ice and snow cover, will also have a clear impact on the circulation system in the middle and high latitudes. "Therefore, our prediction of winter climate is based on the comprehensive consideration of the interaction between multiple factors."

Is the atmospheric diffusion condition better this winter?

Jia Xiaolong said that the periodicity of climate change in China this winter is very obvious, especially the temperature change. According to the current consultation opinions, the cold air affecting China this winter is still relatively frequent, and the cold air force is generally strong. In the early winter, except for the low temperature in western Inner Mongolia, Northwest China and South China, the temperature distribution in most parts of the country is normal to high.

"Around January next year, the cold air force that affects China will obviously become stronger. The temperature in the central and eastern parts of China and most areas will be lower than that of the whole year. Strong ice and snow weather may occur in the northern region, so we should pay attention to prevention." Jia Xiaolong believes that although the southern region is affected by La Nina, the possibility of large-scale and sustained low-temperature rain and snow freezing this winter is relatively small, but in the east of Southwest China and the west of Jiangnan, there will still be periodic rain and snow weather in winter.

"Generally speaking, the winter monsoon is slightly stronger this year. The circulation of cold air in the middle and high latitudes is relatively frequent, and the overall force is stronger. Under such conditions, it is expected that the meteorological conditions of air pollution diffusion in winter this year, such as the Fenwei plain and the surrounding areas of Beijing, Tianjin and Hebei will approach the average level of nearly five years. The Yangtze River area is a little different from that in recent five years. The overall situation of the three regions and 2017, 2

”Jia Xiaolong pointed out that although this year's cold air activities are relatively frequent, attention should be paid to air pollution during the intermittent period of cold air activities and great attention should be paid to it.

Source: China Environment News