From May 4th to 5th, the most widespread and intense sand and dust weather this year hit 10 provinces (municipalities and autonomous regions) in northern my country, including Hebei. According to the Provincial Meteorological Observatory, this is the largest sand and dust weather event in Hebei in the past 10 years. So, why did this sandstorm have such a large impact? What factors caused this dust weather? Where does this dust come from and when does it leave? Yesterday, the reporter interviewed Guo Yingchun, chief meteorological service expert of the Hebei Meteorological Observatory.
Monitoring: 77 counties have strong winds with maximum level 10.
On May 4, floating dust or sand weather occurred in Zhangjiakou, Chengde, Langfang, Baoding, Shijiazhuang and other places. Mainly floating dust. Since yesterday morning, winds have increased in various places. Most areas have northwest winds of magnitude 4-6 and gusts of magnitude 7-8. Among them, 77 counties (cities and districts) have experienced strong winds with instantaneous wind speeds of more than 17 meters/second (7 Level 10 or above), the maximum instantaneous wind speed in Kangbao is 28 meters/second (Level 10), there is floating dust or sand in most areas of the province, and the minimum visibility in various places is below 5 kilometers.
Guo Yingchun said that the sand and dust weather that occurred from May 4 to yesterday was the largest sand and dust weather process that has occurred in Hebei in the past 10 years. “Compared with normal years this year, the sand and dust weather that occurred in early May Large-scale floating dust or blowing sand weather is late in the year. "Floating dust is a weather phenomenon caused by dust and other fine particles produced in distant places or nearby floating in the air. At this time, the wind speed is small, and on the 4th, floating dust is the main force; blowing sand. It is a weather phenomenon caused by local or nearby dust being blown up by the wind. At this time, the wind speed is relatively high, which was very typical yesterday. Floating dust and blowing sand will affect visibility (both between 1 and 10 kilometers), which will have a negative impact on traffic.
Cause: Strong winds blowing from the sand source in the north help transport sand and dust
The windy and dusty weather process in Hebei this time has the characteristics of strong gusts and wide impact. Guo Yingchun analyzed that in the past two days, Mongolia and Inner Mongolia have experienced frequent cold air activities and strong winds. This area is also the source of sandstorms. Recently, the temperature in the sand source areas has been higher, the precipitation has been lower, and the wind speed has been higher, which has provided opportunities for sand to rise. favorable conditions. The interaction of two unfavorable meteorological conditions, cold air and sand source areas, triggered this large-scale sand and dust weather.
Since the spring of this year, there have been two sand and dust weather events in Hebei Province (April 30 and May 4-5). The total number of sand and dust weather events has been higher than the same period in the past 10 years (3.3 times). Less, the same as the same period last year; in terms of sand and dust weather types, blowing sand was the main weather on April 30, and floating dust and blowing sand were the main weather on May 4 and 5 respectively. The main reason for the reduction of sand and dust weather is that on the one hand, the cold air is weakening due to climate warming; in addition, the construction of protective forests and the development of windbreak and sand fixation work have also played a good role. However, this time the dust was transported at an altitude of more than 5,000 meters. It is not surprising that the dust from Mongolia can be transported to Hebei.