螺旋度在一次夏季强沙尘暴中的分析应用

Application of Helicity in Analyzing a Strong Summer Dust-storm Event

在分析2005年7月16—17日甘肃省河西走廊区域性强沙尘暴发生的气候背景及环流特征的基础上,将Tudurf等1997年给出的相对地面螺旋度以及Davies Jonces等1990年给出的相对风暴螺旋度应用到对强沙尘暴的诊断分析当中。结果显示,利用温度平流与相对地面螺旋度之间的关系比较容易得出天气系统经过的区域螺旋度的值,但相对地面螺旋度的计算结果依赖于对天气系统的准确分析,尤其是水平温度梯度的判断;相对风暴螺旋度的强中心与发生沙尘暴的强中心有很好的对应关系。

Based on the analysis of the climatic background and weather situation from 16-17 of July in 2005, the paper applied the Relative Earth Helicity by Tudurf at 1977 and the Relative Storm Helicity by Davies Jonces at 1990 to diagnose a severe dust-storm in summer in Hexi Corridor. The results show that it was easy to compute the value of helicity where the weather system passed by using the relationship between temperature advection and Relative Earth Helicity, but the correct relative helicity values came from exactly analyzing and diagnosing on the weather system, especially on the horizontal temperature gradient. The relative storm helicity high value center was homologous to the severe dust-storm center.