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 has just experienced "the strongest sand and dust storm in the past decade", and PM10 in many places "exploded". Among them, the concentration of PM10 in many areas of Beijing exceeded 9,000 micrograms/m3.
Compared with the previous round of sand and dust weather, 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 from China News Agency that the cause of this round of sand and dust is similar to the previous round. The source of the sand is mainly in Mongolia, mainly due to the cooperation of Mongolian cyclone and cold high pressure. When the sand is lifted up, the dust rises into the air and then transmits.
However, the intensity of the Mongolian cyclone and cold high pressure in this round is weaker than the previous one, and the extremeness of the gale is slightly weaker.
"On the whole, compared with the strong sandstorm weather process from March 14th to 18th, the intensity of this sandstorm weather process is slightly weaker, the sandstorm affects the location to the east, and the strong sandstorm range is smaller."
According to the Central Meteorological Observatory's forecast, sand and dust will reach the North China Plain from midnight on the 27th to the early morning of the 28th, and obvious sand and dust weather will occur in Beijing, Hebei, Shaanxi, Shanxi, Henan and other 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 "yellow sand all over the sky" strong dust weather has not occurred in northern China for many years.
In addition, according to statistics from the Meteorological Department, 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 do sand and dust weather occur frequently this year?
Ren Guoyu, chief expert of the National Climate Center and part-time professor of China University of Geosciences (Wuhan), told reporters that the intensity of sand and dust weather this year is higher than in previous years, mainly because of the sand and dust source areas in Mongolia and northwest China. The spring rainfall is unusually low, and southern Mongolia and northwest Inner Mongolia are reduced by 100% compared to normal years. Due to the lack of precipitation, the temperature in spring is also relatively high and the climate is abnormally dry.
In this context, coupled with the strong winds caused by extratropical cyclones in spring, it is easy to lift dry soil or dust generated by drought into the northwestern airflow and bring it to North China and other places.
Faced with the “return” of the sandstorm, people cannot 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 mainly occur in spring, and the situation in the next month or so is not optimistic.
From the perspective of long-term trends, whether China has entered a period of frequent dust and dust, and whether dust storms will occur frequently in spring in the future, still needs further observation.
He said that according to observations, in the past 60 years, due to the influence of climate change, precipitation in the sand source area has continued to increase, and wind speed has also been decreasing, making the frequency of sand and dust weather continue to be lower overall, and the decreasing trend in the last 20 years is also obvious.
This year, the 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 the unusually strong cold air. It is mainly an interannual climate anomaly, that is, a normal short-term volatility. Because the sandstorm observation data series are still relatively short, it is difficult to It can be seen that this kind of fluctuation has obvious periodicity." Ren Guoyu said that there will be dust storms in the spring, but if the sand source area is not as dry as this year, the number of dust storms affecting North China will not be as many as this year.
From the perspective of temperature conditions, Ma Jun, director of the Public Environmental Research Center, believes that as one of the causes of the sand and dust weather this spring, Mongolia and northwestern China have warmed up faster than usual, leading to the emergence of dry and exposed dust sources earlier.
The global temperature has been rising in recent years, and the average temperature rise in high-latitude regions is greater than that in low-latitude regions.
"If this climate trend occurs more frequently, it may also lead to an increase in the frequency of strong sand and dust weather."
Meteorological experts reminded that there will be sandstorms in some parts of the north. The public needs to prevent respiratory diseases, reduce going out, 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 spring is mainly a natural phenomenon, and it is impossible for people to stop sand and dust storms by any means.
The main response is to make long-term climate predictions and short-term weather forecasts, and take precautions in advance.
In addition, strengthening afforestation and grass planting, or implementing ecological construction or restoration projects, may alleviate the phenomenon of local sand blowing to a certain extent.
(Finish)