The cliff is cooling down. Experts say this year will be the "Double La Nina Year". Which month is the coldest?

In the winter of 20021,the temperature in 65438+February will be higher than that in the same period of last year, and1-February will be lower, and the coldest month will most likely appear in 65438+1October in 2022.

Since1October 4, 202 1, 165438+ autumn, the strongest cold wave has been pushed from northwest to southeast and south China, and the northern region has ushered in a wide range of windy, rainy and snowy weather. At 8: 00 pm on the 6th, the Central Meteorological Observatory issued an orange warning of blizzard, and there will be snowstorms and even heavy blizzards in many places in the north.

Then the cold air will continue south. By the morning of the 7th, the cold front will reach Lingnan directly. On the evening of the 7 th, there will be cooling and rainy weather in Guangdong Province, when the highest temperature in Guangdong was still 30 degrees Celsius!

Cold wave has the characteristics of wide influence range, long duration, large cooling range and strong rain and snow weather. This cold air from the Arctic is not only related to the general trend of global warming, but also to La Nina phenomenon.

As early as June of 5438+ 10, the National Climate Center declared that since July of 20021year, the sea surface temperature in the eastern Pacific near the equator has become extremely cold, and La Ni? a phenomenon was confirmed in June of 20021year, and it is expected that China will experience a weak to moderate La Ni? a event in winter.

1, what is La Nina? La Nina means "El Nino" in Spanish, referring to a little girl, while a little boy means "El Nino" in Spanish, so we can know that La Nina is actually a climate phenomenon opposite to El Nino, so La Nina is also called anti-El Nino.

The familiar El Nino refers to the climate phenomenon that the sea surface temperature in the Pacific Ocean is warmer. So La Nina refers to the abnormal cooling of seawater in the central and eastern Pacific Ocean, which will bring different degrees of influence to the global climate.

The Pacific Ocean near the equator is affected by the southeast trade winds all the year round, and the sea water on the surface of the East Pacific Ocean is blown to the west Pacific Ocean, so the cold water below the East Pacific Ocean will turn up to make up for the scraped part, which will reduce the atmospheric temperature over the sea surface of the East Pacific Ocean. This is a normal climate phenomenon.

However, in some years, the southeast trade wind suddenly strengthened, and more sea water on the surface of the eastern Pacific was blown to the western Pacific. You should know that the sea surface temperature on these surfaces is relatively high, so the sea surface in the western Pacific will heat up, and the atmospheric temperature over this sea area will also rise abnormally.

If this situation continues to develop, a large amount of warm and humid air will accumulate over the western Pacific Ocean, eventually forming a strong typhoon or tropical storm. Therefore, in La Nina, typhoons will be stronger in summer and autumn in China.

On the other hand, more sea water has been blown away in the eastern Pacific Ocean, and more cold sea water needs to be replenished, which makes the sea surface temperature in the eastern Pacific Ocean extremely cold, and the temperature above the sea surface is lower and the air pressure is higher.

The result of higher air pressure is that the southeast wind trade winds are stronger, forming a positive cycle: the southeast wind trade winds are strengthened-the sea surface temperature in the eastern Pacific is reduced-the southeast wind trade winds are strengthened! As a result, the sea surface temperature in the East Pacific Ocean is getting colder and La Nina phenomenon is formed.

How about La Nina Twin Peaks? Actually, it means literally. We know that La Nina phenomenon appeared in 2020, that is, from July 2020 to March 20021year, and confirm that La Nina phenomenon was formed in June 20021year, that is to say, La Nina phenomenon appeared twice in 20021year, so it is called double-peak La Nina.

2. What is the influence of La Nina? With such attention, La Nina must have something extraordinary and her influence will be even greater. In the year when La Nina appears, the global climate will be abnormal, and the probability of extreme climate will increase. Just look back on several extreme weather events in China since the winter of 2020.

I. Climate In the winter of 2020, China experienced four major cold waves, with the lowest temperature extremes in many parts of the country; Followed by the sandstorm weather from March to April, there were 12 large-scale sand blowing and sandstorm weather in the north of China, which were rare in the same period in the past 50 years with high frequency and wide range.

Then there was the heavy precipitation in July, the rainstorm disaster in Zhengzhou, Henan Province, and the rainfall intensity was rare in history; During the National Day Golden Week, the temperature was unusually high in most parts of China, and the "autumn tiger" was impressive. The recent extreme climate is the first cold wave since autumn, which has a wide range of influence, a large cooling range, a long duration and strong rain and snow weather. It is a description of the characteristics of this cold wave!

Therefore, the year when La Nina phenomenon appeared had an impact on our country, that is, the climate was abnormal, it would be hotter when it was hot, it would rain harder when it rained, and it would be colder when it was cold!

3. Will La Nina bring winter? Another question that people are more concerned about is whether the winter of 202 1 will be a cold winter, especially when the cold wave strikes. People are more worried about whether the winter of 202 1 will be frozen and cried.

But what I want to say here is that La Nina and winter cannot be equated. Look at a set of data and you will understand: in the 70 years from 195 1 to now, there have been 15 La Ni? a phenomena, of which 10 La Ni? a years are cold winters and the other 5 La Ni? a years are warm winters.

In other words, the year when La Nina appears will increase the possibility of cold winter in China, but this does not mean that there will be cold winter in winter. Because the concept of cold is different from that of cold winter, cold refers to whether the average temperature is low or high, and there are strict standards for judging cold winter.

The basic factor to judge the cold winter is the average temperature of three months in winter, which is divided into three levels in space: single station, regional and national.

Single station cold winter means that the average temperature anomaly of a single station is less than or equal to -0.43 times standard deviation; Regional cold winter means that the number of cold winter stations exceeds 50% of the total number of regional stations; The national cold winter requires that the cold winter area exceed 50% of the national effective area. Therefore, the criterion for judging the cold winter is related to the degree and range of low temperature.

For example, in the winter of 2020 in China, I believe you still remember the four big cold waves, but in March of 20021,the National Meteorological Center released a message saying that the winter of 2020 is warm! The reason is that the nationwide warming weather in February 20021year suddenly raised the average temperature in the whole winter of 2020.

Therefore, under the influence of La Nina, the probability of winter cold in 202 1 will increase, and even extreme low temperatures will occur several times, but whether winter is cold or not will not be determined until the end of winter.

4.202 1 which month is the coldest in winter? It's really hard to tell which month will be the coldest. The first big cold wave since autumn can be called "winter in one day" and "the strongest cold wave", but this cold wave will not cause the extreme value of the lowest temperature in winter.

It is said that its strongest refers to the influence range and cooling range. Before the cold wave strikes, the temperature in most parts of China is high, so the cooling rate brought by the cold wave will be great.

According to the news of National Meteorological Center165438+1October 4th, meteorologists predicted the winter climate trend in 20021year, and pointed out that the cold air that affected China in the winter of 20021year was frequent and strong, the temperature in the central and eastern regions was mainly cold, and the precipitation was generally distributed in the north and south.

In addition, except for the northeast and eastern Inner Mongolia, where the temperature is low in June 5438+February, the temperature in most other parts of the country is close to the same period of the year or high, which means that the coldest month in winter in 20021year will not appear in June 5438+February.

By June 5438+0-February, 2022, the cold air activity will obviously become stronger, and the temperature in most parts of the central and eastern regions may be lower than normal, so there is a greater possibility of staged extreme cooling events, so the coldest month of this winter will appear in June 5438+0 or February, 2022.