How fierce is this sandstorm?

On May 4th, it was reported that strong sandstorm weather was coming! On the 4th, many places in northern China were "captured" by sandstorms, and "strong sandstorms" with low visibility appeared in other places. The Central Meteorological Observatory continued to issue a blue warning of sandstorms on the evening of the 4th.

According to meteorological monitoring, the sandstorm weather that started on May 3rd covered a wide range, covering Xinjiang, Gansu, Ningxia, Shaanxi, Inner Mongolia, Shanxi, Hebei, Beijing, Tianjin, Liaoning, Jilin, Heilongjiang, etc. 10 Yu Sheng (area, city), with an affected area of1630,000 square kilometers. In addition, the dust intensity is high, and the air quality in many places is broken. The peak concentration of PM 10 in Inner Mongolia exceeded 2000 μ g/m3, and that in Beijing exceeded 1000 μ g/m3. There are 5-7 winds in Inner Mongolia and the eastern part of Northwest China, northern North China and most parts of Northeast China, and gusts can reach 8-9.

Why did this sandstorm come so violently?

Where did this menacing sandstorm come from? Why did you come so hard? When will the dusty weather end?

Zhang, a senior engineer at the Environmental Meteorological Center of the Central Meteorological Observatory, analyzed that the dusty weather was mainly affected by cyclones and strong winds on the ground caused by the superposition of two cold air. In addition, the early temperature in the sand source area of Inner Mongolia is generally high and the precipitation is less. The superposition of these conditions promotes the formation of sand-lifting conditions.

He said that windy weather occurred in China from Mongolia to Inner Mongolia, and dust spread from Mongolia to China. However, in the process of communication, the domestic sand sources in China also contributed some sand sources.

Many people think that sandstorms are rare in recent years. Has the dusty weather decreased in northern China?

Zhang said that compared with the same period in history, this year's dusty weather was less frequent and weak. This is the seventh sandstorm weather process this year, with an average of 8.4 times in the same period in the past decade. In addition, in previous years, at this time in May, there will be more than two sandstorm weather processes. This sandstorm is the first sandstorm weather this year, which appears less and later.

"There are two main reasons for the decrease of sandstorm weather in China," he said. On the one hand, affected by climate change, the overall cold air affecting China has weakened and decreased; On the other hand, in recent years, China has done a lot of windbreak and sand fixation work, including the Three-North Shelterbelt, which has improved the sand-raising conditions in the sand source area and is not conducive to the formation of dusty weather.

He said that at the same time, we should also see that the role of shelterbelts is mainly to change the sand-forming mechanism in the sand source area, but shelterbelts can only have some local impact on the wind. "The dust that affected Beijing this time was basically transported at a height of 5,000 meters." In this case, the impact of shelter forest on wind field can be ignored.

On the evening of the 4th, the Central Meteorological Observatory continued to issue a blue warning of sandstorms: it is estimated that there will be 4-6 winds and 8-9 gusts in most parts of the north from the night of the 4th to the 5th, among which the local gust winds in central and eastern Inner Mongolia, northern North China and western Northeast China can reach 10. Sand blowing or floating dust weather will also continue in Beijing and other places, including sandstorms in parts of central and eastern Inner Mongolia.

Dust comes with the strong wind and goes away with it. Zhang said that from the analysis of current meteorological conditions, it is predicted that the impact of dusty weather on Beijing will gradually end by the evening of the 5th.

The forecast issued by China National Environmental Monitoring Center shows that the areas mainly affected by dust are gradually moving southward due to the strong north wind. From the 6th, the dusty weather in North China will gradually end. However, due to the influence of dust transport, some areas in the south may have short-term moderate to severe pollution on June 6-7.

In the face of sandstorm, we should take preventive measures.

The Central Meteorological Observatory suggested that defensive measures should be taken in the face of sandstorms. First of all, we must prepare for wind and sand prevention and close the doors and windows in time; At the same time, pay attention to carrying dust-proof articles such as masks and scarves to avoid dust damage to eyes and respiratory tract; Attention should be paid to the sealing of precision instruments. For structures that are easily blown by the wind, such as hoardings, scaffolding, temporary structures, etc. Special attention should be paid to fastening and properly arranging outdoor items that are easily affected by sandstorms.

Due to the low visibility in dusty weather, drivers should control the speed to ensure safety; Airports, expressway and ferry terminals should take corresponding measures to ensure traffic safety.

It is particularly important to note that the meteorological conditions in Inner Mongolia fire area are not conducive to fire fighting. Experts from the Central Meteorological Observatory pointed out that this is mainly manifested as follows: First, strong winds easily lead to the spread of fire areas; Second, the wind direction may change in rotation, which poses a great threat to the safety of firefighters and equipment; Third, the low temperature at night is not conducive to the physical recovery of firefighters; Fourth, there will be less precipitation in the next four days, and the air around the fire will be dry. However, the forecast also shows that there is weak precipitation in the fire area on the night of the 5 th. Relevant personnel can seize the favorable opportunity to take artificial precipitation enhancement operations to control the fire.