[ad_1]
Original caption: China reissued yellow warning for sand and dust storms. Why is sand and dust coming so often this year?
China News Service, Beijing, March 27 (Reporter Chen Su) This weekend, a large-scale sandstorm occurred again in northern China, and seven provinces were hit by sandstorms. On the 27th, the Central Meteorological Observatory issued a yellow warning for sand and dust storms.
In the middle of this month, northern China just experienced the “strongest sandstorm of the last decade”, and PM10 in many places “exploded”. Among them, the PM10 concentration in many areas of Beijing exceeded 9000 micrograms / m3. Compared to the previous round of sand and dust storms, how is the impact of this round of sand and dust storms?
Zhang Tao, chief forecaster of the Central Meteorological Observatory, said in an interview with a reporter for the China News Agency that the cause of this round of sand and dust is similar to the previous round. The source of sand is mainly in Mongolia, mainly due to the cooperation of the Mongolian cyclone and the high cold pressure.When the sand rises, the dust rises into the air and then is transmitted. However, the intensity of the Mongolian cyclone and the high cold pressure of this round is weaker than the previous one, and the intensity of the gale is slightly weaker. “In general, compared to the severe sandstorm process on March 14-18, the intensity of this sandstorm process is slightly weaker. The sandstorm affects the location to the east and the area of the storm. strong sand is smaller. “
According to the forecast of the Central Meteorological Observatory, sand and dust will reach the North China Plain from midnight on the 27th to early morning on the 28th, and there will be obvious sand and dust weather in Beijing, Hebei, Shaanxi, Shanxi , Henan and others. places. Beijing launched a Class IV emergency response to meteorological disasters (sand dust) at noon on the 27th.
From a perennial perspective, March to May is the period of high occurrence of sand and dust. However, the strong dust climate of “yellow sand all over the sky” has not occurred in northern China for many years. Furthermore, according to statistics from the Department of Meteorology, there have been significantly more sand and dust weather processes affecting China since the beginning of this year than in the same period of normal years. Why does sand and dust weather occur frequently this year?
Ren Guoyu, chief expert of the National Climate Center and adjunct professor at China University of Geosciences (Wuhan), told reporters from the China News Agency that this year, the intensity of sand and dust weather is higher. than in previous years, mainly due to the sand and dust source areas in Mongolia and Northwest China. Spring rainfall is unusually low, with southern Mongolia and northwestern Inner Mongolia reduced by 100% compared to normal years. Due to the lack of rainfall, the temperature in spring is also relatively high and the climate is abnormally dry. In this context, added to the strong winds caused by extratropical cyclones in spring, it is easy to blow dry soil or dust produced by drought into the northwest airflow and carry it to North China and elsewhere.
Faced with the sandstorm “hitting the field” again, people can’t help but worry about whether the sandstorm will become the norm in the future. Has China entered a “proliferation period” of sandstorms?
Ren Guoyu said that generally speaking, northern sandstorms occur mainly in spring, and the situation in the next month is not optimistic. From the perspective of long-term trends, it is necessary to keep looking at whether China has entered a period of frequent occurrence of sand and dust and whether there will be frequent sand and dust storms in the future.
He said that according to observations, in the past 60 years, due to the influence of climate change, rainfall in the sand source area has continued to increase, and the wind speed has also decreased, making the frequency of the weather sand and dust continue to decline. be lower overall, and the downward trend in the last 20 years is also obvious. This year, precipitation in the sand source area was abnormally low, which is inconsistent with the long-term trend.
“The drought in the sand source from the beginning of this year to the present is mainly related to the strong winter monsoon and unusually strong cold air. It is mainly a year-on-year weather anomaly, that is, normal short-term volatility. Because the Sandstorm observation data series is still relatively short, it is difficult to see that this type of fluctuation has an obvious periodicity. ” Ren Guoyu said there will be sandstorms in the spring, but if the sand source area is not as dry as this year, the number of sandstorms that will affect North China will not be as large as this year.
In terms of temperature conditions, Ma Jun, director of the Center for Public Environmental Research, believes that as one of the causes of the sandy and dusty weather this spring, Mongolia and northwest China have warmed faster than usual, which which has caused the appearance of dry. and dust sources exposed above. Global temperature has increased in recent years, and the average temperature rise in high-latitude regions is greater than in low-latitude regions. “If this climatic trend occurs more frequently, it can also lead to an increase in the frequency of strong sand and dust weather conditions.”
Meteorological experts recalled that there will be sandstorms in some parts of the north, the public should prevent respiratory diseases, reduce departures and pay attention to the adverse effects of sandstorms on transportation.
Speaking of measures to deal with sand and dust weather, Ren Guoyu said that the frequent sand and dust weather in the spring is mainly a natural phenomenon, and it is impossible for people to stop sand and dust storms in any way. The main answer is to make long-term weather predictions and short-term weather forecasts, and take precautions in advance. In addition, the strengthening of afforestation and pasture planting, or the implementation of construction or ecological restoration projects, can alleviate the local wind phenomenon to some extent. (End up)
