Abstract:

A typical strong sand-dust event in Northern China from March 27 to 28, 2021 was analyzed using conventional meteorological data, sounding station meteorological observation data, retrieval data of sand-dust from satellite cloud images and the NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) reanalysis data.The results show that the dry (the average precipitation is less than 10 mm, and the area with negative precipitation anomaly is more than 80%) and hot (the temperature is 6℃ higher than usual) weather are the climatic background factors for the dust weather.At the same time, under the influence of the Mongolian cyclone, the strong wind at medium-low altitude and on the ground, the strong vertical ascending motion is the dynamic conditions for the dust weather.Based on the atmospheric temperature lapse rate, uplift index, K index, convective effective potential energy index, I_Conve index from 700 hPa to 850 hPa, I_Conve index from 700 hPa to the ground, and PW index, it indicates that the atmospheric structure in the sand source area is unstable, which provides thermal conditions for the occurrence of dust weather.The 24-hour backward trajectory analysis shows that the dust near the surface of Inner Mongolia is uplifted to 1000 m and transported over a long distance to a low level of about 500 m at Shenyang.The dust at the height of 4000~5000 m is transported to the high level about 1000~1500 m at Shenyang.

Key words: Strong wind, Dynamic conditions, Thermal conditions, Backward trajectory model