关键词: 沙尘暴, 高空急流, 不稳定层结, 动量下传, 农业影响, 河西走廊

Abstract: According to the hourly observation data, MICAPS data, and NECP/NCAR global reanalysis data from the Liangzhou, Minqin and Yongchang observatory, Gansu province, the small-scale sandstorm weather process that occurred in the eastern part of the Hexi corridor on May 18, 2018 has been analyzed. The results showed that, the early climatic background such as drought, low rainfall and high temperature and the positive helicity before the sandstorm provided abundant dust for the sandstorm. The small trough at the bottom of the 500 hPa cold trough, the weak cold advection at 700 hPa and the northward cold front were the main reasons for the occurrence of the sandstorm. The rapid increase and decrease of the upper-level jet stream and the continuous maintenance of the 200 hPa jet stream caused the sandstorm to occur quickly and end rapidly, while the extremely dry and unstable stratification, as well as the huge temperature gradients at high and low altitudes promoted the transportation of momentum at high altitudes, and increased the wind power of horizontal direction, which induced the sandstorm and it caused certain harm to facility agriculture and adverse effects on the growth of crops.

Key words: sandstorm, upper-level jet stream, unstable stratification, momentum transportation, agricultural impact, Hexi corridor