China Weather Network News In the past November, my country experienced three rounds of cold wave weather in succession, which was significantly more than normal. However, what is surprising is that the average temperature in most of my country's central and eastern regions in November was higher than that of the same period in normal years. .
Why is it warmer when there are more cold waves?
In the context of global warming, how has the cold wave affecting our country changed?
Will we experience more cold waves this winter?
Since the second half of this year, there have been four rounds of cold waves significantly more than usual
In October and November of this year, our country experienced four rounds of cold wave weather in succession, which was significantly higher than that of the same period in normal years.
From October 15th to 17th, the first cold wave in the second half of this year was reported early, and the Central Meteorological Observatory issued the first blue cold wave warning in the second half of the year.
The temperature in the north has plunged. The lowest temperature in Beijing dropped to minus 0.1°C on October 17, breaking the lowest record for the same period since 1969.
After this cold wave, netizens invented a new internet buzzword-spring, summer, and winter.
From November 6th to 9th, the second round of cold wave struck strongly.
The Central Meteorological Observatory has upgraded its early warning and issued the first cold wave yellow warning in the second half of this year.
In many parts of North China, the first snow was a blizzard. Tongliao, Inner Mongolia, encountered the strongest snowstorm since meteorological records. The temperature of 1.01 million square kilometers of land fell by more than 16°C.
From November 22nd to 23rd, the third round of cold wave followed.
Although the intensity is slightly inferior to the previous round, the area affected by this cold wave has a high degree of overlap with the previous round, so the superimposing effect is obvious.
Heavy snow to extremely heavy snow occurred in northeastern Heilongjiang, and the depth of snow cover generally reached 25 to 49 cm.
From November 29th to December 1st, the fourth round of cold wave "came online", and the affected areas were mainly in East China and the eastern part of Northeast China.
The temperature in Zhejiang, Jiangxi, Fujian and other places dropped sharply by more than 10°C, and strong winds of magnitude 8 or more appeared along the coast of East China.
The eastern part of Northeast China suffered the third round of heavy snowfall since the second half of this year. The depth of local snow in Heilongjiang exceeded 50 cm.
In November, the average temperature in most of the eastern part of the central and eastern parts of the three rounds of cold waves was still high
Cold waves hit frequently, is the legendary cold winter coming?
not yet.
From this national temperature anomaly map, it can be seen that although my country experienced three rounds of cold wave weather in November this year, the average temperature in the central and eastern regions was higher than in the same period of normal years, especially in eastern Inner Mongolia, eastern Northeast China and In the north, west of Huanghuai and other places, the temperature is even higher by 1 to 3°C.
Why does this happen?
Shi Yan, a meteorological analyst at China Weather.com, said that this is because after each cold wave, the temperature in various places will rise rapidly, and the temperature recovery is relatively large and lasts for a long time, so the temperature is still high on average.
In Beijing, for example.
The daily average temperature in Beijing in November this year fluctuates particularly sharply, and the two obvious "bottom dips" respectively correspond to two cold wave weather processes.
However, the warming after each "bottom dip" is also very obvious. The temperature is higher for longer than the time when the temperature is lower. Therefore, the monthly average temperature is 0.9°C higher than that of normal years.
From the perspective of a deeper circulation background, most of my country is in the mid-latitude westerly zone, and the atmospheric circulation in the westerly zone is mainly manifested by atmospheric fluctuations.
Atmospheric crests (ridges) correspond to clear weather and heat up, and troughs (troughs) correspond to low temperature rain and snow, which is what we usually call cold air.
The intensity of wave trough and wave crest are usually corresponding. The more the trough (groove) cools, the more obvious the wave crest (ridge) rebounds.
In fact, judging from the first two paths that affected my country’s cold air in November, they all belonged to the west or northwest path, and the main body of cold high pressure affected the west for a longer time.
In addition, the northeast region also has the southerly wind transporting warm and humid, so throughout November, the temperature in the central and eastern regions, especially in the northeast, was significantly higher than normal.
This is also the main reason for the frequent occurrence of cold waves in my country in November.
From the monthly cold wave statistics of the National Climate Center from 1951 to 2020, November is the month with the most cold waves.
At this time, it is in the time of seasonal transition, the summer monsoon and winter monsoon are switched, and the weather system and cold air activities are frequent.
The base temperature is higher before the cold air is affected, and the temperature drops "cliff-like" after the cold air is affected, and it is relatively easier to reach the cold wave standard.
In the mid-winter season, the base temperature is already low, and the cooling rate is often limited when cold air strikes, and there are relatively few cases of reaching the cold wave standard.
We may face more extreme cold or extreme warm events in the context of global warming
In the context of global warming, will cold wave weather become less and less?
According to statistics from the National Climate Center, from 1951 to 2020, the number of cold waves affecting our country has indeed shown an overall decreasing trend.
However, it should be noted that the overall trend is only an average, and the inter-annual changes in the number of cold waves are still relatively large.
On the other hand, fewer cold waves do not mean that the power of cold waves is reduced.
In 2008, several rounds of cold waves in the south caused a disaster of rain, snow and freezing. In 2016, the BOSS-level cold wave made Guangdong all snow. In January of this year, the cold wave caused many places in the north to set a new record for the lowest temperature since meteorological records.
Under the background of global warming, the probability of occurrence of extreme weather and climate events increases, and extreme cold wave weather is more likely to occur.
Will we experience more cold waves this winter?
On November 27, the National Climate Center officially announced that the equatorial Central and Eastern Pacific will enter the La Niña state in October 2021, and it is expected that a weak to moderate La Niña event may occur in the winter.
According to historical data, the temperature in the central and eastern regions of my country in the winter of La Niña is often low.
So, here comes the question, will we experience more cold waves next?
According to the forecast of the National Climate Center, this winter (December 2020 to February 2022) my country's temperature is generally colder, with large fluctuations in the seasonal cold and warm.
In December 2021, with the exception of low temperatures in Northeast China and eastern Inner Mongolia, most parts of the country have temperatures close to normal or high.
However, from January to February 2022, the cold air activity will become significantly stronger. The temperature in most of the central and eastern parts of my country may be lower than normal. The possibility of phased extreme cooling events is high. Northeast China, North China, eastern Northwest China, Xinjiang In the north and other places, there may be periods of strong temperature drop and heavy snowfall.
Zhou Bing, chief of the climate service of the National Climate Center, also said in an interview with the media a few days ago that at present, the center of the cold vortex in the Arctic has a tendency to lean toward the eastern hemisphere. Therefore, the number of cold waves may increase further from January to February next year.
November, with frequent cold waves, has passed, but the real cold has not yet arrived.
(Planning / Zhang Fangli Design / Ren Chengying Zhang Li Data Support / Shi Yan Hu Xiao)