Dialogue with the chief expert of China Meteorological Administration:
How strong is the cooling ability of the strongest cold wave this winter?
The strongest cold wave since the beginning of winter this year is coming.
According to the forecast of the Central Meteorological Observatory, it is expected that from this Saturday (November 26) to the 30th, cold weather will sweep across our country, and the temperature in most areas will plummet.
On November 25, a reporter from Chengdu Commercial Daily-Red Star News had a conversation with Ye Dianxiu, a research-level senior engineer at the National Climate Center and chief expert of meteorological services at the China Meteorological Administration, on issues related to the cold wave.
What are the criteria for a cold wave?
Speaking of cold waves, many people have memories of being dominated by them.
As the existence of the "strongest" cold air, what is its scientific definition?
In this regard, Ye Dianxiu explained that the cold wave is a kind of cold air, and it is also a kind of disastrous weather.
Ye Dianxiu told reporters that the specific criteria for judging the impact value of a cold wave are that the daily minimum temperature in a certain place drops by 8°C or more within 24 hours, or by 10°C or more within 48 hours, or by 10°C or more within 72 hours. It is equal to 12 ℃, and the cold air activity that makes the daily minimum temperature of the place ≤ 4 ℃ can be called a cold wave.
Ye Dianxiu said that there is no difference between the north and the south in the current monitoring and assessment of cold waves in meteorological operations.
Ye Dianxiu told reporters that in my country, cold waves mostly occur in late autumn, winter and early spring.
Statistics show that in the past 30 years (1991-2020), there have been an average of 5.4 cold waves per year in my country.
Ye Dianxiu recalled that since 1991, 2021 is the year with the most cold waves in my country, with a total of 11.
"Monitoring shows that the average temperature drop in each cold wave in most parts of my country is above 10°C." Ye Dianxiu said, but the temperature drop affected by the cold wave varies greatly in different regions.
Where does the cold wave affecting our country come from?
Where does the cold air affecting our country come from?
Ye Dianxiu said that the paths can be roughly divided into four paths, namely the Northwest Path, the North Path, the West Path and the Northeast Path.
Specifically, the northwest path refers to the cold air entering my country from the White Sea and the Barents Sea west of Xindi Island through Western Siberia and Mongolia; the northern path refers to the cold air entering northern Asia from the Kara Sea or the Novosibirsk Sea east of Xindi Island , entering my country from north to south through Mongolia; the western path refers to the cold air passing through the Eurasian continent south of 50°N and passing through Xinjiang from west to east to affect the eastern part of my country; the northeast path refers to the cold air from the Sea of Okhotsk or eastern Siberia to the southwest affect Northeast my country.
"Among them, cold waves entering our country through the northwest, north, and west paths are more common, while the cold waves entering our country through the northeast path are less frequent and less intense." Ye Dianxiu said.
According to Ye Dianxiu, in my country, the frequency of cold waves is more distributed in the north and less in the south.
Among them, the regions most "favored" by cold waves include Northeast China, western and northern North China, northern and central Northwest China, most of Tibet, Inner Mongolia and other places, and the average annual frequency of cold waves is more than 4 times.
So, is there a significant difference in the number of cold waves and cooling capacity between cold winter and warm winter?
Is the cold wave process in warm winter necessarily less than that in cold winter?
the answer is negative.
Ye Dianxiu told reporters: "There are obvious differences between the elements for determining cold winter and cold wave and the time period, and there is no necessary relationship between the annual cumulative frequency of cold wave and cold or warm winter.
The frequency of cold waves in cold winters may not necessarily be higher than that in warm winters.
For example, Ye Dianxiu said that in 1998 and 2019, these two years were both strong and warm winters, but the number of cold waves reached 6 times, which was stronger than the previous cold winter periods, such as 1983 (3 times), 1984 (2 times), 1985 (2 times) and other periods had significantly more cold waves.
Chengdu Commercial Daily-Red Star News reporter Yang Yuqi Zhang Yanliang