克州地区春季一次强风沙天气成因分析

An Analysis of a Strong Wind in Kezhou Area

利用常规观测资料、数值预报物理量场和NCEP/NCAR每日4次全球再分析网格点资料,对2010年3月28日发生在克州境内的一场罕见大风、沙尘暴天气过程进行了诊断分析,探讨了这次强风沙天气的成因。结果表明:高空低压槽和地面冷锋及锋后强冷平流、高空急流的加强及高空形成的次级环流使高空动量有效下传到地面起到了积极的动能作用,大风沙尘上空螺旋度上负下正的垂直分布与大风沙尘的出现有很好的对应关系,大风沙尘发生前后压、温、湿要素出现的剧烈突变对预报也有很好的指示意义。

Using the conventional observation data, numerical prediction physical quantity field and NCEP/NCAR reanalysis grid points data, this paper carried through diagnostic analysis on an infrequent weather process with gale and sandstorm happened in Kezhou of Xinjiang in March 28th 2010, and explored the reasons for the extreme weather. The results showed that： The combination of the upper low trough, surface cold front, strong cold advection after front, intensified upper-level jet and secondary circulation in upper-air made the upper momentum downward transfer efficiently to land surface. The vertical helicity distribution with the feature of positive upper-level and negative lower-level was well related to the gale and sandstorm weather. The intense variations of weather factors such as pressure, temperature, humidity before and after the extreme weather showed good instructive significance for forecasting.