内蒙古中西部地区一次强沙尘暴的垂直螺旋度诊断分析

利用常规观测资料和2.5°×2.5°NCEP资料对2010年3月19日发生在内蒙古中西部地区的一次强沙尘暴天气的垂直螺旋度进行了诊断分析。结果表明,沙尘暴发生期间,螺旋度分布呈现出明显的＂上负下正＂分层结构,这种分层结构出现的时间与强沙尘暴出现的时间基本一致,且随着正螺旋度区域范围扩大、高度抬高,沙尘暴发展愈强烈;高层螺旋度负值的演变与沙尘暴的出现有一定的对应关系,该诊断分析对于沙尘暴预报有一定指示意义。

Diagnostic Analysis of Vertical Helicity of A Severe Sandstorm in Midwestern region of Inner Mongolia

Based on the conventional observation data from automatic weather station and NCEP reanalysis data, the vertical helicity of a severe sandstorm occurred on Mar 19th in 2010 over the middle west region of Inner Mongolia was diagnostically analyzed. The results showed that during the sandstorm the helieity, an obvious ＂negative above positive below＂ structure was observed, and this structure appeared at the same time as strong sandstorm occurred. Following the range extension and height elevated of positive helicity, the sandstorm gradually became stronger. The corresponding relation between the evolution of negative helicity at high level and appearance of the sandstorm was also observed in this study. Diagnostic analysis might be helpful for the dust storms forecast.