Why is it so cold this year?

Mainly because of the influence of La Nina phenomenon.

La Nina and Arctic sea ice are less, which is an important background of cold. The high or low temperature in a period of time belongs to the climate category, which is mainly the result of the interaction of atmosphere, ocean, land surface and ice and snow. If the sun heats the ocean to raise the temperature of seawater by 0.5℃, the warming and evaporation of seawater will affect the atmospheric circulation. For China, tropical sea surface temperature, Arctic sea ice and Eurasian snow are all important factors affecting winter climate.

Yuan Yuan, a researcher in the Climate Prediction Office of the National Climate Center, believes that the main reasons for the low temperature in many places since June+February, 5438 are the "four strong"-the strong meridional circulation in the middle and high latitudes of Europe and Asia, the strong ridge of the Ural Mountains, the wide trough of the Balkhash-Baikal low pressure, and the Siberian high with strong sea level pressure field, which make the cold air generally move from the northwest. From the big climate background, the development of La Nina and the abnormal lack of Arctic sea ice are two main external forcing factors.

Extended data

According to the monitoring data of meteorological department, since June 5438+February, the temperature in many parts of the country is indeed lower than that in the same period last year:

From the national average temperature anomaly chart of 12 ~ 1 ~ 22, it can be seen that the temperature in most areas of China is close to normal or low, with the number of provinces accounting for about 80% of the country, except for the northeast of Inner Mongolia, the western and northern parts of Heilongjiang, most of Tibet, Qinghai, western Sichuan and Yunnan. Among them, the temperature in northern Xinjiang, northern northwest China, most of Inner Mongolia, northern and western North China, southeastern Southwest China, western Jiangnan and western South China is 2℃ to 4℃ lower.

Niu Ruoyun, chief weather forecaster of the Central Meteorological Observatory, said that since 65438+February, due to the influence of cold air, temperatures in many places have fluctuated. For example, on September 9-13, the average temperature in most parts of the country was slightly higher than in previous years. In this case, when cold air comes, the public will feel the chill more strongly.

Take Erlianhaote, Inner Mongolia as an example. The average temperature in recent days 10 is -22.5℃, which is 7.5℃ lower than normal. The lowest temperature on February 15 is -36.4℃, which is the extreme value in the same period since 1968. The daily average temperature of Tongliao Holingol Meteorological Station 10 reached -20.8℃, which broke through the lowest extreme value (-20.5℃) of the historical average temperature of the station in the same period. The temperature is obviously low, and due to the influence of snowfall, some pastoral areas are prone to "sitting in winter snow", which is unfavorable for livestock foraging and wintering in pastoral areas. At the same time, lambs and calves are easy to freeze to death, and heating in old urban communities is also facing a severe situation.

Guiyang City, Guizhou Province, in mid-June+February, 5438, the temperature in the city was generally 3.4℃ to 4.8℃ lower than normal. Especially in the freezing weather from 14 to 17, the minimum temperature in some towns and villages in Guiyang dropped to -6℃ (the average temperature was 0.7℃ to 3.5℃), roads in many sections were frozen, and ice accumulated on transmission lines and wires.

1February 16, the freezing weather in Guiyang, Guizhou Province continued. Because the temperature has been kept below 0℃ and it is often accompanied by freezing rain at night, the leaves and grass on the highlands are covered by freezing rain.