影响中国北方特强沙尘暴的环流系统分型研究

A Study on Weather Types of Super Strong Dust Storms in North of China

使用中央气象台出版的历史天气图资料,对1957～2002年发生在我国北方的33次特强沙尘暴过程的环流系统进行了分析研究,重点分析研究了环流系统的热力和动力结构、活动特征及高低层系统的相互配置;在此基础上,以形成触发沙尘暴强风的主要地面环流系统为依据,通过分类归纳,将形成我国北方特强沙尘暴的环流系统,划分成纯强干冷锋型、蒙古气旋与干冷锋混合型、蒙古冷高压南部倒槽型和干飑线与冷锋混合型4种类型。研究结果指出纯强干冷锋型的冷锋具有典型的2型冷锋的垂直结构,冷锋后有强大的气压梯度,冷平流强烈,锋后为西北大风,沙尘暴带为西北东南方向。蒙古气旋与干冷锋混合型以蒙古气旋的强烈发展为主要特征,气旋强烈加深,在地面强风形成中起着重要作用,气旋暖区及冷锋后为西南大风或偏西大风,沙尘暴带自西向东延伸,与气旋中心移动路径关系密切,冷锋后降温较弱。蒙古冷高压南部倒槽型强沙尘暴是由蒙古冷高压与河西暖倒槽相互作用形成强盛东风触发的,沙尘暴区范围较小,但稳定少动,持续时间较长。干飑线与冷锋混合型强沙尘暴是由冷锋前干飑线或中尺度低压扰动和冷锋相伴影响造成的,它可以和第、类同时发生,第、类天气尺度环流形势是产生该类强沙尘暴的环流背景。文章给出了各类特强沙尘暴的天气学概念模型。

Based on the historical weather charts (1957-1996, 2001-2002) from the central meteorological observatory,the analysis on the weather types of super strong dust storms was conducted. The super strong dust storm processes occurred 33 times in the north of China. The study focused on the thermal and dynamical factors, acting characteristic, and the collocation of weather systems between higher and lower troposphere. Then, according to the surface weather systems, the weather types of super strong dust storm were divided into four types: Dry Cold Front, Mongolia Cyclonic Cold Front, High Bottom-Inverse Trough and Cold Front-Dry Squall Line. The Dry Cold Front has a typical structure of II cold front type. It has characteristics of strong pressure grades, strong cold advection and the dust storm spread from West-North to South-East. The Mongolia Cyclonic Cold Front process the intensive development of cyclone produced the strong surface wind and the DS spread from west to east. The High Bottom-Inverse Trough DS process is induced by the strong east wind, which came from the interaction of the Mongolia cold high and the warm inverse trough at the western Yellow River. The DS its induced has a small scale and less moved and maintained for a long time. The Cold Front-Dry Squall Line DS process is caused by the coherent effect of the cold front and the prefrontal dry squall line (or the mesoscale low). It could happen with 1 or 2 DS type process. Their synoptic model was also provided.