Where are the main sources of sandstorms in our country?

Due to its unique geographical environment, the northwest region of China is an area where sandstorms frequently occur, and the main sources include the Gurbantunggut Desert, the Taklamakan Desert, the Badain Jaran Desert, the Tengger Desert, the Ulan Buhe Desert and the Mu Us Desert.

The sources of sand and dust weather affecting China can be divided into two types: overseas and domestic. The analysis shows that two-thirds of the dust weather originates in the southern part of Mongolia and is strengthened by the replenishment of dust materials when passing through the northern part of China. The source of sand in the territory is only about one-third.

The dust weather in Central Asia (Kazakhstan) is unlikely to affect the eastern part of Northwest China and even North China. The Taklamakan Desert in southern Xinjiang is a high-incidence area of sand and dust weather in China, but it generally does not affect the eastern part of Northwest China and North China. The dust weather path in China can be divided into northwest path, westerly path and northerly path

Northwest 1 path, sand and dust weather generally originates in the central and western parts of the Mongolian Plateau or the Alxa Plateau in western Inner Mongolia, mainly affecting northwest China and North China; Northwest 2 path, sand and dust weather originated in southern Mongolia or central and western Inner Mongolia, mainly affecting the eastern part of Northwest China, northern North China, and most of Northeast China. In the westerly path, the dust weather originated in the Gobi region in the southwest or south of Mongolia and the desert area in the western part of Inner Mongolia, and mainly affected the northwest and north China of China. In the northerly path, sand and dust weather generally originates in the vast area south of Ulaanbaatar in Mongolia, and mainly affects the eastern part of Northwest China, most of North China and the southern part of Northeast China.

In recent years, there has been an upward trend of sand and dust weather in northern China in spring, which has brought many adverse impacts on people's work, life, transportation and environmental management.

1. Time: The occurrence time of sandstorms in China is mainly from March to April. Taking 2002 as an example, there were 12 sand and dust processes in the country, including 4 strong sand and dust storm processes, all of which occurred in March and April, and the National Satellite Meteorological Center monitored and analyzed all the above processes.

2. Region: The main area of sandstorm occurrence is 110 degrees to 117 degrees east longitude and 38 degrees north latitude, that is, Cangzhou, Hebei Province as the boundary, north to Tianjin, Beijing to Inner Mongolia, west through Shijiazhuang, Yinchuan, Lanzhou, Qinghai Qilian, and north to the border of Inner Mongolia.

3. Source: The main source of sandstorms in China is Mongolia and even the desert areas of Central Asia, and the intensity of such sandstorms is large, and its impact is significantly greater than that of sandstorms in the domestic source areas. The source areas in China are the Hexi Corridor of Gansu, the southern part of Inner Mongolia, the northern part of Hebei and other desert areas.

4. Path: In recent years, especially last spring, there are four main paths of sandstorms affecting Beijing: one is the Mongolia-Inner Mongolia-Beijing northeast path.

The second is the eastward movement of the Hexi Corridor to Beijing. The third is to influence Beijing from the Zhurihe region of Inner Mongolia through the Zhangjiakou area of Hebei Province. The fourth is to affect the Beijing area from the northern Shanxi Plateau to the east.

5. Related factors: Through the preliminary analysis of the main dust processes and related climatic factors in Huahua area since 1998, especially in 2002, namely ground vegetation, snow cover in February, soil moisture of 0-10 cm, and air temperature, it is believed that the dust weather is closely related to the cold air activity in spring, and when the cold air path in spring is westward and southerly, such as April 1999, there is less sand and dust weather in North China, and the main process occurs in Northwest China. On the contrary, when the main force of cold air is easterly and northerly, such as April 2000 and March 2002, the main process occurs in North China.

6. The impact of sandstorms: strong sandstorms not only affect the northwest, north, central and east China, but also can be transported to the northeast if they encounter high-altitude jet stream areas at an altitude of 7-8 kilometers and under the situation of strong development of the cold air vortex in the northeast, affecting the northeast, the far east, and even further north, which is caused by the global atmospheric circulation.

It occurs mainly in the northern regions.

Inner Mongolia, Beijing, Xinjiang, Gansu and other places.

The average number of dust days from 1981 to 2010 was 12 days (1954), and the maximum number of days since 2000 was 9 days, which occurred in 2001. The most recent dust storm occurred on April 15, 2015. On March 18, 2020, there was a blowing sand.

How to protect against sandstorms?

Stay indoors with closed doors and windows, especially the elderly, infants, and people with respiratory allergic diseases who have poor immunity.

If you must be outdoors due to necessity, try to avoid cycling, use wet towels and gauze to protect your eyes and mouth, and wear dustproof clothing, gloves, face masks, glasses and other items.

If you're outside, stay away from trees and billboards, crouch against a sturdy low wall that shelters from wind and sand, lie on a leeward side of a relatively high slope, or hold on to a solid object.

Chronic cough with sputum or shortness of breath, episodic wheezing, and chest pain should prompt medical attention.

Three conditions need to be met for the formation of sandstorms, namely strong winds, sand and dust sources, and unstable air conditions. Zhang Bihui said that the cause of the sand and dust is mainly affected by two factors, one is affected by the underlying surface conditions, and the thermal conditions are good. In the early stage, the temperature in Mongolia and the northwest of China was obviously high, the precipitation was less, the surface gradually thawed, and the dust particles were easy to sand.

Second, under the influence of the strong Mongolian cyclone, the dynamic conditions are sufficient. Wind gusts of magnitude 9-11 have appeared in northern Xinjiang, central and western Gansu, Inner Mongolia, and even northern China, providing very good dynamic conditions for the occurrence of this dust weather.

In 413 A.D., when Helian Bobo, a descendant of the Xiongnu, came to the Jingbian area of Shaanxi today, what he saw was a place full of water and grass, "shining and clear streams" of cattle and sheep, and the hero of the Sixteen Kingdoms period couldn't help but praise and said

I have traveled a lot......The beauty of Joss has not been seen. ”

In order to ensure the quality of the construction of the project, every time a small section of the city wall was built, Helian Bobo's men would let the archers fire arrows at a certain distance against the city wall, and if the arrow penetrated the city wall by an inch, then all the laborers who built this section of the city wall would be killed, and then the corpses would be thrown into the city wall as a building material.

Helian Bobo's standard is that only when the bow and arrow hit the city wall and hit the ground, that section of the city wall can be considered successful.

Five years later (418 years), this is known as the "Tongwan City" of the Xiongnu capital city was finally completed, at that time, the secretary of the Great Xia State Hu Yizhou wrote an article praising the city, saying that the city is surrounded by "Shiguo Tianchi, Zhou Mianqian", and the city is "Hualin Lingnuma, Chongtai Secret Room, Tongfang Liange, Chidao Garden".

But this is Helian Bobo meaning "unify the world, live in the city of Wanjun", and failed to protect the Huns for long, Tongwan City was built only 9 years later (427 years) was broken by the Northern Wei army, after hundreds of years, this city after several wars, to the Tang Dynasty, once abundant water and grass Tongwan City, after hundreds of years of human development and destruction, the surrounding Mu Us sandy land is gradually taking shape, at this time the surrounding is "all quicksand", "wind and sand full of eyes", "vast desert, gradually far away Helian City".

To Song Taizong Chunhua five years (994 years), the Song army finally captured Tongwan City after repeated battles with the Western Xia, in order to prevent the Western Xia from fighting again, Song Taizong ordered the army to destroy the Tongwan City, for the deterioration of the surrounding ecological environment of the Tongwan City (then called Xiazhou), Song Taizong once said:

Xia Zhou is deep in the desert".

From its construction in 418 A.D. to its "deep desert" in 994, Tongwancheng has only experienced 500 years before becoming a "classic" of human development and destruction.

The ruins of Tongwan City.

But the Chinese' encounter with quicksand has only just begun.

Just when Tongwancheng was mired in quicksand, the Northern Song Empire also began to be troubled by the attack of sandstorms.

Just 13 years after his father Song Taizong ordered the destruction of Tongwan City, in March of the fourth year of Jingde of Song Zhenzong (1007), Kaifeng, the capital of the Northern Song Dynasty, was attacked by a huge sandstorm. ”

At that time, this huge sandstorm from today's Beijing Daimyo to Kaifeng, Henan Province and Miyang (Tang Prefecture of the Song Dynasty) made Song Zhenzong distressed. During the 167 years of the founding of the Northern Song Dynasty, the sandstorms that swept the capital Kaifeng in the later 100 years were recorded as many as 13, at that time, these sandstorms mainly from the northwest not only affected Kaifeng, but even Jiangshan County, Zhejiang, far away in the south of the Yangtze River, could feel the power of these sandstorms, so that the Northern Song Dynasty in the south of the Yangtze River was called "yellow sandfall".

Sandstorms in different periods have different origins. As far as the latest sandstorm is concerned, according to the comprehensive assessment of satellite imagery and ground monitoring information from the Desertification Monitoring Center of the National Forestry and Grassland Administration, the sandstorm mainly originated in Mongolia.

Experts point out that three basic conditions are required for the formation of dust in general: the source of sand and dust, high winds, and unstable atmospheric stratification. The source of sand and dust is the material condition; Gale is the source of power; Unstable atmospheric stratification is a thermal condition.

According to the comprehensive assessment of satellite images and ground monitoring information from the Desertification Monitoring Center of the National Forestry and Grassland Administration, the dust weather mainly originated in Mongolia. On the morning of March 14, 2021, a sandstorm occurred in the southwest of Mongolia, and the dust moved southward with the airflow, and on the evening of March 14, it entered the border between Mongolia and the central and western parts of Inner Mongolia. Sandstorms have occurred in Inner Mongolia and other places in Yannaoer, Erenhot, Baotou and other places, with visibility below 1,000 meters, and the air quality level is seriously polluted.

In the early morning of the 15th, sand and dust began to affect the Beijing-Tianjin-Hebei region, and Beijing was affected by the upstream sand and dust transmission superimposed by the wind and sand, and the PM10 concentration increased significantly, and the air quality was seriously polluted.

According to meteorological experts, the temperature in northern China has been high since March, and the meteorological conditions are generally conducive to the generation of sand and dust weather. Due to the strong development of the Mongolian cyclone (the central pressure reached 980 hPa at 2 o'clock on the 15th), the sand and dust moved eastward and southward with the cold high pressure at the back of the cyclone, affecting most of the northern part of China.

For the public in areas affected by sand and dust weather, experts remind the elderly, children and people with respiratory allergic diseases to try not to go outdoors; The public is requested to wear masks, scarves and other dust-proof supplies when going out, and wash their faces and nasal passages when they return from going out.

In addition, experts reminded that on the 15th, the north wind was strong in many places in the north, and the weather was dry and dry, so it was necessary to pay attention to wind and fire prevention; Pay attention to the reinforcement of outdoor structures and billboards, and pay attention to safety protection for outdoor high-altitude work.

The causes of sandstorms are the main reasons for the formation of sandstorms or strong sandstorms, which are conducive to the weather situation of strong winds or strong winds, and the favorable distribution of sand and dust sources and favorable air instability conditions. Strong wind is the driving force of sandstorms, and the sources of sand and dust are the material basis of sandstorms, and unstable thermal conditions are conducive to the increase of wind and the development of strong convection, so as to entrain more sand and dust and roll higher.

In addition, the drought and lack of rain in the early stage, the warming weather and the rising temperature are the special weather background formed by sandstorms. The development of convective cells in front of the surface cold front into clouds or squall lines is a small and medium-scale system that is conducive to the development and strengthening of sand and dust storms. The topographic conditions that are conducive to the increase of wind speed, i.e., the narrow tube action, are one of the favorable conditions for the formation of sandstorms.

Sandstorms in China mostly occur in Northwest China and North China.

In Northwest China, sandstorms are mainly concentrated in the surrounding areas of the Tarim Basin, the Alxa Plateau of Inner Mongolia and the Hetao Plain.

In North China, sandstorms are mainly concentrated in North China, Chifeng and Zhangjiakou.

Extended information: Sandstorm is a general term for sandstorms and dust storms, which are a sign of desertification. It refers to a disastrous weather phenomenon in which strong winds roll up a large amount of sand and dust from the ground, making the horizontal visibility less than 1 km, and having the characteristics of suddenness and short duration.

Among them, sandstorm refers to the sandstorm formed by strong winds blowing a large amount of sand into the near formation; A dust storm is a storm formed by high winds that sweep large amounts of dust and other fine particles into the air.

Morphological characteristics of sandstorms:

1. The wind and sand wall is towering.

Most of the severe sandstorms on the mainland moved from the northwest or west, and a few from the east. When almost all sandstorms come, we can see black walls of wind and sand moving rapidly in the direction of the wind, getting closer and closer. From a distance, the wind and sand wall is as tall as a mountain, very much like a city wall, and it is the vanguard of the arrival of the sandstorm.

2. It's dark.

When a strong sandstorm occurs, the wind is very strong due to the wind blowing above level 8, which can roll up stones and sand. As more and more sand and dust flew into the air, the dense sand and dust covered the sky, blocking the sun and making it impossible to see anything for a while, as if it were at night.

3. Tumbling and rushing.

When the black wind blows, the air near the ground is very unstable, and the heated air below rises, and the surrounding air flows to replenish, so that the air carries a large amount of sand and dust and rolls up and down, forming countless dust balls of different sizes that meet and rush in the air.

4. Ambilight.

The upper layer of the aeolian sand wall is often yellow to red, the middle layer is grayish-black, and the lower layer is black. The yellowing and redness of the upper layer is due to the fact that the dust in the upper layer is thin and fine-grained, and the sunlight can almost pass through the dust and shoot down. The lower layer of sand and dust has a large concentration and coarse particles, and the sunlight is almost completely absorbed or scattered by the sand and dust, so it is black.

Where the wind and sand walls moved, the sky was changing from light to dark. This is due to the fact that the light does not pass through thick and thin.

1. Caused by the sand and dust belt when it is dense and inconsistent.