From April 4 to 9, a large-scale sand and dust weather occurred in China, and Inner Mongolia, Beijing, Hebei and other places reached the level of sandstorms, which is the eighth sand and dust weather process encountered by China since the beginning of this year, and the second large-scale sandstorm process. How much land area does this sand and dust process cover? How long will the dust last? Will there be widespread dust weather in the future? The Beijing News reporter interviewed a number of experts about this.

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Affected by southerly winds, sand and dust may return to Beijing

Beijing News Affected by the Mongolian cyclone and cold air, Beijing has had sand and dust weather since April 4. At 10 o'clock on the 10th, the PM20 concentration increased sharply from 10 micrograms / cubic meter to 1 micrograms / cubic meter in one hour, reaching a level 400 serious pollution level, and a peak concentration of 1321 micrograms / cubic meter appeared at 6 o'clock, and by 22 am on the 1384th, the PM11 hour concentration was 8 micrograms / cubic meter, maintaining a serious pollution level.

On April 4, the minimum visibility in most parts of Beijing was less than one kilometer, and local gusts reached 11. In the afternoon, as the sand and dust moved out of Beijing, the Beijing Meteorological Bureau announced at 10:15 that the visibility of Beijing had improved significantly, and the yellow warning signal for sandstorms was lifted.

However, the Beijing Meteorological Observatory reminded that there was a southerly wind during the day on April 4, with gusts of about 12 degrees, so there was a risk of sand and dust backflow. In other words, under the action of the south wind, the sand and dust that has gone south may kill a "horse gun" and return to Beijing again.

The reporter learned that the intensity of reflux sand and dust will not be too strong, because part of the main body of sand and dust has already gone south, and the intensity of reflux will be weaker than the first time. It should be noted that although the concentration of sand and dust returning is lower than that of the first round, it is still necessary to take protection and wear a mask when going out.

From the second half of the night on Thursday, a new wave of cold air will arrive again with a north wind, and it will blow again on Friday and Saturday, as well as the possibility of sand and dust, which is currently expected to be weaker than this process.

1 What is the impact of this sand-and-dust weather?

On April 4, the reporter learned from the State Forestry and Grassland Administration that from April 11 to 4, a large-scale sand and dust weather occurred in China, Inner Mongolia, Ningxia, northern Shaanxi, northern Shanxi, northern Hebei, southern Heilongjiang, Jilin, north-central Liaoning, southern Xinjiang basin, Beijing and other places appeared sandstorms or floating dust weather, Inner Mongolia Hohhot, Baotou, Hebei Zhangjiakou, Beijing and other local areas appeared sandstorms or strong sandstorms. As of 9 o'clock on the 11th, it mainly affected 11 counties (cities, districts and banners) in 8 provinces (autonomous regions and municipalities directly under the central government), covering an area of about 15.902 million square kilometers and a population of about 229 million people.

"On April 4, under the influence of cold air continuing to move south, sand and dust will also appear in Hubei, Anhui, Jiangsu and other places. Overall, the estimated impact is between 11.390 million and 400 million square kilometres. Gui Hailin, chief forecaster of the Central Meteorological Observatory, said that this is the eighth large-scale sand and dust weather in China since this year, and the fifth sand and dust weather since March.

2 When will this dust weather end?

At 4 o'clock on April 11, the Central Meteorological Observatory continued to issue a blue warning for sandstorms: affected by cold air and winds, it is expected that from 18:4 on April 11 to 20:12 on April 20, there will be sand or floating dust in parts of eastern and southern Xinjiang basins, central and western Inner Mongolia, eastern Gansu, Qinghai Qaidam Basin, Ningxia, north-central Shaanxi, Shanxi, Hebei, Beijing, Tianjin, southern Heilongjiang, Jilin, Liaoning, Shandong, Henan, north-central Anhui, Jiangsu, Shanghai, central and eastern Hubei and other places.

Gui Hailin told reporters on the 11th that the sand and dust will weaken from the night of April 4 to the end of 11. Another sand and dust is expected this week, which may affect the Beijing-Tianjin-Hebei region.

"On the afternoon of April 4, the sand and dust weather will affect some areas north of the Yangtze River, such as Jiangsu, Anhui, Hubei, and even northern Zhejiang and northern Hunan. There may be some remnants of the sand and dust weather on the 11th, but overall, from the night of the 12th to the 11th, it gradually weakened and ended. Gui Hailin said.

3 Will there be more dust in the coming days?

Spring dust weather is frequent, will there be dust weather after that? Gui Hailin introduced that from the current data research, it is expected that from April 4 to 13, there will still be more cold air and dust activity in northern China, "Among them, from the night of the 16th to the day of the 13th, the northwest region and northern China will be affected by sand and dust, and there may also be sand and dust weather in Beijing-Tianjin-Hebei, and Beijing may have some sand blowing, and the intensity is expected to be weaker than this time." ”

Gui Hailin introduced that this sand and dust weather is not the most serious this year, from March 3 to 19, China experienced a "strong sandstorm" level of sand and dust weather, the current process only reached the "sandstorm" level, so in terms of intensity, it is not the strongest this year.

4 Is it rare for sand and dust to "blow" to the south?

Gui Hailin said that the overall impact area of the sand and dust is mainly north of the Yangtze River, and northern Zhejiang and northern Hunan south of the Yangtze River may be affected a little.

Why does the sand and dust "blow" to the south? Gui Hailin told reporters that sand and dust are weather phenomena transported over long distances. If the weather system in the north is very strong, and the location of the outbreak is in the main source of sand, the intensity of the dust weather formed will be relatively strong. At the same time, under the action of the northerly air flow at high altitude, sand and dust can often reach long-distance transportation. In several sand and dust weather since March this year, basically reaching the level of "sandstorm", or even "blowing sand", the sand and dust weather will affect the Jiangbei area. "For example, the two sandy weather days from March 3 to 3 and March 9 to 10 affected Suwan and Anhui provinces."

"Every strong sandstorm process will basically affect Huanghuai, and even cross the Yangtze River, affecting Hunan, Jiangxi, Zhejiang and other regions. The area of influence also depends on the path of the sand, if the path is westward, sometimes across the Qinling Mountains and even to the Sichuan Basin. Therefore, even if the sand and dust affect the southern region of our country, it is not a particularly rare thing. Gui Hailin also introduced that from the monitoring data, when the sand and dust are relatively strong, it can even circle the earth, and dust particles from Asia have also been detected in the European Alps.

5 Has the sand and dust weather in Beijing increased this year?

This is the fourth sand and dust weather that Beijing has encountered this year. Compared with previous years, has the sand and dust weather in Beijing increased this year?

Qiu Qihong, chief forecaster and senior engineer of the Beijing Ecological Environment Monitoring Center, said that from the air quality monitoring data of Beijing sand and dust weather from 2000 to 2022, from 2000 to 2002, Beijing suffered from severe sand and dust weather for three consecutive years, and the sand and dust weather weakened year by year from 3 to 2003. In 2005, there was another severe sand and dust weather, and since then, the sand and dust weather has generally shown a trend of weakening year by year. In the past two years, the dust weather has rebounded, especially this spring, showing a frequent trend.

Around 2001, the influence of sand and dust on the annual average concentration of PM10 was detected to be about 10%, and then the fluctuation decreased, and it was only 2013% in 2. From 2013 to 2020, the impact of sand and dust on the annual average concentration of PM10 was 2%-8%, which was relatively stable, but it rebounded in the past two years, and the contribution of sand and dust in 2021 was 15 micrograms / cubic meter, accounting for 10% of the annual average concentration of PM22.

6 Where does the sand and dust affecting Beijing mainly come from?

According to the WeChat public account information of the Beijing Municipal Ecology and Environment Bureau, the sand and dust weather in Beijing is mainly caused by the transmission of foreign sand and dust. In recent years, the desertification trend in Mongolia has intensified, and the desertification land in the arid and semi-arid areas of northwest China has provided sufficient sources of sand and dust for the occurrence of sand and dust weather. The source of Beijing's dusty weather is mainly the Gobi Desert in south-central Mongolia and the desert in central and western Inner Mongolia, in addition to the Hunshan Dak Sandy Land in the east of Inner Mongolia near northern Hebei and the Horqin Sandy Land in the northeast.

Qiu Qihong introduced that the generation of dust weather must meet three conditions at the same time: one is the sand source area, the other is the lifting movement, and the third is the transmission effect of strong winds. This spring's sand and dust are more because three conditions are met at the same time. Since last winter, Mongolia has received less precipitation than the same period of the year, and the vegetation cover in the sand source area is poor. In the early spring of this year, the temperature in the arid and semi-arid areas of Mongolia and northwest China was high, the surface thawed early, the sand of the permafrost layer melted rapidly, the surface soil was dry and loose, and the vegetation had not yet grown. Since March, Mongolian cyclones have developed strongly, and the temperature has warmed up significantly, and there has been a relatively rare warming weather. Especially after entering mid-March, the south-central part of Mongolia to the vast area of Inner Mongolia encountered more frequent cyclone and frontal system activities. Mongolian cyclones and winds are the "porters" of sand and dust, and under strong wind conditions, sand and dust have been transported to China many times, which is the most direct cause of sand and dust weather in northern China this spring.

7 China has entered an active cycle of dust weather?

Recently frequent sand and dust, does this mean that China has entered an active cycle of sand and dust weather?

Gui Hailin introduced that from recent years, the number of sand and dust in some years is slightly higher than the same period of the year, for example, from 2018 to 2022, the average number of sand and dust storms in northern China is more than the average number from 2013 to 2017. However, from a larger time scale, from 2000 to the present, the number of sandstorms and dust weather in China has shown an overall trend of reduction.

Gui Hailin said that from March to May every year, it is the high season of sand and dust weather in China, and the occurrence of sand and dust is related to many factors, such as surface vegetation, snow, temperature, precipitation, and most importantly, the strength of the weather system. "There will be some inter-annual variations in the intensity of the weather system, which will lead to fluctuations in the number of dust weather in our country. In general, from the current data, it does not mean that China has entered an active cycle of sand and dust weather. ”

8 Can dust weather be cured?

For the prevention and control of sand and dust weather, Gui Hailin suggested that the public should look at it with a scientific attitude, in areas with dry climate and little vegetation, sand and dust in case of strong winds is a normal weather phenomenon, and there is no need to "eradicate" sand and dust weather.

He added that sand and dust weather will bring adverse effects on traffic and human health, and we must pay attention to protection. At the same time, we must also see that where dust weather is beneficial to the global ecosystem, dust weather will play a regulating role and is an indispensable part of the natural ecosystem.

Gui Hailin also said that China's three north shelter forests have played a great role in suppressing sand and dust, and from the monitoring of recent years, the probability of sand in the source of sand has been greatly reduced. "When sand and dust are frequent, the role of China's ecological shelter forests cannot be denied."

In addition, sandstorms are an "international" phenomenon, which is cross-border, and it requires not only governance in our country, but also international cooperation. "Because there are not only sand sources in China, including Uzbekistan and Kazakhstan in Central Asia, and the Gobi Desert in southern Mongolia, these are widely distributed sand sources." Therefore, in order to effectively control sand and dust, in addition to some measures taken by China in ecological governance, we must also carry out international cooperation with neighboring countries to jointly strengthen the governance of ecological civilization. Gui Hailin said.

A04-A05 Edition Writing/Beijing News Reporter Wang Jingxi, Zhang Lu, Zhang Jianlin