新疆一次秋季暴雪天气的诊断分析

利用常规气象资料和诊断分析的方法,对2003年9月28日发生在新疆乌鲁木齐等地一次暴雪天气过程进行了研究。结果表明:伊朗副热带高压的东西摆动、南北振荡引起的中亚地区大气环流的剧烈变化是暴雪天气产生的大尺度背景;高空西南急流诱发的强上升运动和对流层低层天气尺度系统之间强烈的相互作用是暴雪天气形成的动力因子;干冷空气的侵入有利于干层的形成和维持,干层的存在使水汽和不稳定能量得以累积,增加了降水过程的对流不稳定性,有利于强降水天气的发生、发展和加强。

Diagnostic Analysis on a Snowstorm Event Occurred of Xinjiang in Fall

Based on the conventional meteorological data combined with diagnostic analysis,a snowstorm event occurred in Urumqi of Xinjiang Province on 28 September 2003 is studied.The results show that:(1) Dramatic changes of the central-Asia atmospheric general circulations caused by the oscillations of Iran subtropical high in both the east-west and south-north directions make the large-scale background condition of the snowstorm.(2) The strong upward motion induced by the upper southwest jet and the strong interaction between the synoptic-scale systems in the lower troposphere are the important dynamical factors.(3) The dry cold air intrusion contributes to the formation and maintenance of the dry level,which makes the accumulation of water vapor and instable energy possible,enhances the convective instability during the development of the rain/snow process,are favoured for the formation,development and enhancement of the heavy rain/snow.