The sandstorm that obscures the sky in the capital is lingering fear.

  According to statistics from the Central Meteorological Observatory, from the night of March 14th to the morning of March 16th, large-scale sand or floating dust occurred in the northwestern region, most of northern China, the central and western regions of Northeast China, Huanghuai, and northern Jianghuai. Southern Xinjiang, Inner Mongolia, Gansu Sandstorms or strong sandstorms occurred in parts of the west, central and northern Ningxia, northern Shaanxi, northwestern Shanxi, northern Hebei, and Beijing. The area of ​​sandstorms exceeded 3.8 million square kilometers.

  "This process has reached the intensity of a strong sandstorm, which is the strongest sandstorm weather process in my country in the past 10 years. The peak PM10 concentration in many parts of the north has exceeded 5000 micrograms/m3." said Zhang Bihui, director of the Environmental Meteorological Center of China Meteorological Administration.

  Frequent visitor of Sand Dust Spring

  Data show that from 2000 to 2020, there were 32 large-scale severe sandstorm weather processes in my country, with an average of about 1.5 times per year, mainly in March and April (11 times in March and 14 times in April), with the most occurrences in the year 5 times (2001, 2002, 2006).

The scope and intensity of this process are comparable to those of March 18-22, 2002 and March 19-22, 2010.

  Why does the sandy weather become a frequent visitor in spring?

China Weather Network analyst Shi Yan said that after March every year, sand and dust weather in northern my country has entered a period of high incidence.

The temperature rebounded rapidly in spring, the northern sand source area began to thaw, and with less precipitation, it was difficult to suppress the sand and dust, which provided material conditions for the occurrence of sand and dust.

At the same time, during this season, cold air activities in the north are still frequent, and windy weather is frequent, which easily blows up the soil or sand on the surface, resulting in dusty weather.

  "Generally speaking, spring is the season with high incidence of sand and dust, but if there is little precipitation and the surface is dry, sand and dust weather will still occur in winter or even autumn." Zhang Bihui emphasized that the sand and dust weather is the strong atmospheric circulation. It is produced by the combination of dry and bare surface characteristics of the sand source.

  The frequency of sand and dust is decreasing

  Monitoring by the National Climate Center of the China Meteorological Administration shows that since 1961, the average number of dust days and dust storm days in spring in northern my country has decreased significantly.

Especially in the past 20 years (2001-2020), the average number of dust days in spring was 3.4 days, 1.6 days less than the same period in normal years; and the number of dust storm days was 0.6 days, 0.5 days less than the same period in normal years.

Zhou Bing, chief of the climate service of the National Climate Center, analyzed that there are several reasons for the reduction of dust weather.

Objectively speaking, in the past 10 years, due to the combined effects of man-made governance and climatic factors, the local environment of the sand source has improved.

In terms of climatic factors, with the global warming, my country’s climate has also shown obvious changes. The number of days of windy weather in the northern region has been significantly reduced, which is also the main reason for the reduction of sand and dust weather.

  "However, although sand and dust weather has decreased, natural disasters such as sand and dust storms have the characteristics of multiple causes, complexity, potential, periodicity, and suddenness. As long as the generation conditions are met,'sand storms' will still appear. "Zhou Bing said.

  Experts said that the current round of sand and dust weather will gradually weaken and dissipate on the 17th. However, due to the significantly higher temperature in the sand source area in the early period, the sand layer became loose after the frozen soil layer was thawed. Under favorable conditions of atmospheric circulation, strong sand still exists this spring. The possibility of dusty weather processes occurring.

  ◎Fu Lili, our reporter


  (Technology Daily, Beijing, March 16th)