Analysis of the dynamic mechanics of a dust event in Liaoning in 2004
2004年辽宁地区一次沙尘天气过程的动力机制分析

Based on NCEP (National Centers for Environmental Prediction), aerosol index and pollution data, the dynamic mechanics of a typical dust event over Liaoning Province during 14~16 April 2004 are analyzed based on climate and air circulation information. The analysis shows that climactic background of North China in 2004 promoted the dust event. Cold polar air traveled from north to south led by an upper atmosphere trough and the powerful Mongolian depression formed typical dust circulation patterns in north-east China. Considering the dust emission, upper and lower level jet streams formed a pumping effect because of divergence at the upper level, which strengthened the low-level updraft. The strong updraft resulting from coupling between the upper and lower level jet was the main mechanism behind this sand event yet the vertical distribution of helicity was also important, because the vertical structure made a powerful ascending area where the air converged on the upper level and diverged on the lower level. Thus conditions were very favorable to the development of sand storms.