关键词: 沙尘暴, 浮尘天气, 干冷空气, 稳定性

Abstract:

By using global reanalysis data from NCEP /NCAR, the durative of a floating dust overBeijing during 7 - 10 in Ap ril of 2006 was analyzed. Itwas found that the impact systems of the floating dustweatherwereWest Siberia cold eddy, Okhotsk warm high and Tibetan Plateau high ridge at the level of 500 hPa; the dry - cold air at the level of 700 hPa transferred to Beijing ceaselessly, and the cold advection and baroclinic instabilitywere strong, the gale and dust storm occurred in the strong cold advection area; the weak instability stratification in surface layer and mid - low level in the south ofNorth China resulted in weak ascending air flow, then transported dust particles to Beijing depending on the easterlywind in front of the surface low p- ressure. Because of the neutral or instability condition atmid - low level over Beijing, the dust particleswere difficult to go down, and the floating dustweather lasted for four days.

Key words: dust - storm, floating dustweather, dry cold air, stability