2000年4月12日特强沙尘暴天气分析

An Analysis of Strong Sandstorm on 12th April

对 2 0 0 0年 4月 1 2日发生在甘肃、青海、宁夏的一次强沙尘暴天气进行了天气成因分析。分析指出 ,“4.1 2”沙尘暴是西北路径强冷空气引发的锋后西大风沙尘暴天气过程。前期持续增温为沙尘暴的发生提供了有利的热力条件 ;河西气旋性涡旋的生成、发展是激发沙尘暴的中尺度天气系统 ;西北地区干暖舌的形成和维持对沙尘暴的发生以及落区有很好的指示性。高空急流发生异变时的非平衡状态变化导致对流层中下部锋区加强和大气层结不稳定 ,为中小尺度系统和沙尘暴的产生提供了有利的大尺度环流背景。河西狭管地形和特殊的流沙、尾矿砂地表为沙尘暴形成提供了有利的地理环境。

A strong sandstorm weather process occurred on the 12th April 2000 in Gansu,Shanxi and Ningxia provinces is analyzed.The results show that the event was caused by the northwest strong cold air.Before the occurrence of sandstorm,continual temperature rising was the favorable thermal condition,and the development of Hexi cyclonic eddy was meso scale system which stimulated the sandstorm.The development and persistence of dry warmer sector in northwest is the index of its occurrence.Unbalanced state of the abnormal jet intensified the front over middle and lower troposphere and the unsteady atmospheric level which provided a favorable large scale circulation environment.Moreover,the long and narrow terrain and special quicksand,quick ore sand over the ground surface also provided a favorable condition geographically.