关键词: 强沙尘暴, 起沙条件, 起沙机制, 稳定度

Abstract: Based on conventional meteorological observation data, FY4A satellite data, vegetation cover data and reanalysis data, the formation mechanism, transmission characteristics and influencing factors of a largescale severe dust storm occurring from March 14 to 18, 2021 in northern China were analyzed. The results are as follows: (1) Drought, high  temperature, less rainfall and low vegetation coverage in the earlier period in most parts of northern China provided a good sand source condition for occurrence of the strong sand dust storm weather. (2) The dust weather was caused by the strong development of Mongolia cyclone and the combined action of cold high pressure behind it. (3) The dust weather process was divided into two stages. At the first stage it was caused by the strong winds passing behind the ground cold front, which mainly occurred in North China and Northeast China. At the second stage it was caused by the southward diffusion of highaltitude dust that did not dissipate at the early stage and the backflow of east wind, which mainly occurred in Northwestern China. (4) The analysis of physical quantities such as horizontal helicity, the mixing layer height and vertical velocity showed that the dust emission conditions were insufficient in most areas of China, so the sand dust weather was mainly affected by the upstream sand dust transportation. For the eastern region of China, the contribution of dust storm was mainly from the southern part of Mongolia. While in Northwest China it was mainly contributed by Mongolia and its own dust.

Key words: Key words: strong dust storm, dust emission condition, dust emission mechanism, stability