"There's a little air in the sand" "This scene feels like you've traveled through"...

Early yesterday morning, "sandstorms" and "eating soil" both rushed to the hot search - in fact, they are all the same thing: affected by cold air and Mongolian cyclones, the fifth round of sand and dust weather since March is currently affecting the northern region of China, and even a few southern regions.

The number of dust processes in the same period of the year is about 5-6 times, and this is the eighth dust weather process in China since this year. Since April 8, this round of dust weather has reached the level of a dust storm, the second sandstorm process this year. The Central Meteorological Observatory issued a blue warning for sandstorms at 4:9 on the 8th, and continued to issue a blue warning for sandstorms at 18 o'clock yesterday. Meteorological satellite monitoring shows that the peak concentration of sunshine PM6 in Shandong even reached 10 micrograms / cubic meter.

The Central Meteorological Observatory predicts that later this month, there will also be sand and dust weather affecting China, from the 13th to the 16th, the northwest region and North China and other places are still sandy and dusty, of which, from the night of the 13th to the 14th, the sand and dust weather may again affect Beijing-Tianjin-Hebei and other places.

Why is dust so frequent this year

Sand and dust weather refers to the weather phenomenon in which the wind swept dust and sand particles into the air, making the air turbid. The formation of sand and dust weather requires long-lasting strong winds as power, sand and dust sources, and also requires instability in the lower atmosphere, which is conducive to the development of strong convection and carries more sand and dust higher.

Yesterday, Gui Hailin, chief forecaster of the Central Meteorological Observatory, was interviewed by reporters to interpret the situation related to the sand and dust weather.

"From the perspective of dust sources, this year's dust weather is basically caused by the strong winds brought by the Mongolian cyclone. When the sand and dust pass through China, there is a supplement of sand and dust along the way in the arid and semi-arid areas of northern China, so the source of sand and dust is actually a common role of Mongolia and China. Gui Hailin said.

Wu Bo, director of the Institute of Desertification of the Chinese Academy of Forestry, analyzed that the main domestic sources of sandstorms in China are concentrated in desert areas such as southern Xinjiang, Gansu Hexi Corridor, and central and western Inner Mongolia, and vegetation restoration in these areas has played a certain role in reducing the amount of dust released in sand source areas and reducing the harm of sandstorms. However, the Gobi Desert in southern Mongolia is also an important source of sand and dust affecting China, and the vegetation growth in southern Mongolia in 2022 is deviated from the average in recent years, and the vegetation cover of the sand and dust source is poor.

"During this period, Mongolia and northern China have less precipitation, and the temperature in the early spring has warmed up significantly, resulting in the melting of the permafrost and loose surface sand, coupled with the high incidence of winds in the northern region in spring, combined with the surface conditions of exposed sand and dust sources, forming frequent sand and dust weather." Wu Bo said.

According to experts, the main causes of the occurrence of sand and dust weather are: first, China's cold air activity is still in an active period, and the wind generated by the Mongolian cyclone and the ground cold front is large, which provides the power conditions for the occurrence of sand and dust weather; Second, the temperature rises rapidly in the early stage, and the unstable air state provides thermal conditions for sand up. Third, the precipitation in Mongolia and China in the early stage of sand and dust source areas is low, the soil moisture is biased, and the current vegetation has not yet turned green, and the surface is exposed, which is not conducive to suppressing the occurrence of sand and dust weather.

Whether China has entered a period of active sand and dust

Gui Hailin said that since the 9th, China's sandstorm weather process has reached the level of sandstorm, which is the second sandstorm process this year. The sand and dust weather process has a large impact area, and sandstorms have occurred in many places in China.

On the 11th, as the cold air moved eastward to the south, the dust weather continued to advance south. Gui Hailin said that as of 11 a.m. on the 7th, the impact area of this round of sand and dust weather in China has reached more than 360.390 million square kilometers, and as the cold air continues to move south, it is expected that the impact area of this round of sand and dust weather in China will reach 400 to 4 million square kilometers, affecting about 09 million people.

Since 2018, the average total number of sand and dust storms in northern China has been higher than the average value in 2013~2017, showing a slight increase.

"As for whether to enter the active period of sand and dust, it needs to be looked at from a larger time scale. Since 2000, the number of large-scale sand and dust in China has been decreasing or decreasing overall, but in recent years, especially in some years, the number of sand and dust is slightly more than the same period of the year, which is related to many factors, such as surface vegetation, precipitation, temperature, snow cover, and the intensity of the weather system, etc., these factors will have inter-annual changes. Therefore, on the whole, from the current situation, it cannot be judged that China has entered a new active cycle of sand and dust. ”

Ding Ting, a researcher at the Climate Prediction Office of the National Climate Center, said that between 2018 and 2022, the total average number of sand and dust storms in northern China was higher than the average from 2013 to 2017. However, from a longer time scale, in the first 21 years of the 10st century, the total number of dust and the number of dust storms are significantly higher than in the past 10 years. This shows that at this stage, China is still in the context of reducing the impact of sand and dust, and it cannot be considered that there is a significant trend of sandstorms.

Is "crossing the Yangtze River to the south" common?

Is it a common phenomenon that this round of sand and dust crossed the Yangtze River and affected the south?

Gui Hailin said that according to the forecast range, the overall impact of the sand and dust weather is mainly in the north of the Yangtze River, and the areas south of the Yangtze River, such as northern Zhejiang and northern Hunan, may be affected a little, but the impact is not large. As for the reason for the sand and dust to go south, when a weather system in the north is very strong, the sand and dust outbreak location is just in the main sand source, the sand and dust intensity will be relatively large, and under the transportation of the northerly air flow at high altitude, it can often reach a long-distance transportation.

"In fact, not only to the south, from the monitoring data, in the relatively strong dust weather, you can even circle the earth, and some sand and dust from the Asian region have also been detected in the European Alps." Therefore, sand and dust is a long-distance transportation phenomenon, even if it affects the southern region of China, it is not a particularly rare thing. Gui Hailin said.

In addition, he also said that if the public pays attention to the impact of sand and dust on China for a long time, it is not difficult to find that every stronger sandstorm process will basically affect Huanghuai, and even cross the Yangtze River to Hunan, Jiangxi, Zhejiang and other regions. The scope of influence also depends on the path of the sand, if the path is westward, sometimes it will cross from the Gansu Shaanxi side, and the intensity will even reach the Sichuan Basin.

Gui Hailin said that sandstorms usually bring some impact on transportation, agriculture and animal husbandry and human health, for example, dust particles will carry some heavy metals or sensitive sources along the way, so people with cardiovascular or allergic constitution should go out as little as possible during the sand and dust, or go out to do a good job of protective measures, such as wearing masks, scarves, etc. In addition, sand and dust are usually accompanied by windy weather, need to pay attention to the reinforcement of outdoor structures or billboards, outdoor high-altitude work should strengthen personal safety protection, pedestrians as far away as possible from high-rise buildings, to avoid being hit by blowing objects. For agriculture and animal husbandry, sand and dust will cause wind erosion and desertification of the land, and the protection of farmland should be strengthened.

Not all dust is called a sandstorm

Whenever the sky turns yellow and dust floats in the air, some people think: a sandstorm is coming! In fact, not all dust weather is a dust storm. Only when the dust weather reaches a certain intensity can it be called a dust storm. In meteorology, according to the impact from light to heavy, sand and dust weather can be divided into floating dust, blowing sand, sandstorm, strong sandstorm and extra strong sandstorm.

Sandstorms, especially particularly strong ones, are extremely harmful and disastrous weather. When a dust storm hits, the meteorological department issues a corresponding warning. According to the current national warning release standards, the sandstorm warning issued by the Central Meteorological Observatory is divided into three levels: sandstorm blue, yellow, orange warning, the warning color from light to dark, representing the degree of impact and defense level is getting higher and higher.

"In fact, sand and dust are not weather that needs to be cured, and in addition to some adverse effects, there are also some benefits to the global ecosystem." Gui Hailin emphasized.

He said that for some climate zones with scarce precipitation, we are now adopting a scientific attitude to sand prevention and control, that is, to make sand and sand in these areas, mainly to prevent the expansion of other sandy areas. "In places that are not conducive to vegetation growth, with this kind of windy cyclone weather system, sand and dust are an inevitable weather phenomenon, so it is not a weather that needs to be cured."

"And sandstorms are actually an international phenomenon, and governance requires international cooperation." Not only in China, but also in Uzbekistan and Kazakhstan in Central Asia, but also in the Gobi Desert in southern Mongolia, a wide range of sand sources also need to effectively control sand and dust. Gui Hailin said.

Experts said that desertification control is not achieved overnight, and in the future, it is still necessary to strengthen vegetation restoration, reduce the frequency of dust weather and dust storm hazards, and strengthen international cooperation to jointly control the global problem of dust storm damage.

Comprehensive Xinhua News Agency, CCTV, China News Agency, China Weather Network reports