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Original title: Is the frequent arrival of cold air a “warm winter” or a “cold winter”? Source: CCTV News Client
Recently, cold air has entered frequently, and continuous low-temperature weather has also appeared in most areas of central and eastern China. The new corona virus is most active in cold climates. At present, the issue of whether this year is “cold winter” or “warm winter” has attracted public attention. The journalist interviewed Song Lianchun, director of the National Climate Center, and other experts.
△ Image source: Visual ChinaContinuous low-temperature climate in many places in China
Since the beginning of winter, in fact, there is more climate with low temperatures. Taking Beijing as an example, from December 1, 2020 to January 6, 2021, the city’s average temperature is -5.2 ℃, which is higher than normal temperature in the same period (-3.2 ℃) 2.0 ° C lower. The lowest temperatures of 20 weather stations nationwide in Beijing are all below -18 ° C, and the lowest temperatures of 10 stations have fallen below their all-time extremes in the same period in early January, including 6 in Shijingshan, Tongzhou, Shunyi, Changping, Xiayunling and Shangdianzi. Each station fell below the extreme historical value since its establishment, and Huairou station tied the extreme historical value since its establishment.The lowest temperature in the Beijing South Suburb Observatory is -19.6.6, the lowest since February 1966.（The lowest temperature on February 22, 1966–27.4 ℃）。
As for the whole country, affected by strong cold air, large-scale strong winds and strong cold weather will appear in the central and eastern regions of China from January 6, 2021. Affected by the cold wave , the Shandong Peninsula and Dalian in Liaoning fell to moderate snow, with heavy local snowfall; Sichuan basin, Guizhou, southern Hunan, central Jiangxi, western Zhejiang and other places snowed, and the local snow fell in Sichuan Yibin and Luzhou 8-17 Mm, there was a freezing rain in the center and southern Guizhou, southeastern Hunan and central Fujian.
The temperature drop across the country is obvious: in southern Shaanxi, eastern Hubei, central and eastern Jiangnan, and central and eastern southern China, the temperature dropped 4 ～ 8 ℃, and the local temperature dropped 9 ～ 10 ℃; the lowest temperature in Shanghai was -7.1 ℃, Nanjing -7.8 ℃, Hefei- 10.8 ℃, Wuhan -8.5 ℃, Hangzhou -6.4 ℃.
△ Image source: Visual ChinaAccording to statistics from the National Climate Center, compared to the same period in history, the frequency of cold air activity has not been much since this winter. In December 2020, there were two cold air processes that affected China, which were from December 13 to 15, 2020 (National strong cold air) And from December 29, 2020 to January 1, 2021 (National cold wave). Both were national cold air processes with a large impact area and strong cold air intensity.
So why is it so cold this year? Song Lianchun, director of the National Climate Center, said the most direct cause of the recent low temperature in a large area is that since December 2020, the high Siberian and strong East Asian winter monsoon have caused strong cold air brought by the strong northwest wind frequently invades Beijing and northern China. In the region, the extremely low temperature process that occurred on this occasion was the result of the continuous low temperature caused by the cold wave process from December 28 to December 30, 2020. At the same time, the windy weather made the wind-chill overlap effect evident.
Is it “warm winter” or “cold winter”?
Song Lianchun, director of the National Climate Center:The continuous low temperature phenomenon this winter is not too extreme historically, because winter is not over yet. The temperature is expected to gradually warm up in late January and be higher than normal. The temperature in most of the country in February will be close to normal or higher. Therefore, it cannot be said that this winter is the coldest in recent years.
△ Image source: Visual ChinaSong Lianchun introduced that from the historical sequence of the national average winter temperature in recent decades, China has shown a warming trend as a whole, and since the 1980s, most winter temperatures have been higher than the normal. In the last ten years and the winters of 2010, 2011 and 2012, the winters were significantly colder than normal. The coldest was the winter of 2011; the national average temperature in the winter of 2017 and 2018 was basically close to the same period of normal years. In the past two years, northern China The temperature in a large area was significantly lower than normal in the same period in the south. In the near future, cold air activities will be more frequent and the temperature in some areas will be low. According to the prediction of the National Climate Center, there will be cold air activities in China in the aftermath and the temperature in some areas may remain low. But whether this winter is a “warm winter” or a “cold winter” is not yet known.
Song Lianchun said that in the non-linear system of global climate, “global warming” is not like a simple connecting question, it can directly correspond to “warm winter”, “cold winter” or “is it cold in a certain process” , etc. Outcome. The overall global warming trend has not changed, but there will be hot and cold fluctuations on the interannual scale in this trend. The signals of external forcing on the two interannual scales are a measure of the climate in the context of the general trend of global warming. Modulation of interannual variability will not fundamentally change the trend of global warming, but will affect fluctuations in winter temperature in individual years.
Article Source 丨 Guangming Daily
(Edited by He Qianyi)
